Ambient Noise Tomography of Merapi Complex, Central Java, Indonesia: A Preliminary Result

Abstract

Mt. Merapi is one of the most active and hazardous volcanoes not only in Indonesia but also in the world. Having a height of about 2968 meter above sea level it contains an active lava dome, which regularly produces pyroclastic flows and is categorized as a stratovolcano. It erupts on average every 2-5 years, in which thousands of people live on the flanks of the volcano. The last eruption occurred on 26 October 2010 and after the large eruption in 2010 the characteristic of Mt. Merapi was changed. Due to its uniqueness, Merapi is closely monitored by the many geoscientists, particularly through volcanological surveys.This study is concerned with the application of ambient noise tomography (ANT) to create Rayleigh wave group velocity maps around Mt. Merapi. The continuous data set is taken from the DOMERAPI project, which consists of temporary seismic array of 40 broadband seismometers for approximately ten months. The resulting group velocity maps of Rayleigh wave show an anomaly pattern that agrees with previous geological and geophysical study results. A pronounced, positive anomaly is clearly imaged with direction about 152°N beneath Mt. Merapi through to Mt. Merbabu. In addition, negative anomalies are observed in its east and west flanks.