Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data
The 2005 Mw 8.6 Nias–Simeulue earthquake was caused by rupture of a portion of the Sunda megathrust offshore northern Sumatra. This event occurred within an array of continuous Global Positioning System (gps) stations and produced measurable vertical displacement of the fringing coral reefs above th...
| Main Authors: | , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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2012
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| Online Access: | https://hdl.handle.net/10356/96742 http://hdl.handle.net/10220/8883 |
| _version_ | 1824454711488544768 |
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| author | Konca, A. Ozgun Hjorleifsdottir, Vala Song, Alex Teh-Ru Avouac, Jean-Philippe Ji, Chen Sieh, Kerry Helmberger, Don V. Briggs, Richard W. Meltzner, Aron J. |
| author_facet | Konca, A. Ozgun Hjorleifsdottir, Vala Song, Alex Teh-Ru Avouac, Jean-Philippe Ji, Chen Sieh, Kerry Helmberger, Don V. Briggs, Richard W. Meltzner, Aron J. |
| author_sort | Konca, A. Ozgun |
| collection | NTU |
| description | The 2005 Mw 8.6 Nias–Simeulue earthquake was caused by rupture of a portion of the Sunda megathrust offshore northern Sumatra. This event occurred within an array of continuous Global Positioning System (gps) stations and produced measurable vertical displacement of the fringing coral reefs above the fault rupture. Thus, this earthquake provides a unique opportunity to assess the source characteristics of a megathrust event from the joint analysis of seismic data and near-field static co-seismic displacements. Based on the excitation of the normal mode data and geodetic data we put relatively tight constraints on the seismic moment and the fault dip, where the dip is determined to be 8° to 10° with corresponding moments of 1.24 × 10^22 to 1.00 × 10^22 N m, respectively. The geodetic constraints on slip distribution help to eliminate the trade-off between rupture velocity and slip kinematics. Source models obtained from the inversion of various combinations of the teleseismic body waves and geodetic data are evaluated by comparing predicted and observed long-period seismic waveforms (100–500 sec). Our results indicate a relatively slow average rupture velocity of 1.5 to 2.5 km/sec and long average rise time of up to 20 sec. The earthquake nucleated between two separate slip patches, one beneath Nias and the other beneath Simeulue Island. The gap between the two patches and the hypocentral location appears to be coincident with a local geological disruption of the forearc. Coseismic slip clearly tapers to zero before it reaches the trench probably because the rupture propagation was inhibited when it reached the accretionary prism. Using the models from joint inversions, we estimate the peak ground velocity on Nias Island to be about 30 cm/sec, an order of magnitude slower than for thrust events in continental areas. This study emphasizes the importance of utilizing multiple datasets in imaging seismic ruptures. |
| first_indexed | 2025-02-19T03:26:39Z |
| format | Journal Article |
| id | ntu-10356/96742 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:26:39Z |
| publishDate | 2012 |
| record_format | dspace |
| spelling | ntu-10356/967422020-03-07T12:45:26Z Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data Konca, A. Ozgun Hjorleifsdottir, Vala Song, Alex Teh-Ru Avouac, Jean-Philippe Ji, Chen Sieh, Kerry Helmberger, Don V. Briggs, Richard W. Meltzner, Aron J. DRNTU::Science::Geology::Volcanoes and earthquakes The 2005 Mw 8.6 Nias–Simeulue earthquake was caused by rupture of a portion of the Sunda megathrust offshore northern Sumatra. This event occurred within an array of continuous Global Positioning System (gps) stations and produced measurable vertical displacement of the fringing coral reefs above the fault rupture. Thus, this earthquake provides a unique opportunity to assess the source characteristics of a megathrust event from the joint analysis of seismic data and near-field static co-seismic displacements. Based on the excitation of the normal mode data and geodetic data we put relatively tight constraints on the seismic moment and the fault dip, where the dip is determined to be 8° to 10° with corresponding moments of 1.24 × 10^22 to 1.00 × 10^22 N m, respectively. The geodetic constraints on slip distribution help to eliminate the trade-off between rupture velocity and slip kinematics. Source models obtained from the inversion of various combinations of the teleseismic body waves and geodetic data are evaluated by comparing predicted and observed long-period seismic waveforms (100–500 sec). Our results indicate a relatively slow average rupture velocity of 1.5 to 2.5 km/sec and long average rise time of up to 20 sec. The earthquake nucleated between two separate slip patches, one beneath Nias and the other beneath Simeulue Island. The gap between the two patches and the hypocentral location appears to be coincident with a local geological disruption of the forearc. Coseismic slip clearly tapers to zero before it reaches the trench probably because the rupture propagation was inhibited when it reached the accretionary prism. Using the models from joint inversions, we estimate the peak ground velocity on Nias Island to be about 30 cm/sec, an order of magnitude slower than for thrust events in continental areas. This study emphasizes the importance of utilizing multiple datasets in imaging seismic ruptures. 2012-12-27T03:03:02Z 2019-12-06T19:34:27Z 2012-12-27T03:03:02Z 2019-12-06T19:34:27Z 2007 2007 Journal Article Konca, A. O., Hjorleifsdottir, V., Song, A. T. R., Avouac, J. P., Helmberger, D. V., Ji, C., et al. (2007). Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data. Bulletin of the Seismological Society of America, 97(1A), S307-S322. 0037-1106 https://hdl.handle.net/10356/96742 http://hdl.handle.net/10220/8883 10.1785/0120050632 en Bulletin of the seismological society of America © 2007 Bulletin of the Seismological Society of America. |
| spellingShingle | DRNTU::Science::Geology::Volcanoes and earthquakes Konca, A. Ozgun Hjorleifsdottir, Vala Song, Alex Teh-Ru Avouac, Jean-Philippe Ji, Chen Sieh, Kerry Helmberger, Don V. Briggs, Richard W. Meltzner, Aron J. Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title | Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title_full | Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title_fullStr | Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title_full_unstemmed | Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title_short | Rupture kinematics of the 2005 Mw 8.6 Nias-Simeulue earthquake from the joint inversion of seismic and geodetic data |
| title_sort | rupture kinematics of the 2005 mw 8 6 nias simeulue earthquake from the joint inversion of seismic and geodetic data |
| topic | DRNTU::Science::Geology::Volcanoes and earthquakes |
| url | https://hdl.handle.net/10356/96742 http://hdl.handle.net/10220/8883 |
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