Non-volcanic tremor in the Alaska/Aleutian subduction zone and its relationship to slow-slip events

Abstract

"We document non-volcanic tremor (NVT) in Southcentral Alaska and the Aleutian Arc in terms of durations and locations. In Southcentral Alaska, we tabulate NVT events occurring during the summer months of each year between 1999 and 2001 to test for a relationship with a slow-slip event that occurred during this time frame. We tabulate NVT events in the Aleutians starting in the summer of 2005 through the summer of 2008. The observed NVT events in both Southcentral Alaska and the Aleutian arc are sequences of emergent pulses with frequencies of 1-10 Hz. The majority of the events have durations ranging from 5-15 minutes. In Southcentral Alaska, the majority of the NVT events locate in the region of the slow-slip event and the quantity of events decreases significantly by the summer of 2001, coinciding with the end of the slow-slip event. Locating NVT events in the Aleutians is problematic due to the linearity and sparse distribution of seismic stations. General locations are established simply by the distribution of volcano seismic networks on which the signal is observed and the strength of that signal. These general locations appear to coincide with regions where the plate interface is locked or is transitioning from creeping to locked. Furthermore, several episodes of NVT in the Aleutians occurring during times of heightened volcanic and seismic activity in the arc, suggesting large regional stress changes possibly caused by undetected slow-slip events"--Leaf iii