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Seismic Hazard Analysis for Hydraulic-Fracture Triggered Earthquakes in Oklahoma

Description: 

It has been well-publicized that Oklahoma experienced an unprecedented increase in seismicity starting about 2010 and continuing today. That seismicity peaked in 2015 when there were ~900 M3.0 or greater earthquakes that year, relative to a tectonic background rate of just 1-2 M3.0 or greater earthquakes per year prior to 2009. Many of those events are now understood to have been induced by wastewater disposal, some of which caused moderate but not widespread damage to the rural communities in which they occurred. While most public and regulatory attention has historically been focused on wastewater disposal into the Ordovician-age Arbuckle Group as a causal mechanism, in the last few years hydraulic fracturing (HF) triggers most of the induced seismicity in the state. We will report on our recent efforts to categorize HF-triggered seismicity, over the last decade, through statistical analysis. During the last decade and increasingly as the network has expanded and event detectability has improved through implementation of machine-learning, we find that almost 16% of HF completions are associated with the occurrence of an earthquake. Of those ~8,000 earthquakes associated with HF, ~1,000 were felt and reported to the USGS DYFI. We will discuss a couple of anomalous cases of larger than expected reported intensities, which include significant amplification of seismic waves due to local geology. One of those was a M3.2 HF-triggered earthquake that led to reports of light damage in southern Canadian County, OK. Our findings have important implications for mitigation of HF well completion seismicity as it is occurring and can guide best practices for future long-term geostorage and geothermal projects.

Session: Induced Earthquakes: Source Characteristics, Mechanisms, Stress Field Modeling and Hazards - I

Type: Oral

Date: 5/1/2024

Presentation Time: 08:15 AM (local time)

Presenting Author: Jacob

Student Presenter: No

Invited Presentation: 

Authors