HR: 0800h
AN: T21A-0367    [Abstracts]
TI: Slow slip events, temperature and interseismic coupling at the Hikurangi subduction zone, New Zealand
AU: * McCaffrey, R
EM: R.McCaffrey@gns.cri.nz
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Wallace, L
EM: L.Wallace@gns.cri.nz
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Beavan, J
EM: J.Beavan@gns.cri.nz
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AB: Slow slip events (SSE) at the Hikurangi subduction zone east of the North Island, New Zealand, occur within the geodetically-determined transition from locking to free-slip and vary over a wide range of depths (10 to 50 km). While globally, shallow slow slip events are rare, most (5 of 7) observed at the Hikurangi margin are at less than 20 km depth. Shallow slow slip events follow the same scaling laws for moment v. duration as deeper ones. We estimate the temperatures, calibrated by surface heat flow data, on the fault zone where the slow slip events occur. By this estimate, which includes heating from 20 MPa of shear stress, the temperature at the geodetic transition zone where SSEs occur in the north (near 10 - 15 km depth) is estimated to be ~100 to 150°C and in the south it is ~250 to 400°C where SSEs occur at 40 - 60 km depth. At other subductions zones the locked portion of the fault is typically in the 150 to 350°C range and the transition zone occurs in the 350 - 450°C range. Temperatures estimated for the northern Hikurangi subduction zone are much less than at most transition zones and alone cannot explain the positions of the slow slip events or the geodetic transition zone. Tomography results from the Hikurangi margin suggest that trapped fluids within the fault zone are a possible control.
DE: 7209 Earthquake dynamics (1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting