Speaker
Prof.
Víctor Hugo GARDUÑO-MONROY
(INICIT-UMSNH)
Description
The Oaxaca valley was one of the sites with more development in prehispanic cultures, highlighting Monte Alban that has been the most important site of the Zapotec culture. However, this great advance in Mesoamerica, the geological scenario makes the Oaxaca state is vulnerable with seismic activity, as the recent earthquakes of 2017 (Mw8.2) and 2018 (Mw7.2) showed. In the past, different events have been reported, standing out those of 1899 (M8.4) 1903 (M8.2) and 1928 (8.0). This activity is the product of the subduction of the Cocos Plate under the North American plate, inside this last one there are great faults associated with the central valleys of Oaxaca, where the Zapotec and part of the Mixtec cultures were established with the constructions of Monte Alban (500 BC-750 AD) and Mitla (950 AD to 1521 AD).
Geologically the prehispanic population of Mitla is located in a NW-SE normal fault valley with slight left components and that to the north constitute the regional structure called Oaxaca-Tehuacán fault. These structures displace the Precambrian and Paleozoic rocks of the Oaxaca and Zapoteco terrains, sometimes covered with Mesozoic sedimentary rocks or, as in the case of Mitla, covered by large packages of Miocene pyroclastic products (ignimbrite,14Ma).
Morphologically, the normal NW-SE fault that generates the Mitla valleys stands out and, together with the seismic activity, generated two major collapses that former spectacular avalanche deposits. In this work we will present the Mitla avalanche, that having been generated by an earthquake at a time not yet established but that could be related to a possible great disaster in the prehispanic population of Mitla, (Mitla means “place of dead” or “large burials”). With the avalanche data we can establish that the ratio of H / L is 0.547, its area of 19,132 m2 and its volume of 0.546km3.
Primary author
Prof.
Víctor Hugo GARDUÑO-MONROY
(INICIT-UMSNH)
