Spatiotemporal evolution of seismic and aseismic slip on the Longitudinal Valley Fault, Taiwan
Abstract
The Longitudinal Valley Fault (LVF) in eastern Taiwan is a high slip rate fault (about 5 cm/yr), which exhibits both seismic and aseismic slip. Deformation of anthropogenic features shows that aseismic creep accounts for a significant fraction of fault slip near the surface, whereas a fraction of the slip is also seismic, since this fault has produced large earthquakes with five M_w>6.8 events in 1951 and 2003. In this study, we analyze a dense set of geodetic and seismological data around the LVF, including campaign mode Global Positioning System(GPS) measurements, time series of daily solutions for continuous GPS stations (cGPS), leveling data, and accelerometric records of the 2003 Chenkung earthquake. To enhance the spatial resolution provided by these data, we complement them with interferometric synthetic aperture radar (InSAR) measurements produced from a series of Advanced Land Observing Satellite images processed using a persistent scatterer technique. The combined data set covers the entire LVF and spans the period from 1992 to 2010. We invert this data to infer the temporal evolution of fault slip at depth using the Principal Component Analysis-based Inversion Method. This technique allows the joint inversion of diverse data, taking the advantage of the spatial resolution given by the InSAR measurements and the temporal resolution afforded by the cGPS data. We find that (1) seismic slip during the 2003 Chengkung earthquake occurred on a fault patch which had remained partially locked in the interseismic period, (2) the seismic rupture propagated partially into a zone of shallow aseismic interseismic creep but failed to reach the surface, and (3) that aseismic afterslip occurred around the area that ruptured seismically. We find consistency between geodetic and seismological constraints on the partitioning between seismic and aseismic creep. About 80–90% of slip on the southern section of LVF in the 0–26 km, seismogenic depth range, is actually aseismic. We infer that the clay-rich Lichi Mélange is the key factor promoting aseismic creep at shallow depth.
Additional Information
© 2014 American Geophysical Union. Received 16 AUG 2013; Accepted 26 APR 2014; Accepted article online 2 MAY 2014; Published online 9 JUN 2014. M.T. thanks the Keck Institute for Space Studies and the Centre National dEtude Spatiales for funding her graduate fellowship. The PALSAR data were provided by the Japan Aerospace Exploration Agency (JAXA) in the scope of PI 1120001 project, and this project was supported by the Gordon and Betty Moore Foundation through Grant GBMF 423.01 to the Tectonics Observatory. This is Tectonics Observatory contribution 261.Attached Files
Published - jgrb50673.pdf
Supplemental Material - readmefile_supp_R2.pdf
Supplemental Material - supplements_R2.pdf
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Additional details
- Eprint ID
- 49023
- Resolver ID
- CaltechAUTHORS:20140828-130315677
- Keck Institute for Space Studies (KISS)
- Centre National d'Études Spatiales (CNES)
- GBMF 423.01
- Gordon and Betty Moore Foundation
- Created
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2014-08-29Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Keck Institute for Space Studies, Caltech Tectonics Observatory, Seismological Laboratory, Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Tectonics Observatory
- Other Numbering System Identifier
- 261