Surface deformation and earthquake potential in Surabaya from GPS campaigns data

Abstract

Abstract Study by the National Centre for Earthquake Studies suggests the presence of two segments of Kendeng active fault, namely Surabaya fault and Waru fault in Surabaya. This study aims to investigate the surface deformation and earthquake potential in Surabaya that possibly related to the activities of those two faults. We use GPS campaigns data conducted in March 2017, September 2017, May 2018, and October 2018 and five GGPS CORS stations around Surabaya provided by the Indonesian Geospatial Information Agency. In total, 21 GPS stations data were processed to obtain horizontal and vertical displacement velocities in each station. The results showed almost all stations move toward southeast with the velocity rates range from 1.034 cm/yr to 5.674 cm/yr, except BM33 and SB07 that moves northeast with the velocity rates 4.065 cm/yr and 3.312 cm/yr respectively. For the vertical displacements, almost all stations subject to subsidence with the rates range from -0.190 cm/yr to -5.769 cm/yr. Only three stations subject to uplift namely BM23 with the rate of 0.234 cm/yr, BM24 with the rate of 2.844 cm/yr, and BM29 with the rate of 3.33 cm/yr. The strain analyses showed large shortenings in the area between two faults with the values up to 11.95 μstrain. From the results, we can conclude that the surrounding area of the two faults have different deformation patterns, and by confirming with geological data, we suggest that Surabaya has an earthquake potential due to the active faults.