A Geoelectrical Model of the Northern Flank of the Popocatepetl Volcano (Central Mexico): A First Approach to Major Structures

English Abstract:

Popocatepetl volcano is an active stratovolcano located in the central portion of the Trans-mexican Volcanic Belt, approximately 60 km east of Mexico City, the largest city in the country with over 22 million inhabitants. In December 1994 it resumed its eruptive activity and since then many studies have been carried out in order to understand the eruptive behavior and to assess the volcanic hazard. Nevertheless, no study has been conducted in order to image the distribution of electrical resistivity below the volcano. Thus, this study contributes in expanding the knowledge of the structures of the volcano and their relation to the eruptive activity. Since 1994, eruptive events and seismic monitoring have been improved and it is known that most of the activity is concentrated underneath the southeastern flank and below the crater. However, the largest volcanotectonic event (Mc 4.1) on May 6, 2013 was detected beneath the northern flank. For this reason, we decided to perform a magnetotelluric survey on the northern area with the main goal of spotting the characteristic structures and their relationship to the recent activity. The inversion geoelectrical models show the resistivity distribution below the northern flank and were generated from eight magnetotelluric surveys acquired during May 2014. The results show the existence of a body of high resistivity, on the eastern side of the prospected area, which correspond with the position of the Tlamacas dome. Also, the eastern limit of this resistive anomaly coincides with the location of the hypocenter of the earthquake on May 6, 2013, and probably depicts the presence of a NE-SW fault.