Source study of the 1996 MW 8.2 Biak (Papua, Indonesia) earthquake: relations to regional tectonics and directivity effect

The northern region of Cenderawasih Bay is a subduction zone segment of the Micro-Caroline Ocean plate with the Australian Continental Plate. Some tsunamigenic earthquakes had been recorded here in 1914 and 1996; however, the source characteristics and seismogenesis are not well investigated. In thi...

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Bibliographic Details
Published in:Arabian journal of geosciences 2021-10, Vol.14 (20), Article 2151
Main Authors: Arimuko, Abraham, Sianipar, Dimas
Format: Article
Language:English
Subjects:
Amplitude
Amplitudes
Direction
Directivity
Earth and Environmental Science
Earth science
Earth Sciences
Earthquakes
Original Paper
P waves
Plates (tectonics)
Radiation
Segments
Seismic activity
Source studies
Subduction
Subduction (geology)
Subduction zones
Tectonics
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Summary:The northern region of Cenderawasih Bay is a subduction zone segment of the Micro-Caroline Ocean plate with the Australian Continental Plate. Some tsunamigenic earthquakes had been recorded here in 1914 and 1996; however, the source characteristics and seismogenesis are not well investigated. In this study, we perform earthquake source modeling and directivity analysis. A finite fault model is obtained to determine the asperity location through body-wave inversion. This study found a distinct segment on the southern part of the subduction that ruptured the 1996 earthquake and extending westward and might be related to the rupture of the previous earthquake. The directivity effect can be seen from the amplitude and the time it takes to reach the highest amplitude ( T r ) relative to the P-wave’s arrival time ( P 0 ). The vertical component’s directivity is affected by source propagation, whose direction depends on the rake. Besides, the radiation pattern also affects the directivity. On the other hand, the SH component has the largest energy emission direction on the side with the direction and opposite to the strike to show the fault plane’s orientation. We demonstrate that the upward-dip source mechanism in the Biak earthquake showing the directivity effect is different from the other mechanism, such as the strike-slip earthquake.
ISSN:1866-7511
1866-7538
DOI:10.1007/s12517-021-08560-8