Structural configuration of the Teras fault (southern Basin and Range Province) and its rupture in the 3 May 1887 MW 7.5 Sonora, Mexico earthquake
During the great 3 May 1887 Sonoran earthquake (surface rupture end-to-end length: 101.8 km;MW = 7.5±0.3), an array of three north-south striking Basin and Range Province faults (from north tosouth Pitáycachi, Teras, and Otates) snapped along the western margin of the Sierra Madre Occidentalplateau....
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2008 |
| País: | México |
| Recursos: | Universidad Nacional Autónoma de México |
| Repositorio: | Redalyc-UNAM |
| OAI Identifier: | oai:redalyc.org:57225111 |
| Acesso em linha: | https://www.redalyc.org/articulo.oa?id=57225111 |
| Access Level: | acceso abierto |
| Palavra-chave: | Ciencias de la Tierra seismotectonics earthquake geology 1887 Sonoran earthquake earthquake surface rupture Southern Basin and Range Province |
| Resumo: | During the great 3 May 1887 Sonoran earthquake (surface rupture end-to-end length: 101.8 km;MW = 7.5±0.3), an array of three north-south striking Basin and Range Province faults (from north tosouth Pitáycachi, Teras, and Otates) snapped along the western margin of the Sierra Madre Occidentalplateau. My detailed field survey of the Teras fault and the 1887 earthquake rupture zone along this faultincluded mapping the rupture scarp and measuring surface deformation at 27 sites.The Teras fault is ~20 km long, strikes N12°E, and has an average dip of 62°W; its maximum throwis >1,640 m and its long-term slip rate >0.08 mm/yr. The fault is structurally simple; it is not internallysegmented along strike and does not branch. Striation measurements and the style of faulting indicateextensional dip-slip without significant lateral displacement. In the north, a 2.5-km wide, unbreachedright step-over separates the Pitáycachi and Teras faults, whereas the southern limit of the Teras faultis a partly breached relay ramp, where the fault trace shows a 60° bend and jogs to the west. Here, thedisplacement of the Teras fault is transferred onto the Otates fault and the normal faults bounding theIglesitas horst.The 1887 surface rupture along the Teras fault (end-to-end length 19.9 km) generally coincides withthe mapped trace of the Teras Basin and Range Province fault. Based on 27 measurements, the maximumsurface offset is 184 cm and the mean offset 112 cm. The along-rupture surface offset distribution isasymmetric, with the maximum near the southern end of the segment. This suggests that the Teras andOtates segments could be part of a single continuous 1887 rupture that stepped across the structurallycomplex basement ridge between them. A rough estimate of the average recurrence interval of 1887-sizeearthquakes on the Teras fault can be obtained from the average slip rate since 23 Ma and the amountof slip on this segment during the 1887 earthquake; the resulting values are 15 to 26 kyr |
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