Spatiotemporal variability of b-values in regions of induced seismicity in the Central United States

Margaret E. Glasgow, Rayming Liang, Elizabeth S. Cochran, Mohammadreza Jamalreyhani, & Ruijia Wang

Submitted September 8, 2024, SCEC Contribution #13940, 2024 SCEC Annual Meeting Poster #050

This study investigates the spatial and temporal variations in b-values associated with induced seismicity in the Central United States. B-value is the slope of earthquake magnitude versus event frequency distribution in log-space. A b-value of ~1 is consistent with the Gutenberg-Richter law. However, b-values deviate from 1 in some settings, like those with high heat flow or fluid flow, and are often considered an indicator of stress. For example, in some laboratory experiments, an increase in b-value is correlated with stress release. High b-values have been associated with hydraulic fracturing and geothermal stimulation, whereas a range of b-values have been associated with wastewater injection. We calculate b-values using the b-positive method for multiple regions of fluid-injection induced seismicity in the Central United States. These include the Raton Basin on the Colorado–New Mexico border and the oil and gas production field on the Oklahoma–Kansas (OK-KS) border. The Raton Basin catalog contains ~95,000 earthquakes and spans from 2016–2024. The OK-KS catalog contains ~310,000 earthquakes and spans from 2010–2020. We generate b-value maps after calculating a b-value for each earthquake in the catalog by considering the population of nearby events in space (e.g., 400 closest). Broad variability in b-value and spatial coherence is observed for both catalogs. The b-value ranges from 0.5–2.0 for the Raton Basin catalog and 0.6–1.7 for the OK-KS catalog. We also consider the b-value maps year-by-year and note that some regions have stable b-values through time, whereas others can vary significantly. To better understand the b-value variability in space and time, we investigate the wastewater injection records and crustal heat flow maps for our study areas.

Key Words
induced, earthquakes, b-value, stress, wastewater, injection

Citation
Glasgow, M. E., Liang, R., Cochran, E. S., Jamalreyhani, M., & Wang, R. (2024, 09). Spatiotemporal variability of b-values in regions of induced seismicity in the Central United States . Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology