Velocity-weakening behavior of Westerly granite at temperature up to 600 degrees C

TitleVelocity-weakening behavior of Westerly granite at temperature up to 600 degrees C
Publication TypeJournal Article
Year of Publication2016
AuthorsMitchell EK, Fialko Y, Brown KM
JournalJournal of Geophysical Research-Solid Earth
Volume121
Pagination6932-6946
Date Published2016/09
Type of ArticleArticle
ISBN Number2169-9313
Accession NumberWOS:000385845700037
Keywordscalifornia; earthquake instability; experiments; friction; granite; hydrothermal conditions; lower crust; rock friction; san-andreas fault; seismicity; Shear; slip; state-dependent friction; stick-slip; temperature; united-states; unstable
Abstract

The deep limit to seismicity in continental crust is believed to be controlled by a transition from velocity-weakening to velocity-strengthening friction based on experimental measurements of the rate dependence of friction at different temperatures. Available experimental data on granite suggest a transition to stable creep at about 350 degrees C (approximate to 15km depth). Here we present results from unconfined experiments on Westerly granite at both dry and hydrated conditions that show increasingly unstable slip (velocity-weakening behavior) at temperature up to 600 degrees C. A comparison of previously published experimental results with those presented in this study suggests that the rate and state friction parameters strongly depend on normal stress and pore pressure at high (>400 degrees C) temperature, which may help explain regional variations in the depth distribution of earthquakes in continental crust. Temperature dependence of the rate and state friction parameters may also contribute to strong dynamic weakening observed in high-speed friction experiments on crystalline rocks such as granite and gabbro.

DOI10.1002/2016jb013081
Student Publication: 
No
sharknado