Following the seismic microzonation of Basel, the project «Basel Erdbebenvorsorge» was funded by the canton Basel-Stadt. It aimed first at improving the seismic network in Basel and collecting data for the next generation of microzonation studies, and second at proposing earthquake scenarios and risk computations for all cantonal school buildings. This study sets the framework for studies including the whole city, supporting earthquake mitigation and crisis management.

In a first phase, 6 new modern strong-motion stations have been installed, complementing the installations from the SSMNet renewal project. The sites have been characterized through geophysical measurements. In addition, 5 temporary stations have been installed for the period of the project. In a second phase, a new amplification map was developed accounting for all information collected for the completed microzonation study and more recent data. The third phase was the development of a risk framework using the Openquake software. The company Resonance Ingénieurs-Conseils performed the assessment of the capacity curves of the school buildings, that were implemented through fragility curves. A particular focus of the project was put on the uncertainties of the risk-calculation process. Scenarios for typical events of the area were assessed, based on the historical seismicity and the de-aggregation of the regional seismic hazard. The effect of retrofitting of the school-building stock through the ongoing HARMOS project was quantified with a cost-benefit analysis.

The objective of this project is the microzonation of the Bucharest city (Romania).

For a better understanding of the geological structure under Bucharest, non-invasive methods are used, as: wavelet-polarization analysis at each station, H/V for ambient vibrations and earthquakes, and the three-components array analysis of ambient vibration recordings from URS experiment, in order to retrieve the characteristics of surface waves. Surface wave dispersion curves, their ellipticity and the data from boreholes (depth < 100m) are jointly inverted to estimate the velocity structure under the city.

The final 3D structure will be used for the numerical simulation of the seismic waves propagation from the Vrancea intermediate-depth source to the city in order to investigate the seismic hazard in the city.

Data used in this project are from: National Institute of Earth Physics, CRC461-Proiect URS – URban Seismology 2003-2004, BIGSEES ”BrIdging the Gap between Seismology and Earthquake Engineering: from the Seismicity of Romania towards a refined implementation of seismic action EN1998-1 in earthquake resistant design of buildings”

NERA was a project in the Seventh Framework Program (FP7) of the European Commission (EC) that integrated key research infrastructures in Europe to monitor earthquakes and assess their hazard and risk to improve and make a long-term impact on the assessment and the reduction of the vulnerability of constructions and citizens to earthquakes.

Our group was involved in the Work package JRA1, Waveform modelling and site coefficients for basin response and topography, and Workpackage NA5, Networking near-fault observatories.

The key objective of JRA1 was to establish some scientifically solid and practically acceptable propositions to incorporate basin and surface topography effects in seismic design (building codes, microzonation studies, critical facilities). We contributed with a systematic study of the topographic site effects with emphasis on reasonable characterization of the both topographic site structures and observed effects on ground motion. We gathered available earthquake and ambient vibration recordings from sites with pronounced topography (Europe, Japan) and performed joint analysis with digital elevation models.

The results and final recommendations have been published in a report. These conclusions contribute to the ongoing (light) revision of EC8.

The objective of NA5 was to collaborate in sharing of technological and scientific experience and know-how between the near-fault observatories. We shared our experience with the installation (including data gathering and data archiving) of various instruments in the Valais region. This workpackage represented an infrastructural support for workpackage 2 of the project REAKT.

COGEAR was an interdisciplinary natural hazards project investigating the hazard chain induced by earthquakes. It addressed tectonic processes and the related variability of seismicity in space and time, earthquake forecasting and short-term precursors, and strong ground motion as a result of source and complex path effects.

We studied non-linear wave propagation phenomena, liquefaction and triggering of landslides in soils and rocks, as well as earthquake-induced snow avalanches. The Valais, and in particular parts of the Rhone, Visper and Matter valleys have been selected as study areas. Tasks included detailed field investigations, development and application of numerical modelling techniques, assessment of the susceptibility to seismically induced effects and installation of different monitoring systems to test and validate our models. These systems are for long-term operation and include a continuous GPS and seismic networks, a test installation for observing earthquake precursors, and a system to study site-effects and non-linear phenomena in two test areas (Visp, St. Niklaus-Randa). Risk-related aspects of impacts on buildings and lifelines were also considered.

COGEAR was supported by the Competence Center for Environment and Sustainability (CCES) of ETH Zurich.

For the city of Basel, a qualitative microzonation was performed in 1997. The zonation was mainly based mainly on the properties of the quaternary sediments. This triggered a study that provided a quantitative assessment of ground motion amplification in order to determine which levels of amplifications have to be taken into account a site-specific hazard assessment in the Basel area. It is the result of two large projects, the ETH project “Earthquake scenarios for Switzerland” (1997-2002) and the INTERREG project “Seismic Microzonation in the upper Rhine Graben area” (2003-2006) (Fäh end Huggenberger, 2006). Earthquakes in the Basel region triggered the strong motion network in Basel and provided a data set for comparison. Spectral ratios from recordings confirm the results of the microzonation study. Finally uniform hazard spectra were derived for each zone by combining the hazard on rock with the amplification functions. The microzonation is published on the Internet:

Basel Landschaft: http://geoview.bl.ch

Basel Stadt: www.geo.bs.ch/erdbebenmikrozonierung

I terremoti sono una seria minaccia per la Svizzera. La stima della pericolosità sismica è il primo passo per valutare e limitare il rischio sismico. Per la determinazione della pericolosità sismica utilizziamo informazioni regionali dei terremoti storici, della tettonica e della geologia, delle descrizioni storiche dei danni e modelli di propagazione delle onde sismiche.

In queste pagine presentiamo i risultati probabilistici di pericolosità sismica in Svizzera 2004. Questa analisi va a sostituire le mappe della pericolosità sismica del 1976, che si basavano su stime di intensità.

Tsunamis do not only happen in oceans, but they do also occur in lakes. This project aims to understand the trigger mechanisms, preconditions, processes and impacts of lake tsunamis within an interdisciplinary environment (limnogeologists, seismologists, geotechnical specialists, hydraulic engineers and hazard specialists). Two Work Packages of this project (WPresponse and WPhazard/ Tsunami-CH) are conducted at SED.

