HR: 1340h
AN: T23B-1417    [Abstracts]
TI: Long-term Seismicity Comparisons from Oceanic Transforms Bounded by Slow, Intermediate, and Fast Mid-ocean Ridge Spreading Segments
AU: * Haxel, J H
EM: joe.haxel@noaa.gov
AF: Oregon State University/ NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Drive Hatfield Marine Science Center, Newport, OR 97365,
AU: Dziak, R P
EM: robert.p.dziak@noaa.gov
AF: Oregon State University/ NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Drive Hatfield Marine Science Center, Newport, OR 97365,
AU: Matsumoto, H
EM: haru.matsumoto@noaa.gov
AF: Oregon State University/ NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Drive Hatfield Marine Science Center, Newport, OR 97365,
AU: Fowler, M J
EM: matt.fowler@noaa.gov
AF: Oregon State University/ NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Drive Hatfield Marine Science Center, Newport, OR 97365,
AU: Lau, T K
EM: andy.lau@noaa.gov
AF: Oregon State University/ NOAA Pacific Marine Environmental Laboratory, 2115 SE OSU Drive Hatfield Marine Science Center, Newport, OR 97365,
AB: Long-term observations of seismicity along oceanic transform faults have traditionally been difficult due to limited coverage provided by land based seismic networks. More recently, hydroacoustically recorded earthquakes have been catalogued along the East Pacific Rise (EPR), Mid Atlantic Ridge (MAR), and in the northeast Pacific by the NOAA/PMEL and Oregon State University Acoustic Monitoring Program. These catalogs reduce earthquake detection thresholds by nearly 2 orders of magnitude for the slow spreading MAR, the intermediate spreading Juan de Fuca system, and the fast spreading EPR allowing for a more complete long-term time series of seismic activity along the associated transforms in each spreading regime. Using these hydroacoustically derived earthquake catalogs from 1996-2005, this study examines the long-term temporal and spatial seismicity rate patterns of oceanic transform faults bounded by slow, intermediate, and fast mid-ocean ridge spreading. Our analysis includes 5 MAR transforms, 1 northeast Pacific, and 7 EPR tranform faults. Using standard time series analysis techniques in addition to empirical orthogonal functions (EOF), we describe time space patterns along each transform, characterize seismic behavior between transforms within each spreading regime, and finally compare seismicity time series between transforms bounded by different spreading rates. Through our analysis we anticipate the development of an oceanic tranform fault index parameterized by background seismicity rate, seismicity rate variability during seismic events, fault length, degree of tranform segmentation, and rate of spreading along bounding ridge segments. Utilizing a more complete hydroacoustically derived earthquake catalog provides an unprecedented and comprehensive approach for examining long-term seismicity patterns in transform faulting within these 3 mid-ocean ridge settings.
DE: 3035 Midocean ridge processes
DE: 3039 Oceanic transform and fracture zone processes
DE: 7250 Transform faults
SC: Tectonophysics [T]
MN: 2007 Fall Meeting