Earthquake behavior and structure of oceanic transform faults
Roland, Emily C.
MetadataShow full item record
LocationEast Pacific Rise
Oceanic transform faults that accommodate strain at mid-ocean ridge offsets represent a unique environment for studying fault mechanics. Here, I use seismic observations and models to explore how fault structure affects mechanisms of slip at oceanic transforms. Using teleseismic data, I find that seismic swarms on East Pacific Rise (EPR) transforms exhibit characteristics consistent with the rupture propagation velocity of shallow aseismic creep transients. I also develop new thermal models for the ridge-transform fault environment to estimate the spatial distribution of earthquakes at transforms. Assuming a temperature-dependent rheology, thermal models indicated that a significant amount of slip within the predicted temperature-dependent seismogenic area occurs without producing large-magnitude earthquakes. Using a set of local seismic observations, I consider how along-fault variation in the mechanical behavior may be linked to material properties and fault structure. I use wide-angle refraction data from the Gofar and Quebrada faults on the equatorial EPR to determine the seismic velocity structure, and image wide low-velocity zones at both faults. Evidence for fractured fault zone rocks throughout the crust suggests that unique friction characteristics may influence earthquake behavior. Together, earthquake observations and fault structure provide new information about the controls on fault slip at oceanic transform faults.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2012
Showing items related by title, author, creator and subject.
Tectonics of the East Pacific rise : studies of faulting characteristics and magnetic and gravity anomalies Lee, Sang-Mook (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-02)The global mid-ocean ridge system is one of the most striking geological features on the surface of the Earth. In this system, the East Pacific Rise (EPR) is the fastest spreading ridge and is thus considered as the most ...
Boettcher, Margaret S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2005-06)The relatively simple tectonic environment of mid-ocean ridge transform fault (RTF) seismicity provides a unique opportunity for investigation of earthquake and faulting processes. We develop a scaling model that is ...
Trehu, Anne M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982-02)In this thesis, seismic waves generated by sources ranging from 2.7 kg shots of TNT to magnitude 5 earthquakes are studied in order to determine the seismic activity and crustal structure of the Orozco transform fault. ...