Triemli Network

The Triemli Network was operated from August 2009 to August 2010 under the contract with Elektrizitätswerke Zürich. The purpose of the network was to monitor induced seismicity related to the deep geothermal drilling project Triemli in the city of Zurich.

Network

To improve the detection capability and location accuracy in the city of Zurich the local Triemli network was operated from August 2009 to August 2010. The network consisted of four stations, of which three were installed at the surface and one station was installed in a 200 m deep borehole. These stations were installed in the city of Zurich and surrounding villages at 1-10 km distance (Figure 1). Stations were installed close to existing buildings to benefit from existing infrastructure (electricity and telephone).

Stations were equipped mainly with short-period sensors (Lennartz LE-3D 1s), except for station EWZT1 (Figure 1) that was equipped with a strong-motion sensor (Kinemetrics EpiSensor) due to the expected high noise-level in the city. Station EWZT0 (Figure 1) was installed in a 200 m deep borehole to improve the signal-to-noise ratio close to drillsite. Data were recorded using Nanometrics Taurus digitizers. Data from all stations were streamed in real-time via ADSL to the SED data center in Zurich. Data were merged with data of permanently installed stations to allow for real-time detecing and location of possible earthquakes. A map showing the stations is shown below. Photos of the installation can be found on the right.

The network was dismantled in August 2010 after the deep geothermal project Triemli was stopped due to the lack of water at sufficient high temperature and flow rate.

Figure 1. Location of stations in the Triemli network. Station EWZT0 was installed in a 200 m deep borehole; stations EWZT1-3 were installed at the surface. Different seismic sensors were used as marked by different colors.

Earthquake Activity

During the operation of the network no earthquakes were recorded that could be associated with the deep geothermal drilling project Triemli.