ARTÍCULO
Large scale landslides triggered by Quaternary tectonics in the Acambay graben, Mexico
G. Norini,
L. Capra,
L. Borselli,
F. R. Zuniga,
L. Solari
and D. Sarocchi
Earth Surf. Process. Landforms , 2010.
ABSTRACT:
Detailed analysis was conducted on large-scale gravitational-tectonic deformations and landslides in the Acambay graben, an intra-arc basin in the trans-Mexican volcanic belt (TMVB). Field mapping and remote sensing revealed the slope instability of the northern graben boundary induced by the Acambay-Tixmadejé fault. Two major landslides of 0·1 km3 and 0·05 km3 in volume were identifi ed and their characteristics were analyzed according to the role of tectonics, mechanism of slope failure, and possible triggering factors. Quaternary faulting played a major role in increasing the local relief, and the activity of the Acambay-Tixmadejé fault represents the main geomorphic factor conditioning the gravitational movements. Moreover, dis- placements along this fault generated sliding surfaces and reduced the strength of the rock mass. The two landslides are classifi ed as large-scale rotational slides involving volcanic rocks of late Miocene-Pleistocene age. Since the Acambay graben is a seismo- genic area with a known maximum horizontal ground acceleration of 0·5 g, a strong earthquake could be ascribed as the possible triggering mechanism of the landslides. Our work represents the fi rst analysis of large gravitational slope movements in tectoni- cally active regions in Mexico, a process that can be common in the intra-arc basins of the TMVB, where active tectonic, seismic- ity, weak altered volcanic rocks, and heavy rains affect the slope stability. Copyright © 2010 John Wiley & Sons, Ltd.