Evidence for Far-Field Wastewater Disposal Causing Recent Increases in Seismicity in Central and Northern Kansas

The rate of felt earthquakes in Kansas increased dramatically in 2014, where most seismicity initially occurred in southern Kansas, and was attributed to large-volume wastewater disposal (WD) near the Oklahoma-Kansas border. Interestingly, 9 of 10 magnitude 4+ earthquakes from 2019-2022 occurred in northern and central Kansas, where the nature of seismicity has not been explored. We investigated seismicity near the recent M4+ earthquakes using waveform cross-correlation and carefully assembled injection and extraction volumes, well stimulations, and pressure measurements. Waveform cross-correlation reveals earthquakes occur via swarms with low b-values implying a stress state that is closer to failure. Relative volumes and temporal trends indicate seismicity was primarily induced by WD into the Arbuckle. However, the large coefficient of variation of interevent times suggests primarily far-field pressure influences. In particular, Jewell County seismicity provides strong evidence of far-field forcing as it occurs >50 km from any WD wells and ~100 km from large volume WD wells, one of the largest distances of WD-induced seismicity documented. The heterogenous locations of seismicity relative to WD wells is likely controlled by preexisting unknown structures and prestresses. These results imply a large spatial influence from proposed large volume carbon sequestration in the Arbuckle and similar formations.