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On the similarity between pre-seismic locking and coseismic slip during the 2010 Maule earthquake

Urheber*innen
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Moreno,  M.
3.1 Lithosphere Dynamics, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

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Rosenau,  M.
3.1 Lithosphere Dynamics, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

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Melnick,  Daniel
3.1 Lithosphere Dynamics, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

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Oncken,  O.
3.1 Lithosphere Dynamics, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

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Keiding,  Marie
2.6 Seismic Hazard and Stress Field, 2.0 Physics of the Earth, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Baez,  J.C.
External Organizations;

Bevis,  M.G.
External Organizations;

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Chen,  Junping
1.1 GPS/GALILEO Earth Observation, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Tassara,  A.
External Organizations;

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Motagh,  M.
1.4 Remote Sensing, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Socquet,  A.
External Organizations;

Cisternas,  M.
External Organizations;

Bataille,  K.
External Organizations;

Hase,  H.
External Organizations;

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Zitation

Moreno, M., Rosenau, M., Melnick, D., Oncken, O., Keiding, M., Baez, J., Bevis, M., Chen, J., Tassara, A., Motagh, M., Socquet, A., Cisternas, M., Bataille, K., Hase, H. (2010): On the similarity between pre-seismic locking and coseismic slip during the 2010 Maule earthquake - Abstracts, AGU 2010 Fall Meeting (San Francisco, USA 2010), G32A-03.


Zitierlink: https://gfzpublic.gfz-potsdam.de/pubman/item/item_828893
Zusammenfassung
The M8.8 Maule earthquake of 27 Feb. 2010 in Chile was the largest earthquake that ruptured a mature seismic gap in a subduction zone, monitored with a dense space-geodetic network. This provides an image of the pre-seismically locked state of the plate interface of unprecedented high resolution, allowing for an assessment of the spatial correlation of interseismic locking and coseismic slip. Here we use GPS observations spanning the decade preceding the 2010 Maule earthquake to derive the pre-seismically surface deformation. Additionally, we use static coseismic surface displacements of 42 campaign GPS sites, InSAR data and land level changes to constrain the co-seismic slip distribution. Inter- and coseismic surface velocities are modeled using a spherical and layered finite element model (FEM) of the Andean subduction zone, including topography, bathymetry and realistic plate configurations as compiled from recent geophysical transects. According to our analysis, the 2010 Maule earthquake ruptured a part of the plate margin that was accumulating stresses across a heterogeneously locked interface in the final few years of an earthquake cycle. Despite differences in resolution and complexity, our and published slip distributions show a first-order pattern of two high-slip patches (asperities) north and south of the epicenter and separated by a low-slip zone 50-100 km wide. The rupture stopped in areas that were highly locked before the earthquake but where pre-stress had been significantly reduced by overlapping twentieth-century earthquakes. The largest recorded coastal uplift of up to 2 m occurred in the Arauco Peninsula, with peak horizontal displacements of 5 m at the Santa María Island. In the preliminary slip model presented we relate this uplift to elastic deformation caused by an asperity with slip of up to ~8 m in the southernmost part of the rupture. This slip component has not been seen by teleseismic models published so far presumably because of the network configuration, low slip velocities, simplified fault geometry, or bilateral propagation of the rupture. Inspection of the similarity between coseismic slip distributions and the pre-seismic locking reveals a high degree of coherence: The two asperities which ruptured in 2010 appeared to have been nearly fully locked before the earthquake. Between these asperities, the rupture bridged the zone that was not fully locked with consistent low coseismic slip. Based on the delicate balance between the 2010 coseismic slip and theoretically accumulated slip deficit since 1835 (which can be calculated under the assumption that the pre-seismic locking pattern is representative of the entire interseismic period) it appears that the observed locking pattern has been temporally largely invariant over the seismic cycle. Our observation suggests that coseismic slip heterogeneity at the scale of single asperities, and therefore the seismic potential of future great earthquakes, can be anticipated by foregoing geodetic observations.