The Waveform Inversion of Mainshock and Aftershock Data of the 2006 M6.3 Yogyakarta Earthquake

Abstract

This research was examines the focal mechanism associated with the mainshock and three aftershocks of the magnitude 6.3 Yogyakarta earthquake on May 27, 2006. This study, therefore, aims to provide a cleareranswer on the source mechanism of the earthquake, which has been debated. Data were obtained from the mainshock and aftershock sources, on June 8, 9, and 16, 2006. The mainshock and three aftershocks were used to conduct waveform inversion by calculating the Green's functions through the extended reflectivity method of the near-field and the far-field signal component. The mainshock's focal mechanism has a strike, dip, and range angle of 243.40o, 77.50o, and -28.30o, respectively.Furthermore, the mainshock is not a pure strike-slip as previously hypothesized. The focal mechanism for the aftershock earthquake source on Mw 4.4, obtained on June 8, had a strike, dip, rake, and variance of 192.20o, 29.70o, -48.30o and 0.22, respectively. This aftershock had a different segment from the mainshock event and those obtained on the 9 and 16 of June with the same type of faulting as the mainshock with variance values of 0.195 and 0.243. These results showed that the mainshock of May 27, 2006, activated the aftershock on June 8, with a different type of fault.

A Preliminary Earthquake Detection from The Seismic Temporary Network in The Opak Fault

“…In the last decades, some researches have been studied to figure the source location of the 2006 earthquake and the detailed structure of the Opak fault. Most researchers highlighted to have believed the earthquake did not occurred by the geological structure from the active fault along the Opak River due to the aftershock distribution that mostly located in the easter part [3][4][5][6][7] Figure 1. The tectonic map that shows 23 active faults with potential magnitude and geodetic slip rate in the Aceh Province.…”

“…Some studies also figure the potential of a branched and minor fault were triggered by the seismic activities in the eastern part [8]- [10]. There are many factors have been studied by researchers to highlight the phenomena, for exampleseismometer networks before 2006 to capture the microearthquake activities near the Opak fault [11], [12].…”