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| Titel |
Revisiting the North Chile seismic gap segmentation using GPS-derived interseismic coupling |
| VerfasserIn |
Marianne Metois, Anne Socquet, Christophe Vigny, Daniel Carrizo, Peyrat Sophie |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074916
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| Zusammenfassung |
| The North Chile area did not rupture since the 1877 Mw 8.6 earthquake that produced a huge
tsunami. Considering that upper plate deformation measured there by modern geodetic tools
is due to some degree of locking on the subduction interface and the long elapsed
time since 1877, many consider this area is a mature seismic gap where seismic
hazard is high. We present a new GPS velocity field that describes in some detail the
interseismic deformation between 18°S and 24°S. We invert for coupling distribution on
the subduction interface using elastic modeling. Our measurements require that,
at these latitudes, 10 to 12 mm/yr (i.e ~15% of the whole convergence rate) are
taken up by the clockwise rigid rotation of an Andean block bounded to the East
by the subandean fold-and-thrust belt. This reduces the accumulation rate on the
subduction interface to ~56 mm/yr in this area. We describe coupling variations on the
subduction interface both along-strike and along-dip. We find that this gap is segmented
in at least two highly locked segments and two narrow low coupled intersegment
zones (Iquique and Mejillones areas). This coupling segmentation is consistent
with our knowledge of the historical ruptures and of the instrumental seismicity of
the region. Intersegments correlate with high background seismic rate and local
tectonic complexities on the upper or downgoing plates. The rupture of either the
Paranal or the Loa segment alone could easily produce a Mw 8.0-8.3 rupture, and we
propose that the Loa segment (from 22.5°S to 20.8°S) may be the one that ruptured in
1877. |
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