WPresponse aims to characterize the sediment-mechanical characteristics,to estimate the volumes of the sediments in Lake Lucerne, and to study the stability of the sediments under seismic shaking. For this purpose, ocean bottom seismometers (OBS) are placed in Lake Lucerne at selected locations (see map). These OBS are recording the seismic signal on short (days) and long (months) intervals. Cone Penetration Test (CPT) measurements are used to define the geotechnical characteristics of the sediment. This WP is financed by SNSF and ETH.

WPhazard aims to assess the tsunami hazard in Switzerland. Even though historical reports and studies of lake sediments in Switzerland are documenting numerous tsunamis, the basics and methods for assessing this danger - and the resulting risk on land - are still lacking. Also the typical warning times, the possibilities and limits of alarming are currently only insufficiently known. This work package, financed by the FOEN, is intended to comprehensively characterize for the first time the danger of tsunamis in Swiss lakes such as Lake Lucerne, Lake Brienz, and others and thus contribute to a sustainable and practice-oriented risk management.

The study of small earthquakes related to glacier flow, so-called icequakes, can reveal important insights into the dynamics and hydraulics of glaciers. Icequakes near the glacier bed are particularly interesting, because they may be a manifestation of microseismic stick-slip sliding. This phenomenon is not fully understood and has yet to be captured in ice flow models. At the same time, basal seismicity can be a manifestation of hydraulic fracturing as melt water opens up new water channels within and beneath the glacier, a process, which is analogous to the hydraulic stimulation within geothermal reservoirs.

This project focuses on the occurrence of sliding-related stick-slip icequakes beneath Aletschgletscher. Whereas these events have been confirmed beneath the polar ice sheets (e.g. Smith et al., 2015; Roeoesli et al., 2016), it is to date not clear if they also exist beneath relatively flat Alpine glaciers. To this end, the SED conducted a two-step seismometer deployment on the glacier tongue. In a first step, three shallow borehole seismometers were installed and maintained for 1.5 years (January 2015-July 2016). These data identified an icequake cluster at the glacier bed, which was monitored in near-real time with the help of state-of-the-art real-time data communication. In June 2016, an additional network with six seismometers was installed above the cluster to confirm that the recorded icequakes are indeed stick-slip events and to provide better hypocenter locations.

The seismic Aletschgletscher record is unique in that it contains stick-slip icequakes recorded at an unrivaled quality over more than a year. This will provide an unprecedented look at seismogenic stick-slip sliding and its changes over the course of a full year. As a result of harsh weather conditions in high-melt areas, on-ice seismometer installations are extremely difficult on Alpine glaciers. Consequently, the Aletschgletscher data set offers a first-of-its-kind view on how stick-slip seismicity changes as the glacier reacts to climatic changes.

Our project is embedded in cross-disciplinary collaborative research between the Glaciology division at the Laboratory of Hydraulics, Hydrology, and Glaciology (VAW) at ETH Zurich and the Exploration and Environmental Geophysics group at the Institute of Geophysics at ETH Zurich. In the past, these groups have collected milestone records in the field of glacier seismology (Podolskiy and Walter, 2016). The joint interpretation of the Aletschgletscher data will help to improve our understanding of glacier flow and its reaction to climate change and glacier retreat, also affecting the Swiss Alps.

The SED participated in building a state-of-the art seismic network in the Arctic. We built and now continue to operate 3 stations in the new international broadband seismic capability for Greenland, the GreenLand Ice Sheet monitoring Network (GLISN). This real-time sensor array enhances and upgrades performance of the very limited pre-existing Greenland seismic infrastructure for detecting and characterizing glacial earthquakes and other phenomena emitting seismic waves. The Greenland Ice Sheet is changing, and seismology has the means to “hear” and measure these changes. Continuous, long-term monitoring of the dynamics of the Greenland Ice Sheet and its relationship to global climate change is a fundamental observational enterprise which requires multi-sensing techniques. The development of GLISN brings the seismology component into focus for monitoring Greenland’s Ice Sheet.

Glacial earthquakes have been observed along the edges of Greenland with strong seasonality and increasing frequency since 2002 by continuously monitoring data from the Global Seismographic Network (GSN). These glacial earthquakes in the magnitude range 4.6-5.1 may be modeled as a large glacial ice mass sliding downhill several meters (e.g. 10 km3 by 10 m) on its basal surface over a duration of 30 to 60 seconds. Although the mechanics of sudden sliding motions at the glacial base are not known, seasonal and temporal patterns are consistent with a dynamic response to climate warming driven by an increase in surface melting and supply of meltwater to the glacial base, and suggest that the glacial earthquakes may serve as a marker of ice-sheet response to external forcing.

Before GLISN, the detection and characterization of smaller glacial earthquakes was limited by the propagation distance to globally distributed seismic stations. Now, glacial earthquakes can be identified only using the more than 30 GLISN seismic stations within and surrounding Greenland. Because of the long durations of sliding, these glacial earthquakes do not appear in standard earthquake catalogs, and are best detected by broadband seismometers, which accurately measure both fast (< second) and slow (> 100sec) vibrations. Such seismic monitoring of the Greenland Ice Sheet via glacial earthquakes will complement both surficial GPS monitoring and remote sensing from satellites, by providing sensitivity to the dynamics of the glaciers at basal depths. In addition, real-time detection of glacial earthquakes permits rapid response and focusing of other sensing techniques to the dynamic region of the Ice Sheet.

All the data from the GLISN is openly available to anyone in real-time, without restriction.

Chile has been struck by a number of very large earthquakes (magnitude 7.5 or greater) and tsunamis in the past. There is a clear need for building a system to provide rapid situational awareness, as well as earthquake and tsunami early warning. Since scientific instruments are expensive, we are exploring the use of dense networks of seismic and geodetic low-cost sensors. The Earthquake Science Center oft he U.S. Geological Survey (USGS) has recently started to deploy a prototype network of dedicated smartphone units along the Chilean coast (Brooks et al., 2016). Each sensor box contains a smartphone with integrated MEMS accelerometer, and an external consumer-quality GPS chip and antenna to determine real-time positioning data. The total cost of each box is on the order of a few hundred dollars, nearly two orders of magnitude lower than scientific-grade installations. A first subset of 9 smartphone-boxes has been installed in November 2015; another set of 200 units will be deployed by the end of 2016.

