On the Role of Temperature and Rheology in Seismicity in Convergent Margins

Ylona van Dinther, Luca Dal Zilio, Mario D'Aquisto, Robert Herrendörfer, & Taras Gerya

Published August 14, 2018, SCEC Contribution #8478, 2018 SCEC Annual Meeting Talk on Mon 11:00

Earthquake nucleation, propagation and arrest are governed by fault stress and strength. Thus understanding how these are regulated by long-term processes involving temperature, rheology and tectonic forcing - in combination with short-term earthquake interactions - is important. To decipher and extend our too limited and indirect observational record, we developed the first quantitative model able to simulate the dynamics governing both tectonic processes over millions of years and the family of fault slip processes down to milliseconds. We utilize this seismo-thermo-mechanical modeling framework to show how stress evolution, temperature, and crustal and lithospheric rheology interact to shape convergent margins, seismic cycle observations and seismicity behavior. Through quantifying their feedback in a self-consistent manner, we establish how convergence rate across continental collision zones affects temperature and viscosity distribution. This determines stress and strength distributions, which govern earthquake maximum magnitude, recurrence patterns, and Gutenberg-Richter statistics. In a more observationally constrained approach, temperature, geometry and forcing can be predefined using geological and geophysical constraints to improve our understanding of seismicity in particular regions. Such tectonically realistic models of the Nepal Himalaya demonstrate the Main Himalayan Thrust geometry facilitates a bi-modal seismicity regime with M>=8 surface ruptures following a series of deeper, ~M7 megathrust earthquakes. In the Northern Apennines (Italy), such models show that slab delamination and retreat along with a high temperatures and a ductile lower crustal rheology are necessary to match both long- and short-term observations. These self-consistent and regionally-constrained examples illustrate the importance of thermal and rheological models for understanding seismicity.

Key Words
tectonics, earthquake physics, fault mechanics, temperature, rheology, thermo-mechanical model

Citation
van Dinther, Y., Dal Zilio, L., D'Aquisto, M., Herrendörfer, R., & Gerya, T. (2018, 08). On the Role of Temperature and Rheology in Seismicity in Convergent Margins. Oral Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
SCEC Community Models (CXM)