Exploring Hypocenter Uncertainty in the Fort Worth Basin, North Texas
Date: 4/24/2019
Time: 06:00 PM
Room: Grand Ballroom
From 2008 to 2018, local seismic research networks operated by Southern Methodist University (SMU) provided basic earthquake data needed to assess seismic hazard related to induced earthquakes in the Fort Worth Basin, north Texas. Network design strategies focused on providing accurate hypocenter and focal mechanism information, and resulting catalog generated using GENLOC algorithms within Antelope is called the North Texas Earthquake Study (NTXES) catalog. As the research evolved, the location algorithms and 1D velocity models used for earthquake location have changed. Using the NTXES catalog, we explore how the formal uncertainties, represented by 68% confidence ellipses, capture or do not capture bias due to velocity model or location algorithm. We show that when at least one sensor is within hypocentral depth (2-10 km), the NTXES catalog changes due to velocity model and standard algorithms deviate on the order of 100-300 m. We will also present tests using double-difference relative techniques and Bayesian methods. Note, however, for studies of induced earthquakes even a systematic deepening ~150 m is enough to move many earthquakes from the rock unit used for injection into the crystalline basement, and can be considered significant for detailed research studies. Using co-located 3D seismic reflection data where available, we establish the NTXES dataset as best estimate of ground-truth and compare locations in space to epicenters reported by the National Earthquake Information Center (NEIC) and the Texas Seismic Network (TexNet). We seek to better quantify and understand hypocentral uncertainty in NEIC and TexNet hypocenters in the Fort Worth Basin over time because 1) many significant felt earthquakes in the basin, including the first earthquakes along most triggered faults, were only reported by the NEIC and 2) TexNet location operations are now well-established and the catalog readily available online, whereas SMU operations and catalog are temporary in nature.
Presenting Author: Heather R. DeShon
Authors
Heather R DeShon hdeshon@smu.edu Southern Methodist University, Dallas, Texas, United States Presenting Author
Corresponding Author
|
Louis Quinones lquinones@smu.edu Southern Methodist University, Dallas, Texas, United States |
Oner Sufri osufri@smu.edu Southern Methodist University, Dallas, Texas, United States |
Stephen Arrowsmith sarrowsmith@smu.edu Southern Methodist University, Dallas, Texas, United States |
Alexandros Savvaidis alexandros.savvaidis@beg.utexas.edu University of Texas at Austin, Austin, Texas, United States |
Chris Hayward hayward@mail.isem.smu.edu Southern Methodist University, Dallas, Texas, United States |
Exploring Hypocenter Uncertainty in the Fort Worth Basin, North Texas
Category
From Drifting to Anchored: Advances in Improving Absolute Hypocenter Location Accuracy for Natural, Induced and Explosion Seismic Events