Geodetic slip rate and locking depth of east Semangko Fault derived from GPS measurement

Abstract

65 km Semangko Fault is part of southern segments of Sumatran Fault Zone (SFZ) which is complex corresponds to the transition from the strike-slip regime of the SFZ to the normal faulting tectonics of the Sunda Strait. The recent publication showed branches of Semangko Fault: West Semangko Fault (WSF) and East Semangko Fault (ESF). This study estimated geodetic slip rate and locking depth of ESF using Global Positioning System (GPS) time series data from 2007 to 2019 from all available GPS sites. GPS velocities refer to Sundaland Plate were used to estimate the fault parameters of the WSF and ESF simultaneously. Non-uniformity of velocity direction shows the complexities of Semangko Fault possibly caused by the contribution of all faults around ESF. An ESF geodetic slip rate, which is 12.5 ± 2 mm/yr was lower than WSF, which is 16.5 ± 2 mm/yr. It is consistent with the rigid block nature of the SFZ system as northern segment slip rates have similar value. Small slip rates are possibly leading to lower generated seismic moment than the major segment of SFZ.