SERA TA Project # 31

Title of Project:
Seismic tremor detection in Greece using small aperture arrays
Hosting Research Infrastructure:
NORSAR

No. of Users:
1

Team Leader:
National and Kapodistrian University of Athens
Vasileios Kapetanidis

Team:


Summary of Project:

The main objective of this research proposal is to detect tremors of tectonic origin in Greece using seismic arrays and array data processing techniques.  This type of signal is usually associated with slow-slip events, which have been mostly observed in several subduction zones worldwide. In Greece no such tremor recordings have ever been documented. There are, however, two candidate zones where they could possibly occur: the Hellenic Arc subduction zone, where the observed strain is mostly accommodated aseismically, and the western Corinth Rift. In the latter case, a strain transient associated with a slow-slip event was observed in December 2002, while there is evidence of creeping that occurs on a developing detachment within the brittle-ductile transition zone.
In the proposed research, an array that consists of 7 broadband seismometers, installed near the town of Magoula, at the western margin of the Corinth Rift, will be employed to detect tremors that may have occurred in the region using beamforming techniques. Candidate signals will be evaluated using a conventional method, such as envelope cross-correlation, at the stations of the local Corinth Rift Laboratory (CRL) network. The developed methodology will be also applied to another seismic array, composed of 9 stations, that is installed in Pylos, South Peloponnese, in collaboration with the National Observatory of Athens. This could target the SW portion of the Hellenic Arc, where tectonic tremors are more likely to be observed, but may be more difficult to evaluate due to the sparse distribution of stations of the regional Hellenic Unified Seismological Network (HUSN). The detection of tectonic tremors in Greece could reveal sites where slow-slip occurs, explaining part of the aseismically accommodated strain and could have implications on the seismic hazard assessment.