NEW INFORMATION FROM SEISMIC ATTENUATION TOMOGRAPHY: APPLICATION TO GUNTUR VOLCANO

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

NEW INFORMATION FROM SEISMIC ATTENUATION
TOMOGRAPHY: APPLICATION TO GUNTUR VOLCANO

Sri Widiyantoro1, Awali Priyono1, Gede Suantika2, Evandi S. Tambunan3, and Andi M.
Adiwiarta3

1Geophysics Research Group, Faculty of Mining and Petroleum Engineering, ITB
2 Study Program of Earth Sciences, Graduate School, ITB
3Study Program of Geophysics, Faculty of Earth Sciences and Mineral Technology, ITB

ABSTRACT

Travel time tomography has become a standard seismological tool for investigating the velocity structure of large tectonic features and volcanoes. More recently, there has been developments in using attenuation tomography (3D mapping of amplitude decay of seismic waves) to gain more information about the physical make-up of these structures. Studies of seismic travel time tomography on regional and local scales for Indonesia have been performed by previous researchers. On the other hand, a comprehensive study of attenuation tomography that exploit the amplitude data has not been done yet. Therefore, we are motivated to carry out a study on seismic attenuation tomography. Here, the Guntur volcano is chosen due to its present-day high seismic activity, long eruption history and its location i.e. close to the densely populated tourist city of Garut in West Java.

The main objective of this study is to construct 3D seismic attenuation models of the Guntur volcano by utilizing seismograms from recent investigations. We have inverted two data sets taken from two separated observation periods. The results have provided a 4D model of the seismic internal structure of the Guntur volcano. The striking observation is that low velocity anomalies that may represent the distribution of magma are associated with strong low Q (high attenuation) anomalies.