We will invert seismic and geodetic real-time data from the smartphone units to obtain finite-fault models of large earthquakes by joint application of the seismic FinDer algorithm developed at the Swiss Seismological Service (SED) (Böse et al., 2012, 2015) and the geodetic BEFORES algorithm developed by Minson et al. (2014).

The SED collaborates in this project closely with partners at the USGS, the University of Chile, Chilean National Seismological Center, University of Houston, and GISMatters Inc.

The objective of the ShakeAlert project is to implement a prototype Earthquake Early Warning (EEW) system for California and the pacific northwest of the United States. The system is currently sending warnings of imminent strong ground shaking to a selected group of test users. The project comprises algorithm development, EEW system design and implementation, and public outreach. The SED was involved in Phase I – III of the project, implementing and testing the Virtual Seismologist (VS) [Cua and Heaton, 2009], a Bayesian approach to EEW. In Phase III, the SED team also began to contribute to the development and implementation of FinDer, the first finite fault algorithm to be included in the prototype system. Currently about 300 scientists and engineers and several project partners from the public and private sector receive alerts from the ShakeAlert EEW system. The ShakeAlert project continues without formal ETH participation, though VS and FinDer continue to be core components in the development system.

The general objective of this EC-FP7 funded joint project was to improve the efficiency of real time earthquake risk mitigation methods and its capability of protecting structures, infrastructures and people. REAKT aimed at establishing the best practice on how to use jointly all the information coming from earthquake forecast, early warning and real time vulnerability assessment. All this information needs to be combined in a fully probabilistic framework, including realistic uncertainties estimations, to be used for decision making in real time.

REAKT used a system-level earthquake science approach that required that the various temporal scales of relevance for hazard and risk mitigation in the various WPs are integrated through common tools, databases and methods. 

Our group was involved in the Work Package 2: Physics of short term seismic changes and its use for large earthquakes predictability. The key objective was to improve short-term forecasting of large earthquakes through the monitoring of the seismic and strain activity within specific fault systems. We contributed with the monitoring system, which has been installed in the Valais region including dense seismic network, GPS, geochemical and geomagnetic sensors. Special attention was paid to the analysis of seismic swarms.

AlpArray is a European initiative to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps-Apennines-Carpathians-Dinarides orogenic system. The initiative integrates present-day Earth observables with high-resolution geophysical imaging of 3D structure and physical properties of the lithosphere and of the upper mantle, with focus on a high-end seismological array.

AlpArray is a major scientific collaboration with over 40 participant institutions. One of the main actions of the AlpArray initiative is to collect top-quality seismological data from a dense network of temporary broadband seismic stations. This complements the existing permanent broadband stations to ensure homogeneous coverage of the Alpine area, with station spacing on the order of 30km. 24 institutions are currently involved in the AlpArray Seismic Network (AASN), which will eventually install over 250 temporary stations in 12 countries. The AASN officially started on 1 January 2016 and will operate for at least 2 years. A complimentary ocean bottom seismometer (OBS) component is expected in 2017.

The Swiss contribution to the AASN is completed, with 23 temporary stations installed in Switzerland, Italy, Bosnia and Herzogovina, Croatia and Hungary. All national broadband stations also contribute to the AASN.

The Seismology and Geodynamics group (SEG) and the Swiss Seismological Service (SED) at the ETH in Zurich take leading roles in the project. Prof Edi Kissling is the project coordinator. Irene Molinari (SEG), John Clinton (SED) and Gyorgy Hetenyi (former SED, now at the University of Lausanne) lead AlpArray working groups, Irene Molinari also manages the Swiss component of the AASN.

More information is available on the project website.

Um in Zukunft die Gefahren von natürlichen und induzierten Erdbeben besser abschätzen zu können, braucht es ein genaueres Verständnis von Verwerfungszonen in tektonisch aktiven Gebieten wie der Schweiz. Mit Hilfe geophysikalischer Abbildungsverfahren und geologischen Kartierungen wurden in den letzten Jahren zahlreiche Verwerfungen in den schweizerischen Alpen und im nördlichen Alpenvorland identifiziert. Allerdings treten in vielen Fällen Erdbeben abseits dieser kartierten Verwerfungen auf, was die Frage nach den tektonischen Prozessen und Mechanismen aufwirft, die diesen Erdbeben zugrunde liegen.  

Ziel dieses Projektes ist es, durch verbesserte geophysikalische Inversionsverfahren die Strukturen von Verwerfungszonen hochauflösend abzubilden und daraus Erkenntnisse über mechanische Eigenschaften der Bruchsysteme abzuleiten. Dazu werden unter anderem Verfahren der seismischen Tomografie mit hochauflösender Erdbebenlokalisierung kombiniert. Die Anwendung konzentriert sich auf zwei Regionen in der Schweiz: (i) einer äußerst aktiven Erdbebenzone nördlich des Rhônetals im Kanton Wallis, (ii) einer Verwerfungszone nahe St. Gallen, die während Stimulationsmaßnahmen für ein geplantes Geothermiekraftwerk aktiviert wurde.

Durch die Anwendung verbesserter Abbildungsverfahren erwarten wir zum einen neue Erkenntnisse über den Zusammenhang zwischen existierenden Verwerfungen und dem Auftreten von Erdbeben. Zudem sind die beiden Untersuchungsgebiete von hoher gesellschaftlicher Relevanz. Das Wallis ist die Region mit der größten seismischen Gefährdung der Schweiz und ein Großteil der gegenwärtigen Seismizität in diesem Gebiet steht in Verbindung mit der Erdbebenzone nördlich des Rhônetals. Die St. Gallen Verwerfungszone bietet Gelegenheit zur Untersuchung der Erdbebengefährdung im dicht besiedelten Molasse Becken, welches potentieller Standort zukünftiger Geothermieprojekte und atomarer Endlager ist.

The Eastern, "straight" part of the Alps is home to a number of open questions. The most widespreadly known question is about lithospheric slab hanging beneath the Eastern Alps. Is it Adriatic (Lippitsch et al. 2003)? Is it European (Mitterbauer et al. 2011)? What is its extent and the related velocity anomaly?

