Episodic tremor and slip events in on south-central Alaska megathrust

September 2010 episodic tremor and slip event. (a) Cumulative slip and tremors. The black arrows indicate the observed static offsets tipped with 1-sigma confidence ellipses and the blue arrows the model predictions. Tremors are color-coded by day of September 2010. Black dots indicate tremor locations outside September 2010. (b) North component of the GPS time series of ATW2. (c) September 2010 tremor activity projected along the profile AA’ shown in a. The 8 km/day propagation speed is indicated.

Project Summary 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.

Tools GPS position time series and tectonic tremors

Geographic Location South-central Alaska subduction zone

Group Members Involved Baptiste Rousset <Email> <Personal Web Site>
Noel Bartlow, Roland Bürgmann

Project Duration 2018 - 2019

More Information JGR article < rousset et al., 2019 >