Faculty candidate seminar - Ross Parnell-Turner

04/10/2017 - 4:00pm


DATE:          April 10th, Monday, 4 p.m.  

LOCATION:     Hubbs Hall 4500
SPEAKER:      Ross Parnell-Turner, Ph.D.
TITLE:          Plate Bending and Compression on Detachment Faults at the Mid-Atlantic Ridge

The formation of new oceanic crust by slip on low-angle faults, known as detachments, is responsible for vast areas of seafloor.  However, the mechanics and subsurface geometry of this process remain largely unknown. An effective way to tackle these shortcomings is by analysis of naturally occurring seismicity generated as deformation takes place in the detachment fault system.  Although several previous local seismicity surveys have been conducted at oceanic detachments, none of them have had sufficient aperture to quantify modes of deformation. Here I will present data from a dense network of 25 short-period ocean bottom seismographs, which was deployed for six-months on the Mid-Atlantic Ridge near 13°N.  More than 244,000 microearthquakes were detected over 6 months, indicating a remarkably high seismicity rate.  Surprisingly, the majority of these were reverse faulting events. These data indicate that the lower portion of the detachment footwall experiences compression, leading to internal deformation as the fault rolls over to low angles, before emerging at the seafloor.  I will discuss the consequences of this result for the rheology of these low-angle fault systems, and the implications for how oceanic crust is accreted under low magma supply conditions.
Faculty Host:  Neal Driscoll  (ndriscoll@ucsd.edu)
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Hubbs Hall 4500