Beyond carrying out tomographic calculations, one can also characterize the fabric of the lower crust with receiver functions. In the India-Asia collision zone this has helped to point out that the main lithosphere boundary is located at a very different place than the surface boundary of deformation. Anisotropic receiver function calculations are therefore one of the first tools to be applied on EASI data, with the main question of determining the role of the lower crust in shaping the orogen.

A recent Moho map compilation reveals another interesting features beneath the Eastern Alps and between the Europe and Adria plates: a Moho "gap" or "hole" (Spada et al. 2013). Near 47°N latitude and between 12° and 15.5°E longitude the crust-mantle boundary is not defined, or at least it does not appear as a sharp discontinuity. Mapping the extent of this hole, and characterizing the velocity gradient from crustal to mantle conditions is an interesting goal to tackle.

The relationship of the Alpine orogen to the adjacent foreland basin and the lithospheric blocks of the Bohemian Massif, with their own characteristic seismic signatures, is a structural target of EASI.

Our research methods include tomography, ambient noise analysis and receiver functions, with anisotropy included in all three types of investigations. The depth range of investigations encompasses the crust and the mantle lithosphere, down to the LAB.

Bhutan, a kingdom in the Eastern Himalayas, is living in self-imposed isolation: in order to preserve local culture, traditions and the environment, foreigners can enter in groups and in limited number only. Consequently, our geoscientific knowledge is very limited compared to other parts of the orogen. The first geological map was compiled in 1983 by the famous Swiss geologist Augusto Gansser. From a geophysical perspective, Bhutan is almost a blank spot: only very limited information exists on seismicity which shows a lower level of earthquake activity compared to other parts of the Himalayas; there is knowledge neither of the structure nor of the physical properties of the crust and the lithosphere. Illuminating the deep structure of Bhutan and comparing it with the much better known Central Himalayas of Nepal is highly relevant both for evaluating the earthquake hazard and for improving our geodynamic picture of the orogen.

We conducted a temporary seismic experiment in Bhutan. Two densely spaced profiles across the orogen allow us to produce the first images of the structure of the lithosphere in the Eastern Himalayas, as well as give an insight into lateral variations along the mountain belt. Our network provides reliable information on seismicity in Bhutan and establishes the first seismic velocity model of the crust. Furthermore, we will apply ambient noise tomography to map the physical properties of the lithosphere. The results will be interpreted jointly with gravity data to build physical models of the Eastern Himalayas as well as to draw conclusions on its geodynamics. Especially, seismotectonic studies that we plan to conduct by comparing different segments of the Himalayas may shed light on the origin of the apparent seismic gap in Bhutan.

Augusto Gansser, "Geology Father of the Himalayas" and first geological mapmaker of Bhutan, has passed away earlier this year (2012), at the age of 101. We would like to dedicate this experiment to his memory.

Outreach

• Article on the project results in Kuensel, Bhutan's most read newspaper: part I, part II (2015.05.09. and 16.)
• Interview in ETH Life [en] [de] (2013.02.12.)
• Article in the Newsletter of the Society Switzerland-Bhutan (2013.06.)

DESTRESS is a Horizon 2020 supported programme aiming to demonstrate methods of EGS (enhanced geothermal systems) and thereby expanding knowledge and providing solutions for a more economical, sustainable and environmentally responsible exploitation of underground heat. EGS allow a widespread use of the enormous untapped geothermal energy potential. DESTRESS improves the understanding of technological, business and societal opportunities and risks related to geothermal energy.

The concepts explored are based on experiences in previous projects (e.g. GEISER), on scientific progress and developments in other fields, mainly the oil and gas sector. Recently developed stimulation methods are adapted to geothermal needs, applied to new geothermal sites and prepared for the market uptake. The main focus lays on stimulation treatments with minimized environmental hazard, which address site-specific geological requirements. The overall objective is to develop best practices in creating a reservoir with increased transmissivity, sustainable productivity and a minimized level of induced seismicity. Existing and new project’s test sites, pilot and demonstration facilities were chosen to demonstrate the DESTRESS concept.

DESTRESS assembles an international consortium involving major knowledge institutes and key industry from Europe and South Korea to guarantee the increase in EGS-technology performance and accelerated market penetration.

RT-RAMSIS is a joint CTI project between the Swiss Seismological Service SED and GeoEnergie Suisse AG. It builds on research results from previous joint research projects GEOSIM and GEOBEST. We are developing and validating a near real time hazard and risk assessment framework for induced seismicity in geothermal projects. With fluid injection rates and micro-earthquakes recorded in near real-time and prepared as input, the framework uses statistical and hybrid statistical-hydromechanical ensemble models to forecast seismicity in six hour intervals. Subsequent stages then compute probabilistic seismic hazard and risk estimates based on different injection scenarios and thereby help the operator to balance risk and reservoir stimulation efficiency.

Core research activities in this project are in the development of fast, reliable and precise micro-earthquake detection algorithms, in the assessment and weighting of forecast model performance and in the enhancement and validation of statistical and mechanical seismic forecast models.

In the last few years, major and damaging earthquakes were felt in regions supposedly affected by a low rate of natural seismicity. Such events have become an extremely important topic of discussion in both Europe and North America, since several major events were associated to industrial activities. The main focus of this proposed research is the study of induced seismicity during exploitation of natural underground resources. More specifically, this proposal focuses on one side on a detailed understanding of the deep fault and/or fractures reactivation associated with the fluid injection. On the other side, the proposed research plans to investigate the mitigation of large magnitude induced seismicity, which may pose at risk the affected population and structures, as well as acting as obstacle to the development of new techniques for the exploitation of deep underground resources. First the project aims to understand the physics associated with the induced seismicity caused by anthropogenic activities. Secondly, the project aims to investigate in which conditions fluid-induced seismicity can be used as a tool. For example, the shearing process of fault and fracture, or the creation of new fractures, are needed to increase the permeability, and hence to enhance the fluid circulation at depth, eventually resulting in a more efficient energy production. However, such processes may, at the same time, produce seismicity that can be felt by local population.

• How is the induced seismicity affecting the growth of a geothermal reservoir? When does it act as a potential seal breaching during storage operation?
• Is it possible to use induced seismicity to develop a high permeability system, while constraining the earthquakes maximum magnitude? Or can a gas be stored in a safe (no seismic) way?

