Relocation and focal mechanisms of the 2016 ML 6 6 Meinong Taiwan earthquake sequence

Abstract

Three moderate earthquakes occurred in southwestern Taiwan in the last 7 years all displayed mid- to lower- crustal focal depth similar focal mechanisms with NWW striking north dipping plane and ENE-WSW compression The aftershocks of the 2016 Meinong earthquake were not only restricted to the main shock area but also reached as far as 30 km away in the Tainan area According to waveform-HypoDD result earthquakes in the mainshock area displayed two clusters with different faulting style One included the mainshock ruptured along a shallow dipping fault plane which is consistent with the dip of mainshock focal mechanism about 10? at initial rupture and the other showed normal faulting on a north steep dipping plane Events in Tainan all concentrated at 23-26 km depth and we inferred that these events as the subduction interface seismicity Moreover the T-axis of seismicity in Central Range is sub-parallel to the P-axis of mainshock which indicating the extension on hanging wall of mainshock fault The offshore events presented normal faulting that implying the activation of pre-existing normal faults and the area was still undeformed by convergence We conclude that these mid-crust earthquake sequences occurred with similar focal mechanisms were resulted from the inversion of inherited normal fault which is likely to be connected to the Chishan transfer fault zone (ChiTFZ) in the southwestern Taiwan fold-and-thrust belt the offshore structures represent the activation of pre-existing normal fault which triggered by the Meinong earthquake These moderate earthquakes sequences are evidently basement-involved thrust faulting events in southwestern Taiwan

Date of Award	2017 Aug 22
Original language	English
Supervisor	Ruey-Juin Rau (Supervisor)