Searching for Tectonic Tremor Along the Lower Cook Inlet Portion of the Alaska-Aleutian Subduction Zone
Description:
The origin of tectonic tremor along the eastern Alaska-Aleutian subduction zone remains poorly understood. Tremor has been detected along the subduction interface in the Upper Cook Inlet (UCI) vicinity, where the inferred Yakutat microplate is undergoing subduction. This tremor is approximately coincident with slow slip events (SSEs). However, tectonic tremor has not been observed in the Lower Cook Inlet (LCI) during SSEs through 2012. We investigate whether the absence of tremor is intrinsic to SSEs in the LCI during more recent events using automatic detection. Here we present preliminary results from this effort, focusing on a likely SSE in the LCI after the 2016 Old Iliamna earthquake. We selected stations from the Southern Alaska Lithosphere and Mantle Observation Network (ZE), Alaska Regional Network (AK), and the USArray Transportable Array (TA) within and near the Cook Inlet that were operating during the SSE. Several months of continuous data were analyzed to identify and locate any instances of tremor, using the automated location tool Enveloc. We filtered seismic waveforms, computed envelopes, and determined event locations through a 3D grid search that optimized cross-correlations of envelopes between stations. If tremor is absent in the LCI during the 2016 SSE, this would suggest that there is a fundamental difference between how slow slip proceeds in the LCI vs. the UCI, which may be related to physical properties within the subduction zone. Conversely, the presence of tremor would provide a new seismic observation that can be used to understand the structure of and interactions between the overriding and subducting plates in this region. This investigation will help us understand how seismicity varies temporally and spatially along the Alaska-Aleutian subduction zone, which will contribute to understanding slow slip events, tremor, and megathrust hazards globally.
Session: Structure and Behavior of the Alaska-Aleutian Subduction Zone [Poster Session]
Type: Poster
Date: 5/3/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Eryck
Student Presenter: Yes
Invited Presentation:
Authors
Eryck Ochoa Presenting Author Corresponding Author eochoa3@wisc.edu University of Wisconsin–Madison |
Eva Golos golos@wisc.edu University of Wisconsin–Madison |
|
|
|
|
|
|
|
Searching for Tectonic Tremor Along the Lower Cook Inlet Portion of the Alaska-Aleutian Subduction Zone
Category
Structure and Behavior of the Alaska-Aleutian Subduction Zone