Table 1.

Earthquake groups as located in this study and as reported by the NEIC and the ANF. Reports the number of earthquakes in each group and quality category. Quality is assigned considering number and geographic distribution of seismic data used for location, with A indicating best locations. Distances listed are for all injection wells within 5 km, if such exist, from closest A-quality epicenter in each group, if such exists

County and Fig. 2 label of groupQuakes rept. by NEICQuakes rept. by ANFQuakes identified in this studyDistance: nearest wells (km)
Quality AQuality BQuality CCross-correlation
Wise W-11--11.6, 3.4, 4.5
Tarrant T-W-2-1235.5
Tarrant DFW2324-31.3
Hood-11---1.1, 2.4, 4.0
Johnson J-A368159243.2, 3.6, 5.0
Johnson J-B--34031.6
Johnson J-C (Cleburne)235-161.8, 3.8
Johnson J-D--1---2.9*, 2.9, 3.3
Johnson J-E11-1--9.2
  • *All listed injection wells are Class II wells except for one Class I well 2.9 km from the J-D epicenter; this well’s location and injection history is virtually identical to a the Class II well near J-D (Fig. S2).