Very broadband seismic analysis of the 1992 Flores, Indonesia, earthquake (Mw = 7.9)

Abstract

The December 12, 1992, Flores Island earthquake is located in the back arc of the transition zone between the Sunda and Banda arcs, a region in active collision with the Australian continental margin. The earthquake is studied using four seismological techniques spanning a period range of 1-1000 s. The Flores event may be characterized as a shallow back arc thrust with fault plane strike 70° ± 30°, dip 28° ± 10° and rake 80° to 140°, a rupture consisting of three discrete pulses with a total duration of 70 s and an estimated moment release between 7.5 × 1020 and 8.0 × 1020 N m. From the slip vector it is infered that compressional forces play an important role in the deformation mechanism of the back arc north of Flores Island. -Authors