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Finding Fault With Earthquakes

Description: 

The 2019-2020 seismic sequence brought into to focus the disjunction between geophysical and geological investigations and detailing and recognizing local seismic hazards. Geophysical data and events are real time gathered over 10s of years, geomorphic-tectonic features are near term formed over a few million years or less, whereas geologic structures may have formed even over 10s millions of years. Detailing the seismic hazard requires data on the slip rates of active faults which proved elusive for the Punta Montalva Fault because of climate and low slip rates. Larger scale geomorphic features while useful for recognizing neotectonic activity require time to develop especially where displacement rates are low. The ongoing Guanica-Guayanilla seismic sequence of 2019-20 has provided us with a great opportunity to recognize active fault zones by tracking earthquakes and relating them to faults exposed at the surface. In some cases these seismic fault zones are only recognizable at the surface by faults with orientations that differ significantly with earthquake mechanisms but are still consistent with the overall stress orientations. Not only is the association of earthquakes with surface faults important for scientific investigation it is essential for public communication about earthquake activity. Faults are something real and even visible that the public can relate to and allow us to explain why the earthquakes are occurring. They give us context within a regional tectonic framework about how pieces of our island are moving and why. The Punta Montalva Fault provided that context and something the press and public could relate to.

Session: The 2020-2021 Southwest Puerto Rico Seismic Sequence: Current State of Knowledge and Implications

Type: Oral

Date: 4/18/2023

Presentation Time: 08:30 AM (local time)

Presenting Author: James Joyce

Student Presenter: No

Invited Presentation: Yes

Authors