The 2016 forecast indicated high seismic hazard (greater than 1% probability of potentially destructive ground shaking in one-year) in five focus areas: Oklahoma-Kansas, the Raton Basin (Colorado/New Mexico border), north Texas, north Arkansas, and the New Madrid seismic zone. During 2016, several damaging induced earthquakes occurred in Oklahoma within the highest hazard region of the 2016 forecast; all of the 21 magnitude (M) ≥ 4 and 3 M ≥ 5 earthquakes occurred within the highest hazard area of the 2016 forecast. Outside the Oklahoma-Kansas focus area, two earthquakes with M ≥ 4 occurred near Trinidad, Colorado (in the Raton Basin focus area), but no earthquakes with M ≥ 2.7 were observed in the north Texas or north Arkansas focus areas. Several observations of destructive ground shaking levels were also recorded in the highest hazard region of Oklahoma.
The 2017 forecasted seismic rates are lower in regions of induced activity due to lower rates of earthquakes in 2016 compared with 2015, which may be related to the reduction of wastewater injection, caused by regulatory actions or a decrease in unconventional oil and gas production. Nevertheless, the 2017 forecasted hazard is still significantly elevated in Oklahoma compared to the hazard calculated from seismicity before 2009.
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