← Back to Sessions

The Utility of Small Aperture Arrays for Assessing Subduction Zone Earthquakes: Insights From Temporary Nodal Deployments

Description: 

Out of network earthquakes–whether originating from an offshore tectonic source or across geopolitical boundaries–are more difficult to constrain than in-network, crustal earthquakes. This is due to a combination of factors but is largely due to a greater distance from the earthquake source to the nearest set of seismic stations. An ability to quickly constrain epicentral location and depth is especially important for Earthquake Early Warning (EEW) applications, as most current regional EEW algorithms rely on earthquake source characteristics for predicting ground motion and issuing accurate warnings. Small aperture seismic arrays offer a potential solution for quick and accurate determination of subduction-zone earthquakes through beamforming techniques and determination of a slowness vector. In addition, for remote areas that are difficult to access, utilizing multiple arrays for earthquake characterization may reduce maintenance costs without forfeiting data quality. Here, we investigate a trio of small aperture arrays deployed on Unalaska Island, Alaska, to assess the utility of arrays for fast and accurate earthquake determination. We use a dataset of earthquakes within 150 km of the arrays and occurred during the full-deployment of the three arrays. Comparing several commonly used array processing techniques (i.e. frequency-wavenumber, least-squares, and least-trimmed-squares), we find that there is no stand-alone technique that results in the most accurate earthquake location, yet different techniques offer improvements to precision. The most accurate array processing techniques and associated input parameters for a single array determined ~80% of the events within 10 degree error in backazimuth from the catalog earthquake location. The three arrays showed a consistent pattern in backazimuth error (array processing backazimuth minus catalog backazimuth) that could be easily corrected. Overall, small-aperture arrays show promising results for quickly and accurately constraining earthquake location in subduction zone settings and may prove to be a key aspect of developing an EEW system for Alaska.

Session: Network Seismology: Recent Developments, Challenges and Lessons Learned [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Cade

Student Presenter: Yes

Invited Presentation: 

Poster Number: 26

Authors