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Earthquake clustering and statistics at the Alaska Peninsula

Description: 

The Alaska Peninsula section of the Alaska-Aleutian subduction zone exhibits notable along-strike variations in seismic activity and plate coupling. These variations reflect heterogeneities in the megathrust and are presumably controlled by the sedimentary and crustal structures of the subducting slab and the overriding plate. However, due to the limited seismic and geodetic data, the megathrust heterogeneities are not well defined in detail. Here, we try to explore the megathrust heterogeneities with a more complete regional earthquake catalog powered by machine learning techniques. We used the deep-learning earthquake detection package to analyze seismic data in the Alaska Peninsula and adjacent regions from 2018 to 2021, including the Alaska Amphibious Community Seismic Experiment (AACSE), EarthScope Transportable Array, Alaska regional network, National Tsunami Warning Center Alaska Seismic Network, and Global Seismograph Network. With a two-month test dataset, we achieved a 10.4% precision score, implying the potential of an almost 10 times larger catalog. However, the recall score is only 56.7%, indicating that the detection accuracy needs to be improved, particularly on OBS data. Then all detected phases are associated using a machine-learning-based associator GaMMA. The test on manual picks from the ACE catalog has a precision of 0.6 and a recall of 0.99, showing there is a large space to improve. We will retrain the deep-learning models using the manually picked regional earthquake catalog to improve the accuracy of detection and improve the associator to achieve a better performance, then apply them to the three-year dataset. The new catalog will present more clues about the characteristics of the plate interface, especially near the trench. It will also help us observe variations of outer-rise seismicity in the incoming plate, as outer-rise faulting is regarded as one of the controlling factors on the along-strike variations of the entire subduction zone. More analyses including the delineation of fault systems and defining the aftershock zones of three recent large earthquakes will be done.

Session: Subduction Zone Structure From Trench to Arc [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Yaqi Jie

Student Presenter: Yes

Invited Presentation: 

Authors