Forearc density structure of the overriding plate in the northern area of the giant 1960 Valdivia earthquake
<p>The objective of this work is to analyse the density structure of the continental forearc in the northern segment of the 1960 <span class="inline-formula"><i>M</i><sub>w</sub></span> 9.6 Valdivia earthquake. Regional 2D and local 3D density mode...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-01-01
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| Series: | Solid Earth |
| Online Access: | https://se.copernicus.org/articles/13/117/2022/se-13-117-2022.pdf |
| Summary: | <p>The objective of this work is to analyse the density
structure of the continental forearc in the northern segment of the 1960 <span class="inline-formula"><i>M</i><sub>w</sub></span> 9.6 Valdivia earthquake. Regional 2D and local 3D density models have been
obtained from available gravity data in the area, complemented by new
gravimetric stations. Models are constrained by independent
geophysical and geological information and new TEM and MT soundings. The results
show a segmentation of the continental wedge along and perpendicular to the
margin, highlighting a high-density anomaly, below the onshore forearc
basin, that limits the late Paleozoic–early Mesozoic metamorphic basement in
the region where Chaitenia terrane has been proposed. A progressive landward
shift of this anomaly correlates with the high slip patch of the giant 1960
<span class="inline-formula"><i>M</i><sub>w</sub></span> 9.6 Valdivia earthquake. Based on these results, we propose that the
horizontal extension of the less rigid basement units conforming the marine
wedge and Coastal Cordillera domain could modify the process of stress
loading during the interseismic periods, and also that changes in position
and extension of the late Paleozoic–early Mesozoic accretionary complex
could be linked with the frictional properties of the interplate boundary.
This analysis provides new evidence of the role of the overriding plate
structure in the seismotectonic process in subduction zones.</p> |
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| ISSN: | 1869-9510 1869-9529 |