85th Sogo Bosai seminar

We are pleased to announce the 85th Sogo Bosai Seminar (Jan, 11 Thursday) as follows.
We look forward to your participation. This seminar will be held in English.
 
[Date & Time]
Jan. 11, Thursday, 15:00-17:00
 
[Venue *hybrid]
S519D of Main building, Uji campus and Online
If you will attend via online, please register yourself by noon, 10th Jan: https://forms.gle/r5nKiPyCD6RnDzsH7
 

-First presentation-
 

[Title]
Underlying Physics of the Tectonic Kinematics in Mexico
 

[Presenter]
Josué Tago Pacheco, Associate Professor, School of Engineering, National Autnomous University of Mexico (UNAM)

 
[Abstract]

In the latest SATREPS project with Mexico, 2016-2022, an amphibious seismo-geodetic network was deployed in the Guerrero seismic gap. This network allowed us to obtain data near the subduction interface, as never done before. This was the motivation to develop an inversion strategy, called ELADIN, to follow the tectonic kinematics in Mexico. With ELADIN, we have been able to follow the seismic coupling and the interaction between slow slip events and earthquakes. The next step is to understand the underlying physics of the complex tectonic kinematics. For this, we have implemented rate and friction laws in a 2D and 3D discontinuous Galerkin method. For the new SATREPS project, we want to infer friction parameters and initial stress conditions using tectonic kinematics inversions as constraints. These dynamic inversions will allow us to propose more realistic seismic scenarios and will constitute the first step for seismic cycle simulations.

 
[Short bio]
PhD. Josué Tago Pacheco is a Chemical Engineer graduated from the Celaya Institute of Technology. He later studied a Master’s degree in Computer Science and Industrial Mathematics at the Center for Research in Mathematics and a PhD in Earth Sciences at the Institute of Geophysics of UNAM. He then did a postdoctoral stay at the Institute of Earth Sciences of the Joseph Fourier University, France. After finishing, he joined the Geophysics Department of the School of Engineering at UNAM as a full time professor. His research focuses on mathematical and computational modeling of geophysical systems. In 2021 he received the recognition “National University Distinction for Young Academics” in the area of teaching in exact sciences. From 2024 to 2029 he will be responsible for the Mexican team of the tri-national SATREPS project, with Japan and El Salvador, “The Project for Compound Disaster Risk Reduction associated with Large Earthquakes and Tsunamis”.
 

-Second presentation-
 

[Title]
Strong Ground Motion Variation due to Local Complex Geology During the Earthquake of September 19, 2017 (Mw 7.1)
 

[Presenter]
Martín Cárdenas-Soto, Professor, School of Engineering, National Autnomous University of Mexico (UNAM)
[Abstract]
September 19, 2017, earthquake considerably affected buildings, neighborhoods, and even plumbing lines buried in the geotechnical transition zone of Mexico City. This zone is associated with a high geological hazard due to faults, cracks, subsidence, landslides, and sinkhole collapses. The lesson learned from this earthquake showed that much remains to be known, and detailed subsoil characterization is needed to define vulnerable sites that allow for the reduction of seismic-geological risk. We conduct seismic noise records (30 min) along lines with 48-4.5 Hz vertical geophones and Resistive Electric Tomography (ERT) lines. In addition, we have acquired ambient vibration measurements to estimate the site effects. The objective is to explore the subsoil structure under a housing unit in a transition zone south of Mexico City to understand the destructively strong ground motion produced by complex geology. The results show that the subsoil properties vary drastically in lateral and in-depth directions. In particular, it highlights the presence of a discontinuity that divides the area into two different structures. The observed damages are due to dynamic amplification effects associated with the structure’s irregularity.
 

[Short bio]
I am a Geophysical Engineer with postgraduate studies in Seismology and Physics of the Earth’s Interior at Universidad Nacional Autónoma de México (UNAM). I am currently a full-time professor at the School of Engineering, where I teach subjects related to seismic methods. I also participate as a professor and tutor of the Postgraduate Courses in Engineering and Earth Sciences of the UNAM. My line of research began studying the seismic response of central Mexico, where I also dabbled in seismic engineering with topics of the seismic response of soft soils and the vibration of buildings. I currently develop and apply seismic refraction and ambient seismic noise techniques for geotechnical purposes, landslide, forensic exploration, and archaeology. I have been the Coordinator and Head of the Department of Bachelor Geophysical program and coordinated the Academic Subcommittee of the Postgraduate in Exploration and Exploitation of Natural Resources. I am currently a full-time professor, Titular C, at the Faculty of Engineering, UNAM.
 

-Third presentation-
 

[Title]
Susceptibility models to multiple debris flows triggered by extreme rainfall, applications in El Salvador, Central America
 

[Presenter]
Miguel Ángel Hernández Martínez, Professor, Faculty of Agricultural Science, University of El Salvador
[Abstract]
The susceptibility to landslides triggered by extreme rains was evaluated with emphasis on DT96E/hurricane IDA 2009, which caused landslides in the Ilopango caldera. To analyze the statistical effect of the extreme event, it was compared with a landslide inventory of the same area from 2003 considered a normal year. The research was carried out in the Arenal de Cujuapa micro-basin, Ilopango caldera, with a predominance of San Salvador, Cuscatlán and Bálsamo Geological Formations, upper strata of Tierra Blanca Jóven. Multivariate Logistic Regression was used, the predictors were Lithology, land use, elevation, slope, orientation, curvature and topographic humidity index. Open Source tools were used: QGIS, ZAGAGIS and R-Studio, and MARS (Multivariate Adaptive Regression Spline), using “EARTH” from “R”. Google Earth satellite images from 2003 and 2009 were used to obtain an inventory of 1503 (2003) and 2237 (2009) landslides respectively, constituting the calibration data set. The validation schemes were: Self-validation, based on random partition; Chrono-validation, based on temporal partitioning; Transfer model, based on spatial partitioning. Precision was evaluated using the values of Areas Under the Curve (Receiver Operating Characteristics and Confusion Matrices. The 2003 and 2009 Self-Validation models resulted with the highest performance values according to their AUC value>0.8. The Chronovalidated models presented good performance although with a decrease in its AUC value>0.77. The 2009 inventory was able to detect 80% of the landslides in 2003 and a high number of instabilities that were stable zones in 2003 (Type I error). The influence of predictive power is confirmed. of the models according to the data set and the triggering conditions. The 2003 landslide inventory made it possible to calibrate a high-performance predictive model referring to 2009 with a decrease in sensitivity to identify the instabilities that occurred in 2009.
 

[Short bio]
Graduated Master’s Degree in Geology, University of El Salvador, Graduated Doctorate in Earth and Marine Sciences University of Palermo Italy 2017; Master’s Degree in Sustainable Agriculture, University of El Salvador 2010; Title of University Expert in Geographic Information Systems from the International University of Andalusia-Spain 2005; Diploma in Geographic Information Systems Applied to Sustainable Development UES-2007.