Understanding the fundamental processes will help in finding new methods to safely extract energy, whose request nowadays is constantly increasing.

The project will address the above open questions by theoretical studies, laboratory, and applied fieldwork. I plan to use data collected from on-going experiments (laboratory and in-situ) to improve numerical models. Numerical tools to be used include: thermo-hydromechanical modeling (THM), discrete fracture network (DFN), and statistical, as well as hybrid simulators.

The first phase of this project involves the participation in the In-situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site. Goal of the experiment series is the permeability enhancement of a decameter rock volume intersected with two fault zones. The permeability enhancement process is accompanied by slip along the faults, which is achieved by high-pressure fluid injection (i.e. hydraulic shearing). Fluid injection is performed in several borehole sections distributed over two injection boreholes drilled trough the target fault zones. During the experiment hydraulic processes, mechanical processes and induced micro-seismicity are monitored with an unprecedented multi-sensor monitoring system leading to a unique and high quality dataset.
The goal of the second phase of the project is the detailed processing of recorded micro-seismic data. The objective is to determine a wide range of earthquake source parameters. The adaptation and further development of seismological processing techniques to the decameter scale make this task particularly delicate.

The third phase of the project will bring together micro-seismic data and other measured data during the experiment and shed light into the physical understanding of induced earthquakes.

Finally, forecasting skills of models for induced seismicity are tested on the Grimsel high quality dataset.

Nel quadro del progetto di ricerca GeoBest, dalla primavera del 2012 il Servizio Sismico Svizzero (SED) con sede all’ETH di Zurigo si occupa del monitoraggio sismico del progetto di geotermia della città di San Gallo. A tal fine, in collaborazione con la Sankt Galler Stadtwerke, l’azienda elettrica di San Gallo, il SED ha installato sei nuove stazioni sismiche nella regione di San Gallo. L’obiettivo del monitoraggio è rilevare possibili piccoli terremoti – i cosiddetti microterremoti – nelle vicinanze dei siti dove si svolgono i lavori di trivellazione, per chiarire se questi vengono causati dal progetto di geotermia o se hanno un’origine naturale. Inoltre, il progetto permette non solo di raccogliere importanti dati di base per comprendere meglio la geotermia di profondità, ma di utilizzarli come indispensabile patrimonio di esperienze per garantire alle autorità cantonali e alle imprese di gestione la sicurezza pianificatoria in vista dei futuri progetti di geotermia.

Dopo l’interruzione del progetto di geotermia nella primavera del 2014, il SED svolgerà l’attività di monitoraggio in forma ridotta sino almeno al settembre 2020. La Sankt Galler Stadtwerke supporta il monitoraggio nel quadro del progetto UE "Science for Clean Energy (S4CE)".

GEOTHERM-2 conducts cross-disciplinary research towards the development of Enhanced Geothermal Systems (EGS). EGS is a technology that will allow the heat resources residing at several kilometers depths to be exploited for electricity and heat production. At present, EGS technology is not mature; two of the key challenges are the difficulty of (1) engineering a lasting heat exchanger with appropriate properties within deep, hot, low-porosity rocks, and (2) the risk of inducing felt and potentially hazardous seismic events during the development and operation of the heat exchanger.

GEOTHERM-2 continues the work initiate in the GEOTHERM-1 project (2009-2012). The project was conceived in order to provide a bridge to a major nationwide project in geothermal energy, the Swiss Competence Center Energy Research-Supply of Energy (SCCER-SoE), that was in its planning phase when GEOTHERM-2 was proposed, and has begun in the meantime.

In total thirty eight co-workers from various Departments and Institutes in ETH and in EPFL, and of the Paul Scherrer Institute contribute to the project.

The main strength of GEOTHERM-2 is to adopt a cross-disciplinary approach to the challenges mentioned above. The contributions of GEOTHERM-2 in terms of scientific results, capacity building and knowledge transfer are a therefore critical intermediate step towards successful future Pilot and Demonstration projects, and complement the activities conducted in SCCER-SoE.

The research activities in GEOTHERM-2 are organized in six Modules or work packages, which are designed to:

• Develop and test novel observational tools for the geomechanics of reservoir creation;
• Assess and mitigate the risks associated with noticeable induced seismicity;
• Assess potential accidental risks leading to health and environmental impacts as well as public perceptions of risks associated with geothermal energy development;
• Expand a multi-scale – multi-process modeling code for simulating the process of reservoir generation as well as the longer-term evolution of the reservoir during production;
• Investigate the effects of chemical reaction between fluid and rock on long-term permeability evolution and heat extraction from the reservoir;
• Design a decision-support tool for optimizing the use of geothermal energy in cities, by quantifying all interacting factors including geological and economic parameters, conversion efficiency and temporal heat storage, complementary energy sources and societal acceptance.

The exploitation of underground energy resources as well as the use and expansion of hydropower are, like any other energy technology, not risk free. To address this risk, we develop upon the holistic concept of risk governance and community resilience, advocating a broad picture of risk: In addition to risk analysis and risk management, we also investigate how risk-related decision-making unfolds when a range of actors is involved. This requires coordination and possibly reconciliation between a profusion of roles, perspectives, goals and activities. Developments include: a rigorous common methodology and a consistent modelling approach to hazard, vulnerability, risk, resilience and societal acceptance assessment of energy technologies; a stress test framework and its application to assess the vulnerability and resilience of individual critical energy infrastructures, as well as the first level of interdependencies among these infrastructures; standardized protocols, operational guidelines and/or softwares for monitoring strategies, hazard and risk assessment during all project phases (including real-time procedures), and finally for mitigation and related communication strategies.

In phase II, the main activities of the group are in continuation with phase I but with increased interactions with Swiss P&D projects, including industrial ones and research underground labs. New applications are being developed and tested for induced seismicity risk mitigation. Those are also refined based on P&D project feedback. The main innovations in phase II are the testing of more sophisticated traffic-light systems and the inclusion of seismic risk models in economic models (including energy modelling, cost-benefit analyses and decision making under uncertainty). For the latter, interactions with SCCER CREST via a joint activity will help move forward with some legislative recommendations.

