SCEC Award Number 20172 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Coseismic Chemistry: Developing kinetics of various chemical reactions over earthquake timescales
Name Organization
Heather Savage University of California, Santa Cruz Pratigya Polissar University of California, Santa Cruz
Other Participants
SCEC Priorities 3d, 3f, 2d SCEC Groups FARM, Geology, Seismology
Report Due Date 03/15/2021 Date Report Submitted 05/06/2021
Project Abstract
The mechanical strength and behavior of faults is in part controlled by chemical reactions. However, the chemistry of fault zones during earthquakes is not well understood because many of the important reactions have generally been studied at equilibrium conditions, whereas pressures and temperatures change dramatically over very short times (seconds) during earthquakes. Thus we need to understand the rates of chemical reactions at high temperatures and short timescales in order to calibrate paleoseismic indicators and explore mechanical feedbacks between frictional strength and temperature. We perform short duration experiments with accurate and repeatable temperatures to determine reaction kinetics relevant to earthquake heating. Ultimately, these kinetic parameters will be used to model and understand how the time-varying temperatures during earthquake heating produce the measured chemical signatures in exhumed or drilled faults. Specifically for this project, we focused on the kinetics of biomarker thermal maturity and carbonate dissociation.
Intellectual Merit Localized temperatures generated from frictional heating during earthquakes disrupts the chemical equilibrium in the fault zone. Such disequilibrium can leave chemical signatures of earthquakes in the rock record that help us map fundamental aspects rupture mechanics such as slip localization and propagation. Furthermore, accurate estimates of earthquake temperatures allow us to explore chemo-mechanical feedbacks that impact processes such as dynamic weakening and post-seismic restrengthening.
Broader Impacts This grant has supported UCSC grad student Julia Krogh. Studies of fault zone temperature rise during earthquakes has led to better understanding of what controls earthquake propagation and arrest.
Exemplary Figure Figure 1. Schematic of rapid heating apparatus.