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Implications Of a Newly Discovered Active Fault In The Basin Of Mexico

Simpson, K (2021) Implications Of a Newly Discovered Active Fault In The Basin Of Mexico. Masters thesis, Liverpool John Moores University.

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Abstract

Seismic-source detection of local earthquakes inside the Basin of Mexico has recently become more precise and the inferred faults and fractures from which the seismic events originate are well documented. Mooser (2018) provided a new theory on faulting which revisits the evolution of the Basin as a high-altitude volcano-tectonic depression. Using stereographic modelling, a series of shallow inferred faults have been identified, which strike along the elliptical orientation of the basements high-altitude volcanic axis. Following Mooser’s (2018) 2D stereographic model illustrating the eastern region of the Trans-Mexican Volcanic Belt (TMVB), this study attempts to quantify the existence of a shallow crustal fault, a new type of fault with formation processes attributed to the unique geological conditions in the Basin of Mexico and evaluate the effects of a projected fault displacement on the population and infrastructure of the neighbouring municipalities. Probabilistic and deterministic methodologies were used to complete a geophysical survey in the western region of the basement, and calculate the fault schematics, while visual observations of structural damage in Mexico City from the M_w7.1 19/09/2017 Puebla/Morelos earthquake were used as a proxy for understanding the building performance and demographic risk of a fault displacement within the Basin of Mexico. The results of this study substantiate the possible existence of an active 23.5km shallow crustal fault in an area of critical stress between Xitle volcano and Iztacalco in the Basin of Mexico. It is likely that Structurally Controlled Differential Subsidence (SCDS) associated with the rapid 20th century increase in anthropogenic activity in Mexico City, and strong-ground motion from major national earthquakes, has accelerated a subsurface fracture formation sequence by exceeding the basements maximum stress capacity. The projected maximum M_s 6.7 output from a full-length rupture of the shallow crustal fault originating from within the Basin, forecasts a potential scenario that is likely to have more severe socio-economic implications to those experienced during the 2017 M_w 7.1 Puebla-Morelos earthquake, with insufficient ground-motion warning time from the Seismic Alert System for the population in Mexico City and its neighbouring municipalities.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Seismology; Mexico; Geoscience; Basin; Fault; Mooser
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Biological & Environmental Sciences (new Sep 19)
Date Deposited: 12 Oct 2021 10:47
Last Modified: 12 Oct 2021 10:48
DOI or Identification number: 10.24377/LJMU.t.00015628
Supervisors: Gonzalez, S
URI: https://researchonline.ljmu.ac.uk/id/eprint/15628

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