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Woods Hole Oceanographic Institution

Jeff J. McGuire

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Publications
»Gofar Transform Earthquakes
»

The Network Strain Filter - A New Tool for Monitoring and Detecting Transient Deformation Signals in GPS Arrays


»

Scaling Relations for Seismic Cycles on Mid-Ocean Ridge Transform Faults


»Earthquake Swarms on Transform Faults
»Modeling Seismic Swarms Triggered by Aseismic Transients
»Analysis of Seafloor Seismograms of the 2003 Tokachi­Oki
  Earthquake Sequence for Earthquake Early Warning


»Seismic Cycles
»Fore-arc structure and subduction zone earthquakes
»Salton Trough Swarms
»Earthquake Predictability
»SEAJADE Experiment


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A. L. Llenos and J. J. McGuire, Influence of fore-arc structure on the extent of great subduction zone earthquakes, J. Geophys. Res, 2007

Structural features associated with fore-arc basins appear to strongly influence the rupture processes of large subduction zone earthquakes. Recent studies demonstrated that a significant percentage of the global seismic moment release on subduction zone thrust faults is concentrated beneath the gravity lows resulting from fore-arc basins. To better determine the nature of this correlation and to examine its effect on rupture directivity and termination, we estimated the rupture areas of a set of Mw 7.5?8.7 earthquakes that occurred in circum-Pacific subduction zones. We compare synthetic and observed seismograms by measuring frequency-dependent amplitude and arrival time differences of the first orbit Rayleigh waves. At low frequencies, the amplitude anomalies primarily result from the spatial and temporal extent of the rupture. We then invert the amplitude and arrival time measurements to estimate the second moments of the slip distribution which describe the rupture length, width, duration, and propagation velocity of each earthquake. Comparing the rupture areas to the trench-parallel gravity anomaly (TPGA) above each rupture, we find that in 11 of the 15 events considered in this study the TPGA increases between the centroid and the limits of the rupture. Thus local increases in TPGA appear to be related to the physical conditions along the plate interface that favor rupture termination. Owing to the inherently long timescales required for forearc basin formation, the correlation between the TPGA field and rupture termination regions indicates that long-lived material heterogeneity rather than short timescale stress heterogeneities are responsible for arresting most great subduction zone ruptures.

FILE » Llenos_McGuire_2007_31584.pdf



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