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Challenges in Hazard and Risk Assessment for Seismicity in Volcanic Regions: Cases for Guadeloupe and Italy

Description: 

We all know that volcanoes and seismicity are correlated. Yet, in traditional Probabilistic Seismic Hazard Analysis (PSHA), seismicity in volcanic regions is often not considered, grouped into the regional background model despite clear tectonic differences, or considered at a very simplified level. Assessing the seismic hazard and risk in these tectonically-complex regions certainly has its challenges that we don’t pretend to have the answers for; rather, we take a dive into the most impactful aspects of modeling seismicity in volcanic regions: rate modeling, maximum magnitude, scaling relations.

In this study, we highlight examples from Guadeloupe and Italy to explore key issues and pose several questions to the community on how to model such seismicity. (1) How does volcanism impact the maximum magnitude? Volcanoes and associated high heat flow can act as barriers to rupture propagation on crustal faults as well as change the recurrence characteristics of nearby faults. (2) How do we build a recurrence model for a non-stationary process? The variable stressing/loading rates and non-constant material properties in a volcanic region mean the classical approaches of Gutenberg and Richter (1944) and/or Poisson modeling may not be appropriate. The task of balancing the swarm-like behavior of volcanic seismicity with the threat of flank-collapse seismicity is also a challenge. (3) How do simplified approximations of modeling this seismicity compare to more detailed approaches? Is it sufficient to only consider a different scaling relation and ground motion model? Or is modifying the rate model alone sufficient? Can we get “close enough” by only changing one or two aspects of a model, or do we truly need more detailed models for volcanic regions?

We consider these issues and give examples in Guadeloupe and Italy where we have observed variations in the hazard and risk, depending on how this seismicity is handled.

Session: Improving the State of the Art of Earthquake Forecasting Through Models, Testing and Communication - I

Type: Oral

Date: 4/15/2025

Presentation Time: 03:00 PM (local time)

Presenting Author: Jessica

Student Presenter: No

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