GEOMETRIC MODEL OF THE NAZCA PLATE SUBDUCTION IN SOUTHWEST COLOMBIA
A geometric model for the subduction of the Nazca plate beneath the South American plate in southwestern of Colombia is proposed based on the relocation of hypocenters of local and distant<br />earthquakes. By means of the simultaneous inversion of teleseismic P and SH body waves, the...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Universidad Nacional de Colombia
2007-12-01
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| Series: | Earth Sciences Research Journal |
| Online Access: | http://www.revistas.unal.edu.co/index.php/esrj/article/view/21202 |
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| Summary: | A geometric model for the subduction of the Nazca plate beneath the South American plate in southwestern of Colombia is proposed based on the relocation of hypocenters of local and distant<br />earthquakes. By means of the simultaneous inversion of teleseismic P and SH body waves, the depths of the 15 events with Mw ≥ 5.8 were constrained, and the hypocenters of the 250 earthquakes recorded<br />between 1990 and 2005 by the International Seismological Centre (ISC) and U.S. Geological Survey, National Earthquake Information Center (NEIC) were constrained and relocated. A model is proposed<br />for the hypocentral sections taking into account the trench along of the Earth and Colombia-Ecuador.<br />Three different possible shapes of subduction of the Nazca plate in the Colombia-Ecuador trench were obtained: The first configuration, in the Cali A segment, the dip angle changes from17º to 45º down to a maximum depth of 100km; the second configuration, in the Popayán B and Nariño C segments, the dip angle holds approximately constant at 30º down to a maximum depth of 200 km; and the third configuration, in the Quito D segment, the dip angle changes of 9º to 50º to a maximum depth 220 km. The maximum depth of seismicity along the Colombia-Ecuador trench shows two increases, the first between latitudes 4.5ºN-5ºN and the second between the latitudes 1ºS-2ºS, which suggest that the presence of the Malpelo and Carnegie Ridges may generate a differential blockage at the Pacific Colombia-Ecuador basin. |
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| ISSN: | 1794-6190 |