Inversion of explosive and teleseismic data for two-dimensional velocity structure beneath southern Taiwan
Abstract
While relative arrival times of teleseismic events represent integrated effects of receiver-side velocity anomalies, the arrival times of wide-angle reflection enable us to constrain exclusively the shallow velocity structure. As a result, the deeper velocity structure is better resolved with teleseismic observations when combined with wide-angle reflection traveltimes. We thus conduct a joint inversion for two-dimensional velocity structure beneath southern Taiwan, using data both from the land-based active source during the Taiwan Integrated Geodynamics Research (TAIGER) project and from the Tonga-Kermadec deep earthquakes. The Pg phases of the four active explosions in southern Taiwan as recorded by a linear array of around 580 Texan instruments across southern Taiwan are identified and arrival times picked. The maximum offset distance is about 120 km. The teleseismic data are recorded by a nearly co-linear array of 25 broadband stations. The relative arrival times of all observable P, pP, and sP phases from six Tonga deep earthquakes are determined by the genetic algorithm with the cost function based on sum of cross- correlation over each pair stations. Topographic effects of all stations are considered. We then apply the Fast Marching Tomography (FMTOMO) Package (Rawlinson et al., 2006) to invert the two-dimensional velocity beneath southern Taiwan, which best fits both datasets. Preliminary results show that the velocities at shallow depth (less than 10 km) are faster beneath the eastern Taiwan than those beneath the western Taiwan. There is also a low velocity zone beneath Central Range at greater depth. The result will be refined by adding more observations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.T31C2021C
- Keywords:
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- 7200 SEISMOLOGY;
- 7270 Tomography (6982;
- 8180);
- 8100 TECTONOPHYSICS;
- 8102 Continental contractional orogenic belts and inversion tectonics