Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods
Sequences of earthquakes are commonly represented as a succession of periods of interseismic stress accumulation followed by coseismic and postseismic phases of stress release. Because the recurrence time of large earthquakes is often greater than the available span of space geodetic data, it has be...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2014
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| Online Access: | https://hdl.handle.net/10356/102071 http://hdl.handle.net/10220/18854 |
| _version_ | 1811695036898738176 |
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| author | Barbot, Sylvain Agram, Piyush De Michele, Marcello |
| author2 | School of Physical and Mathematical Sciences |
| author_facet | School of Physical and Mathematical Sciences Barbot, Sylvain Agram, Piyush De Michele, Marcello |
| author_sort | Barbot, Sylvain |
| collection | NTU |
| description | Sequences of earthquakes are commonly represented as a succession of periods of interseismic stress accumulation followed by coseismic and postseismic phases of stress release. Because the recurrence time of large earthquakes is often greater than the available span of space geodetic data, it has been challenging to monitor the evolution of interseismic loading in its entire duration. Here we analyze large data sets of surface deformation at different key episodes around the Cholame, Parkfield and creeping segments of the San Andreas Fault that show evidence of significant deceleration of fault slip during the interseismic period. We compare the average fault slip rates before and after the 2004 Mw6 Parkfield earthquake, in the 1986–2004 and 2006–2012 periods, respectively, avoiding 2 years of postseismic deformation after 2004. Using a combination of GPS data from the Plate Boundary Observatory, the Southern California Earthquake Center Crustal Motion Map and the Bay Area Velocity Unification networks and interferometric synthetic aperture radar from the Advanced Land Observing Satellite (ALOS) and Envisat satellites, we show that the area of coupling at the transition between the Parkfield and Cholame segments appears larger later in the interseismic period than it does earlier on. While strong plate coupling is uniform across the Parkfield and Cholame segments in the 1986–2004 period, creep occurs south of the 2004 epicenter after 2006, making segmentation of the San Andreas Fault south of Parkfield more clearly apparent. These observations indicate that analyses of surface deformation late in the earthquake cycle may overestimate the area of plate coupling. A fault surface creeping much below plate rate may in some case be a region that does not promote earthquake nucleation but rather just be at a slower stage of its evolution. Our analysis also shows signs of large variation of slip velocity above and below plate rate in the creeping segment indicating that cycles of weakening and hardening can also be at play in dominantly aseismic areas. |
| first_indexed | 2024-10-01T07:17:05Z |
| format | Journal Article |
| id | ntu-10356/102071 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:17:05Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | ntu-10356/1020712023-02-28T19:43:50Z Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods Barbot, Sylvain Agram, Piyush De Michele, Marcello School of Physical and Mathematical Sciences DRNTU::Science::Physics::Meteorology and climatology Sequences of earthquakes are commonly represented as a succession of periods of interseismic stress accumulation followed by coseismic and postseismic phases of stress release. Because the recurrence time of large earthquakes is often greater than the available span of space geodetic data, it has been challenging to monitor the evolution of interseismic loading in its entire duration. Here we analyze large data sets of surface deformation at different key episodes around the Cholame, Parkfield and creeping segments of the San Andreas Fault that show evidence of significant deceleration of fault slip during the interseismic period. We compare the average fault slip rates before and after the 2004 Mw6 Parkfield earthquake, in the 1986–2004 and 2006–2012 periods, respectively, avoiding 2 years of postseismic deformation after 2004. Using a combination of GPS data from the Plate Boundary Observatory, the Southern California Earthquake Center Crustal Motion Map and the Bay Area Velocity Unification networks and interferometric synthetic aperture radar from the Advanced Land Observing Satellite (ALOS) and Envisat satellites, we show that the area of coupling at the transition between the Parkfield and Cholame segments appears larger later in the interseismic period than it does earlier on. While strong plate coupling is uniform across the Parkfield and Cholame segments in the 1986–2004 period, creep occurs south of the 2004 epicenter after 2006, making segmentation of the San Andreas Fault south of Parkfield more clearly apparent. These observations indicate that analyses of surface deformation late in the earthquake cycle may overestimate the area of plate coupling. A fault surface creeping much below plate rate may in some case be a region that does not promote earthquake nucleation but rather just be at a slower stage of its evolution. Our analysis also shows signs of large variation of slip velocity above and below plate rate in the creeping segment indicating that cycles of weakening and hardening can also be at play in dominantly aseismic areas. Published version 2014-02-24T12:42:24Z 2019-12-06T20:49:15Z 2014-02-24T12:42:24Z 2019-12-06T20:49:15Z 2013 2013 Journal Article Barbot, S., Agram, P., & De Michele, M. (2013). Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods. Journal of Geophysical Research: Solid Earth, 118(12), 6311-6327. 2169-9313 https://hdl.handle.net/10356/102071 http://hdl.handle.net/10220/18854 10.1002/2013JB010442 en Journal of geophysical research: solid earth © 2013 American Geophysical Union. This paper was published in Journal of Geophysical Research: Solid Earth and is made available as an electronic reprint (preprint) with permission of American Geophysical Union. The paper can be found at the following official DOI: [http://dx.doi.org/10.1002/2013JB010442]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. application/pdf |
| spellingShingle | DRNTU::Science::Physics::Meteorology and climatology Barbot, Sylvain Agram, Piyush De Michele, Marcello Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title | Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title_full | Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title_fullStr | Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title_full_unstemmed | Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title_short | Change of apparent segmentation of the San Andreas fault around Parkfield from space geodetic observations across multiple periods |
| title_sort | change of apparent segmentation of the san andreas fault around parkfield from space geodetic observations across multiple periods |
| topic | DRNTU::Science::Physics::Meteorology and climatology |
| url | https://hdl.handle.net/10356/102071 http://hdl.handle.net/10220/18854 |
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