DETERMINATION OF CRUSTAL STRUCTURE BENEATH A BROADBAND STATION IN MALAYSIA USING RECEIVER FUNCTION ANALYSIS.
Supervisor: Tatsuhiko HARA
We performed receiver function analyses in order to investigate crust structure beneath a broadband seismic station in Malaysia. We selected 11 teleseismic events from the Malaysian National Seismic Network Database whose magnitudes are in the range between 5.8 and 7.1 with good signal-to-noise ratios. We compared the observed receiver functions to the synthetic receiver functions computed for a model for the site of station IPM taken from the global crust model, CRUST 2.0. There is a significant difference between them. This is likely to be due to the thin sedimentary layer in the crust model, and our comparison suggests that such a sedimentary layer does not exist beneath the station site. Then, we applied a genetic algorithm to perform inversion. We modeled the crust and uppermost upper mantle with six major layers: sediment layer, basement layer, upper crust, middle crust, lower crust and uppermost mantle. The Moho depth is relatively well constrained and is estimated to be about 35km. The thin sedimentary layer is not obtained in the inversion result, although a thin layer with relatively low S wave velocity is obtained. This study is a preliminary attempt to determine velocity structures and obtain an appropriate velocity model for Malaysia. Further accumulation of data and stacking using a larger dataset will be useful to construct such a model by application of the data analysis procedure of this study.
|Citation: ||Bulletin of IISEE, 45, 19-24.|