In the Otaniemi geothermal project of St1, geophones installed in the bedrock of the Helsinki Metropolitan area discovered in the evening 1.24 magnitude micro-earthquake in the deep bedrock.
The effects of this magnitude have been detectable at ground level in the surrounding areas for example in the form of sound and sound waves can also resonate eg. in windows and structures, but do not cause a risk to humans or damage structures.
The Institute of Seismology has monitored 0.6 magnitude micro-event. The differences in the measurement result is due to differences in measurement methods and equipment. The St1 equipment is tuned to detect water movements as accurately as possible.
Inducing micro-vibration with stimulation is a key part of constructing a geothermal heat plant, as only it can be used to investigate the water flow required for heat production in the deep bedrock. St1 implements the stimulation in a highly controlled manner and according to the measures required by the authorities. We communicate all micro-events exceeding 1.2 magnitudes at our project website.
The target is to finish the stimulation stage today.
Geophone measurement results as well as up to date information can be monitored online www.st1.eu/geothermal-heat
All seismic events in Finland and adjacent areas can be monitored at the Institute of Seismology www.seismo.helsinki.fi/bulletin/list/alert/current_map.html
If you have made earthquake observations yourself, you can report them to Institute of Seismology using the observation form: https://elomake.helsinki.fi/lomakkeet/89816/lomake.html