Weeks-Long and Years-Long Slow Slip and Tectonic Tremor Episodes on the South...

Rousset, B., Y. Fu, N. Bartlow, and R. Burgmann (2019), Weeks-Long and Years-Long Slow Slip and Tectonic Tremor Episodes on the South Central Alaska Megathrust, J. Geophys. Res., 124, 13,392-13,403, doi:10.1029/2019JB018724.

We jointly investigate aseismic slip transients and tremor activity in south central Alaska. Near the eastern downdip edge of the Mw 9.2 1964 Prince Williams earthquake rupture, kinematic modeling of the Mw = 7.6 2009–2013 slow slip event suggests cumulative transient slip of up to 55 cm. During this 5-year transient event, tectonic tremors were co-located with the inferred aseismic slip zone and occurred in weeks-long bursts of events. A short-term transient deformation event is observed in the GPS time series spanning a tremor burst in September 2010. The time-dependent slip modeling of this Mw = 6.9 subevent shows that it migrated along strike with tremor at speeds of ∼8 km/day and with slip rates of ∼3 mm/day. It released 9% of the 5-year transient event total moment in 1.4% of its duration. The decomposition of GPS time series relative to tremor times during the whole 5-year transient event shows that GPS site velocities were on average three to six times higher during tremor bursts than in between, suggesting that slip pulses are generally associated with tremor bursts. This inference is strengthened by the decomposition of the GPS time series after the 5-years-long deformation event, during which the plate interface is being loaded in between the short-duration events and slips at times of tremor bursts. The 5-years-long transient deformation event could either represent a cluster of short-term events or be the sum of short-term ETS events and a smooth long-term slip event located updip.

PDF of Publication: 
Download from publisher's website.
Research Program: 
Earth Surface & Interior Program (ESI)