Earthquakes can be of natural, tectonic origin or be triggered by human activity. The latter are called induced quakes. They can occur in connection with large-scale technical interventions in the geological underground.
Seismograms of induced earthquakes are no different from those of natural earthquakes. A number of indicators provide information about the origin of earthquakes. These include the spatial distribution of the quakes, their depth and how closely they occur in time to interventions in the geological underground. For this reason, no categorisation can be carried out as a result of automatic assessment. In manual assessment, an earthquake is categorised by default as an earthquake of natural origin. Only after additional testing can the category change and an earthquake be referred to as 'induced'.
The categorisation of earthquakes as natural or induced is based on the best information available at the time of assessment. The categorisation is shown in the 'Earthquake Type' column and is always subject to some uncertainty. The SED follows international, publicly available guidelines for categorisation (see E-PIE scheme). However, the categorisation is based on the judgement of experts. If further data becomes available at a later date, a reassessment may take place and an earthquake that was initially categorised as 'induced' may be classified as 'natural' again.
The SED does not distinguish between 'induced' and 'triggered' earthquakes, although these terms are sometimes used to indicate whether human activities are considered to be primarily responsible or only marginally responsible for an earthquake. This is because of the substantial uncertainty surrounding this and the lack of a scientific consensus as to whether making such a distinction is even meaningful or possible.