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Earthquake Locations in the Pecos, TX Region of the Delaware Basin

Session: Recent Development in Ultra-Dense Seismic Arrays with Nodes and Distributed Acoustic Sensing

Type: Oral

Date: 4/20/2021

Presentation Time: 06:15 PM Pacific

Description: 

Since 2009, there has been a dramatic increase in seismicity in the Delaware Basin of west Texas in the Pecos, TX region. Seismicity has increased by over two orders of magnitude since 2009, corresponding with an increase in oil and gas production in the basin. Approximately 3,000 earthquakes with magnitudes greater than 1.5 have been recorded within a 50 km radius of Pecos, TX since the Texas Seismological Network (TexNet) was installed in January of 2017. From January 2017 to January 2021, this time range also includes 45 ML 3+ earthquakes, and approximately 900 ML 2.0-2.9 earthquakes. Due to TexNet’s typical 25 km spacing, precise hypocenter location is challenging. Absolute epicentral error is as great as 4 km, and absolute depth error as great as 5 km. Accurate hypocenters are critically needed in the Delaware Basin to identify the structures producing these earthquakes and to determine how they are related to unconventional petroleum development and production.

To determine accurate epicenters, focal depths, and velocity structure, we designed and deployed a network of ~25 3C Magseis Fairfield Z-land 5-Hz nodes in and around the Pecos area, known as the Pecos Array. The array recorded data from November 2018 to January 2020. We performed an in-depth analysis of how well a machine learning algorithm, PhaseNet, picked phase arrivals, which were used to associate and locate events for five months from January 2019 to May 2019. We compared earthquake locations using the PhaseNet automatic picks with earthquake locations using picks from analysts at TexNet. With these two databases, we are able to compare the two picking methods and determine seismicity patterns in the area.

Presenting Author: Jenna L. Faith

Student Presenter: Yes

Authors