Analysis of Earthquake Data from the Indonesian Seismograph Network

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Prior to the 2004 Great Sumatra Earthquake, the seismographic network of Indonesia was relatively sparse and generated little data that could be used for earthquake research. Since then, however, Indonesia has developed a modern seismographic network consisting of about 140 broadband stations. These generate high-quality data (Figure 1.) that can be used to shine a light on the occurrence of earthquake in one of the Earth’s largest and most active subduction zones.

ANU has been collaborating with Indonesia’s Agency for Meteorology, Climatology and Geophysics to improve the level of earthquake information extracted from these data. Until now focus has generally been on earthquakes greater than about magnitude 5, since these are the events most likely to cause damage. However, the dataset contains many thousands of smaller earthquakes that have yet to be analysed. These smaller earthquakes have great potential to contribute to our understanding of earthquake occurrence in Indonesia. First, they provide greater spatial coverage for studies of the seismic velocity structure of the Indonesian crust, which can be important for understanding the subduction zone geodynamics and also leads to more accurate hypocenter estimates for all earthquakes. Also, analysis of earthquakes below magnitude 5 is important for understanding the scaling relationships that govern earthquake occurrence in Indonesia. Finally, the locations of smaller earthquakes may help to delineate seismically active structures that have yet to rupture in a larger earthquake.

The aim of this project will be to detect seismic phases in the Indonesian waveform dataset, with the goal of detecting and locating earthquakes below magnitude 5 that have hitherto been ignored. Software tools are available for analysis of the existing waveform database, in particular for detecting seismic phases, locating earthquakes, and estimating magnitude. The student will learn about the propagation of seismic  waves and how they are used to study earthquakes.

Figure 1. Vertical components of broadband seismic waveforms recorded following the 2009 Kerinic earthquake (Mw=6.6) in Sumatra. Seismograms are plotted in order of increasing distance from the earthquake downwards, so that the relative times of the various seismic waves are clearly evident.

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