Crustal structure of Oaxaca, Mexico, from seismic refraction measurements
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Abstract
Seismic refraction and gravity data have been analyzed to obtain a model of the compressional-wave velocity structure of the ocean-to-continent transition in the State of Oaxaca in southwestern Mexico. Crustal thickness on the continent at the latitude 18°N is 45 ± 4 km, based on reflected phases from the Moho discontinuity. The crust has been modeled with three layers, with velocities of 4.3 to 4.6, 5.0 to 5.7, and 6.85 to 7.0 km/sec, each with positive velocity gradient. The crust thins to 10 km at the coast near Pinotepa Nacional, where Precambrian metamorphic rocks are exposed 45 km from the mid-America trench. Offshore, the oceanic structure consists of an 8-km-thick crust with a normal crustal velocity structure (Spudich and Orcutt, 1980). The apparent dip of the subducting plate beneath western Mexico is 10°. On the oceanic side, strong reflections suggest a minimum depth of 35 km for the lithosphere-asthenosphere boundary. The asthenosphere has a seismic velocity of 7.6 km/sec, and a thin lid in which the velocity is 8.6 km/sec.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Crustal structure of Oaxaca, Mexico, from seismic refraction measurements |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/BSSA0760020547 |
| Volume | 76 |
| Issue | 2 |
| Year Published | 1986 |
| Language | English |
| Publisher | Seismological Society of America |
| Contributing office(s) | Earthquake Science Center |
| Description | 17 p. |
| First page | 547 |
| Last page | 563 |
| Country | Mexico |
| State | Oaxaca |
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