Relocation of hypocenters from DOMERAPI and BMKG networks： a preliminary result from DOMERAPI project

作者：Mohamad Ramdhan,Sri Widiyantoro,Andri Dian Nugraha,Jean-Philippe Métaxian,Asep Saepuloh,Said Kristyawan,Andry Syaly Sembiring,Agus Budi Santoso,Antoine Laurin,Ahmad Ali Fahmi

摘要：Merapi volcano located in central Java, Indonesia,is one of the most active stratovolcanoes in the world. Many Earth scientists have conducted studies on this volcano using various methods. The geological features around Merapi are very attractive to be investigated because they have been formed by a complex tectonic process and volcanic activities since tens of millions of years ago. The southern mountain range, Kendeng basin and Opak active fault located around the study area resulted from these processes. DOMERAPI project was conducted to understand deep magma sources of the Merapi volcano comprehensively. The DOMERAPI network was running from October 2013 to mid-April 2015 by deploying 46 broad-band seismometers around the volcano. Several steps, i.e., earthquake event identification,arrival time picking of P and S waves, hypocenter determination and hypocenter relocation, were carried out in this study. We used Geiger's method(Geiger 1912) for hypocenter determination and double-difference method for hypocenter relocation. The relocation result will be used to carry out seismic tomographic imaging of structures beneath the Merapi volcano and its surroundings. For the hypocenter determination, the DOMERAPI data were processed simultaneously with those from the Agency for Meteorology, Climatology and Geophysics(BMKG) seismic network in order to minimize the azimuthal gap. We found that the majority of earthquakes occurred outside the DOMERAPI network. There are 464 and 399 earthquakes obtained before and after hypocenter relocation, respectively. The hypocenter relocation result successfully detects some tectonic features, such as a nearly vertical cluster of events indicating a subduction-related backthrust to the south of central Java and a cluster of events to the east of Opak fault suggesting that the fault has an eastward dip.

发文机构：Study Program of Earth Sciences Agency for Meteorology Global Geophysics Research Group Research Center for Disaster Mitigation ISTerre Faculty of Earth Sciences and Technology Center for Volcanology and Geological Hazard Mitigation

关键词：震源定位网络运行地震事件识别火山活动地震层析成像java构造特征印度尼西亚Earthquake Relocation DOMERAPI BMKG Tectonic feature

分类号： P315.2[天文地球—地震学][天文地球—固体地球物理学][天文地球—地球物理学]TP393.06[自动化与计算机技术—计算机应用技术][自动化与计算机技术—计算机科学与技术]