Problematic non-double-couple mechanism of the 2002 Amfilochia Mw5 earthquake, Western Greece |
| |
| Authors: | Petra Adamova Efthimios Sokos Jiri Zahradnik |
| |
| Institution: | (1) Academy of Sciences, Institute of Geophysics, Prague, Czech Republic;(2) Seismological Laboratory, University of Patras, Patras, Greece;(3) Institute of Geodynamics, National Observatory of Athens, Athens, Greece;(4) Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic |
| |
| Abstract: | Two seismic agencies reported a very low double-couple percentage (DC%) of the Amfilochia earthquake, of about 30% and 60%,
by Schweizerischer Erdbebendienst and Mediterranean Very Broadband Seismographic Network, respectively. Near-regional waveforms,
carefully analyzed in this paper for the DC%, suggested a higher DC%, ranging from 75 to 100, dependent on the uncertainty
of the source position (optimum value DC% = 93). Using a statistical F test, forward modeling of the near-regional data with a single-event low-DC% source yields a significantly worse waveform
match. The fit of near-regional data can be further improved (although at the 90% significance level only) when considering
a speculative two-event model. The same model, when viewed at the very-low frequency range, reaches the very low DC% values.
However, two features make the two-event model unlikely: The two subevents strongly differ in their focal mechanism, and their
mutual separation (3.5 s) is larger than the expected duration of this earthquake. Therefore, the two-source model appears
to be nothing but an interesting equivalent representation of the non-DC model, providing some insight into the possible origin
of the apparently low DC%. Preference is given to the simple interpretation, most clearly supported by the near-regional data,
that the Amfilochia earthquake was an almost pure-shear event. |
| |
| Keywords: | Moment tensor Iterative deconvolution Regional data Waveform inversion Deviatoric solution Source complexity Focal mechanism |
| 本文献已被 SpringerLink 等数据库收录！ |
|
