Earthquake Triggering and Synchronization on Oceanic Transform Faults

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Strike-slip faults can cause major damage when they rupture near population centers. While the basic mechanism of slip along a single fault strand is relatively well understood, behavior of multi-strand faults within a historically active zone can be complex. Progress towards a quantitative and predictive understanding of fault behavior can be achieved by studying two types of fault system activity: 1) earthquake triggering- a distant earthquake triggers slip on a local fault; 2) earthquake synchronization- two large earthquakes occur close in time and space over many earthquake cycles on a given fault zone. Oceanic transform faults are ideal for studying such behavior because of their simple tectonic setting and relatively short earthquake cycle. This research helps establish a young researcher in a new university position, allowing him to extend his expertise to submarine faults, and it provides training for an undergraduate student.Investigation of earthquake triggering at oceanic transform faults takes advantage of the short cycle of loading and rupture (~20 yrs) for these systems. Coverage is sparse but a combination of ocean bottom seismographs, hydrophones, buoys, and near-shore land seismic stations do provide data. Earthquake catalogs will be searched for events that correspond with passage of waves from large teleseismic earthquakes or that indicate synchronous regional activity, suggesting events that are dynamically triggered by stress transfer between fault segments. In an effort to advance knowledge from conceptual to quantitative models, numerical modeling that incorporates rate and state friction parameters will be performed. A new development will be to include along-fault variations in 2-D models of fault properties and evolution. Fairly detailed data from the Blanco, Quebrada-Discovery-Gofar, Romanche and Eltanin fault systems will be employed, in contrast to previous work that depended on sparse teleseismic data for global studies of oceanic transform fault behavior.