Storing CO₂ underground (Carbon Capture and Storage CCS) is one technology among others that reduces emissions above ground and therefore supports the objectives of the Energy Strategy 2050.

Once the CO₂ is stored, it may escape through the borehole used to pump in the CO₂ or through faults in the rock above the reservoir meant to seal it. Those faults might not only influence the long-term containment of CO₂, but also the occurrence of induced micro-seismicity. The presence of faults in the capturing rock therefore strongly affects the site characterization process in terms of safety and risk assessment, monitoring, verification, and with respect to the risk management plan.

To study these aspects, the Swiss Seismological Service and the SCCER-SoE conduct an experiment in close collaboration with the Department of Mechanical and Process Engineering and the Institute of Geophysics at ETH Zurich, with Swisstopo and EPFL, and with scientists from Norway, the Netherlands and the UK. The experiment is part of the ELEGANCY project, which is funded by the EU and the SFOE.

The main goal of the experiment is to understand the relevant processes governing movement of stored CO₂ along faults, the occurrence of micro-seismicity and to contribute to an enhanced site characterization. This involves experimental work at the Mont Terri rock laboratory, where the scientists inject CO₂ enriched salt water into a borehole that cuts through a major fault and monitor how the fault reacts.

To a large part, the seismicity of Switzerland is characterized by swarm-like earthquake sequences of natural, and to a minor extent of man-made origin. Many of these sequences have been studied using relative location techniques, which often allowed to constrain the active fault plane of the larger events in a sequence and shed light on the tectonic processes that drive the seismicity. Yet, in the majority of cases the number of located earthquakes was too small to infer the details of the space-time evolution of the sequences, and their statistical parameters (e.g. magnitude-frequency distribution, Omori parameters). Therefore, it has been largely impossible to resolve clear patterns in the seismicity of individual earthquake sequences that are needed to improve our understanding of the mechanisms behind, and the differences between natural and induced earthquake sequences.

In this project we aim to significantly improve the completeness of detected and located earthquakes in the Swiss catalog. We plan to develop techniques that take advantage of the waveform similarity in natural and induced earthquake sequences to detect seismic events several orders of magnitude below the detection threshold of classical signal energy based detectors. Waveform similarity will than further be exploited to derive accurate and consistent magnitudes and locations for even the smallest events of the sequences.

Building on the data from this analysis we plan to study the processes and physics behind natural and induced microseismicity, e.g.:

• understanding why natural earthquakes occur in swarm-like sequences
• identifying triggering mechanisms of natural and induced earthquake sequences
• understanding the differences and similarities of natural and induced earthquake sequences
• detect and study repeated earthquakes

The processes and conditions underpinning induced seismicity associated with deep geothermal operations are still not sufficiently well understood to make useful predictions as to the likely seismic response to reservoir development and exploitation. The empirical data include only a handful of well-monitored EGS experiments; models are consequently poorly constrained. Unfortunately, datasets of well-monitored deep hydrothermal experiments are missing and empirical constraints of induced seismicity models for these cases do not exist. Given that the majority of the projects underway or planned in Europe are of the hydrothermal type, there is hope that this deficit can be remedied in the near future through a close cooperation of geothermal industry, science and public authorities.

This is where the GeoBest project comes to play. By supporting selected pilot project for a limited time, SED facilitates the dialog with geothermal industry. Besides of the unique opportunity to collect high quality seismic data and being able to access relevant project data, gaining first hand practical experience in this field is of paramour importance for the development of significant best practice guidlines.

Negli ultimi anni il SED ha accompagnato con la sua attività di monitoraggio sismico diversi progetti svizzeri di geotermia di profondità, avviando un dialogo costruttivo con i vari gestori e le autorità cantonali. Sulla base dell’esperienza maturata, il SED ha sviluppato le prime raccomandazioni – rivolte alle autorità cantonali di autorizzazione ed esecuzione – su come gestire la problematica delle sismicità indotta nelle varie fasi di un progetto di geotermia di profondità. Finora queste raccomandazioni si basano però sulle esperienze derivanti da solo pochi progetti ben documentati. Oggi in Svizzera manca ancora l’esperienza pratica con la loro attuazione. È quindi difficile valutare se queste esperienze siano applicabili al contesto locale (geologico, politico, culturale) e quali modifiche si rendano eventualmente necessarie. Un’altra questione importante in questo contesto è valutare in che modo direttive e norme provenienti da altri settori tecnici e ufficiali interagiscono e sono compatibili con le raccomandazioni sismologiche per evitare la sismicità indotta. Spesso i possibili conflitti possono essere individuati e risolti solo durante la messa in pratica del progetto e grazie alla stretta collaborazione dei sismologi con le autorità che rilasciano le autorizzazioni, così come con i gestori degli impianti. Altrettanto importante è il controllo e l’adeguamento periodico di tutte le direttive e norme essenziali sulla base dello stato delle conoscenze acquisito. Quando possibile, ciò dovrebbe avvenire con il consenso di tutti i gruppi di interessati.

Nel corso del progetto Geobest, il SED continuerà quindi a raccogliere, valutare e interpretare gli insiemi di dati di alta qualità e risoluzione sull’origine della sismicità indotta durante i progetti di geotermia di profondità. In questo modo, il SED potrà inoltre offrire un servizio di consulenza e supporto sismologico alle autorità cantonali e federali durante le loro attività di autorizzazione e monitoraggio in tutte le fasi di un progetto di geotermia di profondità. Il SED intende in questo modo contribuire a creare criteri di valutazione standard per l’impatto ambientale che vadano al di là dei limiti cantonali, permettendo così un’uniformazione a breve e a medio termine e quindi un notevole snellimento e accelerazione di questo processo. Un sito web centrale farà in modo che l’opinione pubblica venga informata in modo indipendente, attuale e competente sul tema della sismicità indotta al fine di favorire una discussione oggettiva tra tutti gli interessati.

The goal of this project is the historical-critical revision of the Swiss earthquake catalogue for the pre-instrumental and early instrumental period of systematic earthquake observations in Switzerland, 1878–1963, with a special focus on events of intermediate magnitude reaching epicentral intensities of IV–VI (EMS-98).

