THE 16 APRIL 2015 MW6.1 EARTHQUAKE SEQUENCE NEAR KASOS ISLAND AT THE EASTERN HELLENIC SUBDUCTION ZONE


A.A. Kiratzi
Résumé

Broad band seismic waveforms are used to determine the source model of the 16 April 2015 (UTC 18:07:44) earthquake, Mw6.1, which occurred 14 km SW of Kasos Island, in the eastern Hellenic subduction zone. The mainshock is connected with oblique leftlateral motion on a reverse fault, dipping to SE. Most of the aftershocks are compatible with strike-slip or oblique normal faulting, with the T-axes showing along arc extension. A finite fault slip inversion was performed, allowing for the rake angle to vary across the fault, to capture the variation in the slip vectors. The rupture initiated in the lower crust, at a centroid depth of 23 km, and propagated mainly towards SW. The slip is confined in depth within ~17km and 27km, mainly in a single asperity, with the peak slip of the order of 60 cm. The slip model provided synthetic seismograms which matched satisfactory the observed, and with forward modelling the ShakeMap was calculated. The 2015 Kasos earthquake sequence is compatible with shear motions parallel to the strike of the subduction zone. It provides evidence that part of the deformation in the eastern Hellenic subduction is taken up by the simultaneous operation of reverse faulting and of minor strike-slip and oblique normal faulting, with slip vectors aligned ~ parallel to the Pliny and Strabo Trenches and the long axis of the local bathymetry.

Article Details
  • Rubrique
  • Geophysics and Seismology
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Références
Benetatos, C., Dreger, D. and Kiratzi, A., 2007. Complex and segmented rupture associated with the
August 2003 (Mw 6.2) Lefkada (Ionian Islands) earthquake, Bulletin of the Seismological
Society of America, 97(1B), 35-51, doi: 10.1785/ 0120060123.
Chousianitis, K., Ganas, A. and Evangelidis, C., 2015. Strain and rotation rate patterns of mainland
Greece from continuous GPS data and comparison between seismic and geodetic moment
release, J. Geophys. Res. Solid Earth, 120, doi: 10.1002/2014JB011762.
Dreger, D., 2002. Manual of the Time-Domain Moment Tensor Inverse Code (TDMT_INVC),
Release 1.1, Berkeley Seismological Laboratory, 18 pp.
Dreger, D. and Kaverina, A., 2000. Seismic remote sensing for the earthquake source process and
near - source strong shaking: a case study of the October 16, 1999 Hector Mine earthquake,
Geophys. Res. Lett., 27, 1941-1944.
Hartzell, S.H. and Heaton, T., 1983. Inversion of strong ground motion and teleseismic waveform
data for the fault rupture history of the 1979 Imperial Valley, California, earthquake, Bull.
Seism. Soc. Am., 73, 1553-1583.
Kalogeras, I. and Melis, N., 2015. Preliminary report: The April 16, 2015 Kasos earthquake, SE
Aegean, Greece, 1-10, available at: http://accelnet.gein.noa.gr/strong-earthquake-reports.
Karagianni, E.E., Papazachos, C.B., Panagiotopoulos, D.G., Suhadolc, P., Vuan, A. and Panza, G.F.,
Shear velocity structure in the Aegean area obtained by inversion of Rayleigh waves,
Geophys. J. Int., 120, 127-143.
Kaverina, A., Dreger, D.S. and Price, E., 2002. The combined inversion of seismic and geodetic data
for the source process of the 16 October, 1999 Mw7.1 Hector Mine, California, earthquake,
Bull. Seism. Soc. Am., 92, Special issue on the Hector Mine earthquake, 1266-1280.
Kiratzi, A., 2014. Mechanisms of Earthquakes in Aegean, Encyclopedia of Earthquake Engineering,
Article ID: 382074, ISBN: 978-3-642-36197-5.
Kiratzi, A., Aktar, M. and Svigkas, N., 2013. The 10 June 2012 Mw6.0 earthquake sequence in the
easternmost end of the Hellenic Arc, Bulletin of the Geological Society of Greece, XLVII, ID: 230.
Langston, C.A. and Helmberger, D.V., 1975. A procedure for modelling shallow dislocation
sources, Geophys. J. R. Astr. Soc., 42, 117-130.
Novotny, O., Zahradník, J. and Tselentis, G., 2001. North-western Turkey earthquakes and the
crustal structure inferred from surface waves observed in Western Greece, Bull. Seism. Soc.
Am., 91, 875-879.
McCaffrey, R., Abers, G. and Zwick, P., 1991. Inversion of Teleseismic Body Waves, International
Association of Seismology and Physics of the Earth’s Interior, 166 pp.
Roumelioti, Z., Kiratzi, A. and Benetatos, C., 2011. Time Domain Moment Tensors of Earthquakes
in the broader Aegean Sea for the years 2006-2007: the database of the Aristotle University
of Thessaloniki, J. Geodynamics, doi: 10.1016/j.jog.2010.01.011.pdf.
Saikia, C.K., 1994. Modified frequency - wavenumber algorithm for regional seismograms using Filon’s
quadrature: modelling of Lg waves in Eastern North America, Geophys. J. Int., 118, 142-158.
Shaw, B., 2012. Active Tectonics of the Hellenic Subduction Zone, Springer Theses, 1, doi:
1007/978-3-642-20804-1_1, Springer-Verlag Berlin.
Skarlatoudis, A.A., Papazachos, C.B., Margaris, B.N., Theodulidis N., Papaioannou, Ch.,
Kalogeras, I., Scordilis, E.M. and Karakostas, V., 2003. Empirical peak ground-motion
predictive relations for shallow earthquakes in Greece, Bull. Seism. Soc. Am., 93, 2591-2603.
Skarlatoudis, A.A., Papazachos, C.B., Margaris, B.N., Theodulidis N., Papaioannou, Ch.,
Kalogeras, I., Scordilis, E.M. and Karakostas, V., 2007. Erratum to “Empirical peak groundmotion
predictive relations for shallow earthquakes in Greece”, Bull. Seism. Soc. Am., 97(6),
-2221, doi: 10.1785/0120070176.
Somerville, P.G., 1993. Engineering applications of strong ground-motion simulation,
Tectonophysics, 218, 195-219.
Taymaz, T., Jackson, J. and McKenzie, D., 1991. Active tectonics of the north and central Aegean
Sea, Geophys. J. Int., 106, 433-490.
Wald, D.J. and Allen, T.I., 2007. Topographic slope as a proxy for seismic site conditions and
amplification, Bull. Seism. Soc. Am., 97(5), 1379-1395, doi: 10.1785/ 0120060267.
Wessel, P. and Smith, W.H.F., 1998. New improved version of the Generic Mapping Tools released,
EOS Trans. AGU 79, 579.
Zwick, P., McCaffrey, R. and Abers, G., 1994. MT5 Program, IASPEI Software Library, 4.