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 historic C14 dated marine terraces

Japanese Examples historicC14 dated corals C14 dated marine terraces

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 Not well constrained for most megathrust systems Indonesia displays several of these effects Updip fault splaying ? Aseismic downdip slip Asthenosphere relaxation

Displacements relative to South America before and after the Mw Peru Earthquake (Perfettini et al, JGR, 2005)

(Perfettini et al, 2005) The persistent seaward motion of ARE implies a significant ‘viscous’ contribution to postseismic deformation. We deduce: V i /V f = 1.7, hence T M = 0.2 T  20yr and t r = 3.7 yr

PHUK LEWK UMLH SAMP   Time evolution of postseismic displacements is consistent with rate-strengthening frictional sliding. 5 days 90 days 30 days Chlieh et al, 2007

Postseismic deformation over 11 months

Bulasat Simanganya Years (AD) Elevation relative to modern sea level ~1370~ & 1833 Paleoseismic records Slip predictableTime- predictable or neither?

Bulasat Simanganya Years (AD) Elevation relative to modern sea level ~1370~ & 1833 Probably closer to Time-predictable

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