To ensure correct interpretation of the large amount of heterogeneous scientific and non-scientific earthquake records, it is essential to investigate the historical, scientific and technological context of their production. This is achieved through the approaches of historical sciences. The proposed work relies on a systematic investigation and a historically sound assessment of the reliability and factuality of historically reported events.

By the use of descriptive primary and secondary sources, macroseismic intensity fields will be established for intermediate-size earthquakes with an intensity in the range IV–VI (EMS-98). This will facilitate the assessment of event parameters such as magnitude, location and depth in a calibrated procedure that will be developed in the project. These parameters are verified by the analysis of the historical seismograms of the Swiss Seismological Service’s early instrumental station network.

Earthquake can initiate subaquatic mass transport and sediment deformation structures, the deposits of which are stored in the sedimentary archive. Due to their good preservation potential and improving dating methods, these earthquake-related deposits in the sedimentary archive of lakes can extend the earthquake catalogue back to prehistorical times. The determination of frequency, epicentre and magnitude of these paleoearthquakes can be a key input for improving a probabilistic seismic hazard model, especially in areas such as Switzerland where strong earthquakes have long recurrence rates and might not be recorded in historic times. In order to better interpret the prehistorical earthquake-related sedimentary record, it remains important to understand which historical earthquakes did trigger mass transport deposits and sediment deformation structures, and which earthquakes did not trigger secondary sedimentary effects in the lake basins.

The proposed project is aimed to improve our understanding of which earthquakes, or what kind of shaking, leave traces in the sediments, in order to evaluate the completeness of the sublacustrine paleoseismological record, using Lake Thun as example. The second aim of this project, directly linked to the first one, is to compare the paleoseismological record with the contemporary national seismic hazard model of Switzerland, updated in 2015. Thus, using the intensity ranges determined in the first part of this project and using the paleoseismic database of Switzerland a systematic analysis of frequencies, sources and magnitudes of possible paleoearthquakes will be compared to time series produced by the seismic hazard model of Switzerland.

The assessment of seismic hazard in regions such as Switzerland are mainly based on historical documents due to the long return periods of medium to large earthquakes. During the last 20 years, seismologists, historians and database experts at the Swiss Seismological Service (SED) at ETH Zurich have been working together on a number of successful interdisciplinary projects.

Within the framework of projects supported by the Swiss National Science Foundation, a wealth of data has been compiled covering information for the pre- and early instrumental period of scientific earthquake monitoring (1880-1963) . The compiled material consists of information collected using very different methods and covers both descriptive and early instrumental data. Due to the wealth of data and the challenges involved in recording and digitizing the very different types of sources, the potential of this data stock has not yet been exploited beyond the basic documentation and interpretation.

This follow-up project, funded by the cogito foundation, serves to maintain the sustainability of the interdisciplinary historical research at the SED through in-depth and systematic analysis, documentation and publication activities. In the seismological domain, the improvement and interconnection of the macroseismic and instrumental data play an important role for the next revision of the earthquake catalogue of Switzerland. In the field of history of knowledge, the development of the SED in the first half of the 20th century can also be used as a data-supported historical case study on the conceptual, organizational and technological development of a scientific institution and its practices

In cooperation with the National Cooperative for the Disposal of Radioactive Waste (Nagra), the Swiss Seismological Service has recently completed the installation of ten new seismological observation stations, three of them including a co-located borehole sensor. The ultimate goal of the project is to densify the existing Swiss Digital Seismic Network (SDSNet) in Northern Switzerland, in order to increase the sensitivity to very-low magnitude events and to improve the accuracy of future location solutions. This is strategic for unbiased monitoring of micro-seismicity at the places of proposed nuclear waste repositories.

At each site, to further improve the quality and usability of the recordings, a full seismic characterization of the area surrounding the installation area was performed. The investigation consisted of a preliminary geological and geotechnical study, followed by an accurate seismic site response analysis by means of state-of-art geophysical techniques. For the borehole stations, in particular, the characterization was performed by combining different types of active seismic methods (refraction tomography, surface wave analysis, Vertical Seismic Profiling, VSP) with ambient vibration based approaches (wavelet decomposition, H/V spectral ratio, polarization analysis, three component f-k analysis).

Results converged to the definition a unique summary velocity profile for the site, later used for the computation of the analytical SH-wave amplification function

Within this project, new signal processing techniques for the analysis of ambient vibrations are developed. The focus is on the development of single-station methods and the adaptation of existing techniques to large arrays.

Single-station methods represent an extremely valuable tool. The use of a single station further simplifies the measurement procedure thus enabling a more time and cost effective survey.

Assumptions on the wavefield used when processing small arrays may be no longer valid when analyzing large arrays. For this reason, we investigate adaptations of existing techniques to large arrays.

Target applications of the methods developed within this project include microzonation studies in Switzerland and investigation of the characteristics of the Swiss Molasse Basin.

Hydrocarbon-bearing geological structures might cause characteristic modifications of the ambient vibration background noise. This question is addressed in a project supported by the Commission for Technology and Innovation (CTI) together with the company SpectraSeis. The link between observations and geological structure can only be made by understanding the wavefield that is recorded. This requires the simultaneous recording and analysis of ambient vibration wave-fields on arrays. Such methods have been developed in the past, and they have been applied to study soft-sediment surface deposits for seismic hazard analysis.

The analysis of all three components of ground motion is addressed. Analysis of such recordings targets to distinguish between standing waves (global resonances) and propagating surface waves (Love- and Rayleigh-waves) as well as body waves (SH and PSV). By adapting array configurations during the measurements in the field, the identification of the wave-types with the corresponding propagation velocity and direction is optimized and allows to determine the source region of the waves and their possible origin. From the wave characteristics, structural information can be inverted that allows to improve structural models. The development of a real-time system for array measurements is part of the project.

The project includes the work of two PhD candidates, addressing practical problems related to source characterization (Falko Bethmann) and site-effect assessment (Valerio Poggi). In the first part of this PhD project, scaling relations between small and large earthquakes are developed and the potential impact of such relations on estimating maximum near-fault ground motions is studied. In the second part of the project, new techniques for site characterization and site response analysis are implemented. First, a new method to analyze three component array recordings of ambient vibration is developed that allows retrieving the ellipticity functions of the different Rayleigh-wave modes. Subsequently, a procedure to combine passive (ambient vibration) and active-source techniques is proposed, with the goal to improve resolution of array measurements on shallow layers from high frequency component of the wave-field. Finally, generic amplification functions are developed for a common reference condition in Switzerland that serve as input for site-specific seismic hazard assessment.

