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The Time-Predictable Recurrence Model. The original models (Shimazaki & Nakata 1980) Complications and pitfalls (Thatcher 1984) Modern examples Relevance to Indonesia. Schematic Recurrence Models. Periodic Time-Predictable Slip-Predictable.
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The Time-Predictable Recurrence Model • The original models (Shimazaki & Nakata 1980) • Complications and pitfalls (Thatcher 1984) • Modern examples • Relevance to Indonesia
Schematic Recurrence Models Periodic Time-Predictable Slip-Predictable
Japanese Examples historic
Japanese Examples C14 dated marine terraces historic
Japanese Examples C14 dated marine terraces historic C14 dated corals
Japanese Examples Interplate (megathrust) Intraplate (“continental wedge”); some permanent deformation
Complications • Postseismic transients • Short-term (few years) • Long-term (decades) • Permanent deformation • Coseismic • Interseismic
Postseismic & Permanent Deformation Updip fault splaying • Not well constrained for most megathrust systems • Indonesia displays several of these effects ? Aseismic downdip slip Asthenosphere relaxation
(Perfettini et al, JGR, 2005) Displacements relative to South America before and after the Mw 8.4 2001 Peru Earthquake
(Perfettini et al, 2005) The persistent seaward motion of ARE implies a significant ‘viscous’ contribution to postseismic deformation. We deduce: Vi/Vf = 1.7, hence TM= 0.2 T20yr and tr = 3.7 yr
SAMP LEWK 90 days 5 days 30 days • Time evolution of postseismic displacements is consistent • with rate-strengthening frictional sliding. PHUK UMLH Chlieh et al, 2007
~1370 ~1600 1797 & 1833 Paleoseismic records Slip predictableTime-predictable or neither? Bulasat Elevation relative to modern sea level Simanganya Years (AD)
~1370 ~1600 1797 & 1833 Probably closer to Time-predictable Bulasat Elevation relative to modern sea level Simanganya Years (AD)
Wrightwood Example • No time- or slip-predictability on the scale of single RIs • May have multi-cycle time-predictability • May not be representative of SAF as a whole (Weldon et al. 2004)
Summary • Monitoring future postseismic deformation through cGPS will yield more complete picture of the seismic cycle • Complications to model are important for deeper understanding, but don’t affect the first-order model fit • More important: compare several locations along the megathrust