Crustal Seismic Discontinuities Under Mexico City Observed With Receiver Functions

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Mexico City is the seat of the Mexican government and the most populated city of the country. It was settled on top of a sedimentary basin which cause amplification to seismic waves of large subduction earthquakes occurring at the Pacific Coast, more than 350 km away, as well as for near intraplate earthquakes, such as the 19 September 2017, Mw7.1, Puebla-Morelos earthquake.

With the purpose of improving our knowledge of the seismic structure of the city and reducing the uncertainty when modeling strong motion in the basin, an ambitious experiment started in May 2017. This experiment consists in installing from 18-22 broadband stations for 3 to 5 days in a site to continuously record; the stations are then relocated to a new site for a similar period, integrating a dense grid of measuring points with ~500 m spacing. Additionally, 18 stations which have been recording continuously since 2010, from the ‘Red Sísmica del Valle de México’(RSVM) are available. We also use data from nine stations of the MesoAmerican Subduction Experiment, a previous array that crossed Mexico City from south to north between 2014 and 2015; and a permanent broadband station of Servicio Sismológico Nacional (SSN, National Seismological Service, Mexico)

In this work, we obtain receiver functions, from both the temporal and permanent RSVM and SSN stations. Despite the small number of teleseisms registered in the temporary array, but given the small distance between stations, it is possible to identify the Ps converted waves from the Mohörovic discontinuity, as well as from other shallower crustal discontinuities. Furthermore, it is possible to differentiate the receiver functions that have gone through shallow low-velocity layers from the ones that have not, being able to identify the presence of the lake sediments. This project has been funded by Secretaría de Ciencia y Tecnología e Innovación (SECITI), project SECITI/073/2016.

Presenting Author: Olivia D. Pita-Sllim

Authors