The reliable detection of snow avalanches, landslides and rockfall provides the basis for any advanced investigation on triggering mechanisms, risk assessment or the identification of possible precursors. It is well known that such phenomena produce specific seismic signals. Nonetheless, the manual detection on seismic traces is not feasible since it is extremely time consuming and results are influenced by the subjective view of the analyst. Automatic detection is therefore preferred, as unbiased results are obtained in near real-time. In this project, we will take advantage of an automatic classification procedure for continuous seismic signals to detect avalanches, landslides and rockfalls in continuous streams of seismic data. The applied method is independent of previously acquired data and classification schemes, offering the opportunity to detect very rare and highly variable events.

The goal of this project is to improve the detection across the entire Swiss Alps and to better understand possible triggering mechanisms. In addition accurate information on the number and release time of avalanches will provide an important contribution to the avalanche warning service at the SLF. This research is highly relevant since large scale avalanche and landslide monitoring will provide reliable data for further research, the development of near real-time products and improved risk assessment and warning systems.

Recent discoveries include: Non-volcanic tremors (NVT), strong heterogeneity of the relative stress distribution, temporal and along-fault variable aseismic creep, repeating earthquakes, slow slip events. Based on the insight that was gained from these previous studies, we will be able to develop and calibrate an indicative stress-meter for the Earth’s crust. In this project we link for the first time the statistical analysis of the size distribution of earthquakes with complementary observations of fault movement.

This yields an improved understanding of the nature of fault loading cycles. Therefore, the results will provide key understanding to unravelling the predictability of earthquakes and has the potential to radically change the assessment of local seismic hazard for selected well-understood and well-monitored faults.

Our present knowledge about earthquakes does not yet allow us to reliably forecast earthquakes. Therefore, the study of precursors is an essential step in the direction of earthquake forecasting. Precursors can be anomalous seismic patterns or other phenomena such as peculiar animal behavior, or electromagnetic anomalies etc., which indicate the incidence of a large event. We focus in our studies on seismic precursors, namely quiescence, which is expressed through reduced seismic activity, accelerated seismicity (ASR) and short term foreshocks. The mentioned precursors are observed in many selected earthquake sequences in the past. However, there is skepticism if these precursors happen systematically; some studies explain their occurrence rather as a random temporary perturbation of normal seismicity which is accidentally followed by a large earthquake.

We believe that systematic investigations on the occurrence of precursors give essential evidence for or against their existence. We chose to perform these investigations with statistical tools, hence by evaluating location, time and magnitudes of earthquakes from several regional earthquake catalogs of the world, to obtain representative precursor statistics.

We find that small earthquakes, as they occur more frequently, could facilitate the detection of precursory patterns (Mignan, 2014). We study statistical models used to describe earthquake occurrence and the impact of the choice of the lowest magnitude on them (Seif et al, 2016, submitted). Using these models we evaluate if foreshock occurrence differs from normal seismicity. We also want to specify how often foreshock patterns are followed by large events or not (true/false alarm rate). In the future remaining precursory patterns, quiescence and accelerated seismicity, will be investigated in the same way. We hope that the statistical analysis will allow us to better understand the physical processes which lead to the occurrence of precursors.

Quantifying time-varying seismicity rates is fundamentally important to protecting people who live in areas subject to extreme earthquake shaking. One primary difficulty with such assessment is determining how faults interact. Some recent studies have noted the ability of passing earthquake waves to increase the 'triggerability' of a fault in a delayed form of dynamic stressing: after seismic waves pass, faults are more prone to fail in a subsequent earthquake. The deadly Canterbury earthquake sequence has characteristics that suggest it was promoted by such distant, delayed, dynamic triggering. The sequence is also compatible with a model in which low-strain rate areas are efficient at storing and transferring static stresses. This has implications for earthquake clustering and the generation of damaging ground motion. We will apply recently-developed techniques in concert to address three questions: 1) Can we quantify distant and delayed triggering in this sequence? We will address this by correlating increased geodetic crustal velocities in Canterbury following the 2009 M7.8 Dusky Sound earthquake that occurred hundreds of km away. We will apply source scanning and template matching techniques to search Canterbury for microseismicity that was triggered by the M7.8 event. 2) Do earthquakes in low-strain rate areas exhibit more clustering and longer aftershock sequences than their high-strain rate counterparts, and do these earthquakes produce stronger ground motions? We will build a comprehensive model of earthquake generation in low-strain rate areas by using an earthquake simulator to model the evolution of the sequence. 3) Can the simulator model we develop demonstrate skill in seismicity forecast experiments? The model developed in this project could provide a true step change and bring seismology closer to bridging the gap between probabilistic forecasting and deterministic modelling of earthquake hazard.

Statistical seismology is the application of rigorous statistical methods to earthquake science with the goal of improving our knowledge of how the earth works. Within statistical seismology there is a strong emphasis on the analysis of seismicity data in order to improve our scientific understanding of earthquakes and to improve the evaluation and testing of earthquake forecasts, earthquake early warning, and seismic hazards assessments. Given the societal importance of these applications, statistical seismology must be done well. Unfortunately, a lack of educational resources and available software tools make it difficult for students and new practitioners to learn about this discipline. The goal of the Community Online Resource for Statistical Seismicity Analysis (CORSSA) is to promote excellence in statistical seismology by providing the knowledge and resources necessary to understand and implement the best practices.

CORSSA covers a wide variety of themes:

Introductory Material
Statistical Foundations
Understanding Seismicity Catalogs and Their Problems
Models and Techniques for Analyzing Seismicity
Earthquake Predictability and Related Hypothesis Testing

Each of these themes includes a series of articles that are listed in the CORSSA Table of Contents. The series of themes was devised to make it easy for the reader to focus on their personal requirements to get an introduction to statistical seismology, or to learn about the basics of earthquakes, statistics, and/or the intricacies of seismicity catalogs before moving onto applications.