HR: 09:15h
AN: G31A-06    [Abstracts]
TI: Slow slip events at the Alaska Subduction Zone
AU: * Freymueller, J T
EM: jeff@giseis.alaska.edu
AF: University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK 99775, United States
AU: Ohta, Y
EM: ohta@seis.nagoya-u.ac.jp
AF: Nagoya University, Graduate School of Environmental Studies, Nagoya, Japan
AB: A large slow slip event (SSE) occurred at the Alaska subduction zone during 1998-2001 [Ohta et al., 2006, EPSL]. The SSE occurs downdip of the Prince William Sound asperity, on a section that accumulated some slip deficit before and after the SSE. During the SSE, >20,000 sq. km of the plate interface slipped >10 cm, for a cumulative moment magnitude of Mw=7.2. Slip during this event was accompanied by significant non-volcanic tremor, which located in the same area as the slip. The area of the SSE did not have significant slip in the 1964 earthquake, compared to the slip of the main asperity. Our previous work did not attempt to determine the time history of slip in the SSE, because of a lack of continuous GPS data, but a reanalysis of the data that includes a few new sites allows us to estimate the approximate time history. Based on a preliminary solution, it appears that the initiation time probably varied over the area of the SSE, implying some spatial propagation, but our ability to resolve this is very limited. The continuous GPS record suggests that that may have been at least one and possibly several smaller SSEs in the same area. These smaller events appear to last for several weeks, but because most appear at a similar time of year, it is possible that they represent an unmodeled seasonal signal instead. We will compare the displacement pattern and time history of the large SSE to the displacements to evaluate whether these smaller events actually represent SSEs on the same part of the plate interface.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Geodesy [G]
MN: 2007 Joint Assembly