Details

Autor(en) / Beteiligte

• Himematsu, Yuji
• Furuya, Masato

Titel

Fault source model for the 2016 Kumamoto earthquake sequence based on ALOS-2/PALSAR-2 pixel-offset data: evidence for dynamic slip partitioning

Ist Teil von

• Earth, planets, and space, 2016-10, Vol.68 (1), p.1, Article 169

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Springer Nature - Complete Springer Journals

Beschreibungen/Notizen

• Series of earthquakes including three M w  > 6 earthquakes occurred in Kumamoto prefecture in the middle of the Kyushu island, Japan. In order to reveal the associated crustal deformation signals, we applied offset tracking technique to ALOS-2/PALSAR-2 data covering three M w  > 6 earthquakes and derived the 3D displacements around the epicenters. We could identify three NE–SW trending displacement discontinuities in the 3D displacements that were consistent with the surface location of Futagawa and Hinagu fault system. We set three-segment fault model whose positions matched the displacement discontinuities, and estimated the slip distributions on each segment from the observed pixel-offset data. Whereas right-lateral slip was dominant in the shallower depth of the larger segments, normal fault slip was more significant at a greater depth of the other segment. The inferred configuration and slip distribution of each segment suggest that slip partitioning under oblique extension stress regime took place during the 2016 Kumamoto earthquake sequence. Moreover, given the consistent focal mechanisms derived from both the slip distribution model and seismology, the significant non-double couple components in the focal mechanism of the main shock are due to simultaneous ruptures of both strike-slip and normal faulting at the distinct segments. Graphical abstract Using ALOS-2/PALSAR-2 pixel-offset data, Himematsu and Furuya (2016) derived 3D displacements associated with the 2016 Kumamoto earthquake sequence. The 3D displacements revealed three major discontinuities, where we set the top edge of the three segments of our fault source model. The inferred slip distribution indicates that significant strike-slip and normal fault slip occurred separately at distinct segments. Moreover, the non-double couple parameter based on our slip distribution model turns out to be consistent with the seismological estimate, suggesting that dynamic slip partitioning occurred during the main shock.