A Cross-Correlation Technique for Relocation of Seismicity in the Western Corinth Rift

Abstract

Local seismological networks provide data that allow the location of microearthquakes which

The 2013 earthquake swarm in Helike, Greece: seismic activity at the root of old normal faults

“…Events were grouped in multiplets according to their waveform similarity, using a correlation threshold C th = 0.80, an optimal value which maximized the difference between the size of the largest multiplet and the sum of correlated events (Kapetanidis et al 2010). This resulted in 113 multiplets containing a total of 1189 events (∼80 per cent of the catalogue).…”

“…The intense swarm of 2001 near station AIOA (Agios Ioannis village) has been attributed to this fault, which is roughly parallel to the orientation of the Hellenic napes and is characterized as a structure that is cross-cutting the currently active N100 • E trending faults (Lyon-Caen et al 2004;Lambotte et al 2014). This hypothesis has been based on the geometry of the best-fit plane indicated by the relocated spatial distribution of that swarm (Kapetanidis et al 2010;Pacchiani & Lyon-Caen 2010), as well as the FM solution of its major event (Zahradnik et al 2004) and was also suggested to have been triggered by fluids, originating approximately at Kerinitis river (Pacchiani & Lyon-Caen 2010).…”

“…The background seismicity of the gulf and the episodic swarms or clusters of activity are being recorded by the local Corinth Rift Laboratory (CRL) network since 2000 (Lyon-Caen et al 2004). (Lambotte et al 2014), black open circles represent selected seismicity of the period July-August 1991 (Rigo et al 1996), green circles represent the relocated epicentres of the 2001 swarm near Agios Ioannis (Lyon-Caen et al 2004;Kapetanidis et al 2010) and blue circles represent the relocated epicentres of the 2013 swarm (this study). Local stations are displayed with yellow triangles.…”

Spatiotemporal patterns of microseismicity for the identification of active fault structures using seismic waveform cross-correlation and double-difference relocation

“…This can be done e.g. by fitting a 2 nd degree polynomial (Deichmann & Garcia-Fernandez, 1992;Schaff et al, 2004) or using non-linear spline interpolation, either on XC(d) or on the waveforms themselves Lin et al, 2007;Kapetanidis et al, 2010). The latter method is mostly adopted in the present work, as it has been widely tested in various applications of hypocentral relocation with satisfactory results.…”

“…The mean spectral coherence, m coh , can provide additional weighting information (Kapetanidis & Papadimitriou, 2011;Section 4.3). However, it is not practical or robust enough to be a primary similarity measure, as, besides the problems with the calculation of the time-lag from the cross-spectral phase, m coh saturates faster than the corresponding XC max , as similarity decreases (Kapetanidis, 2007;Kapetanidis et al, 2010).…”