Update of the USGS 2016 One-year Seismic Hazard Forecast for the Central and Eastern United States From Induced and Natural Earthquakes
Abstract
The U.S. Geological Survey released a 2016 one-year forecast for seismic hazard in the central and eastern U.S., which included the influence from both induced and natural earthquakes. This forecast was primarily based on 2015 declustered seismicity rates but also included longer-term rates, 10- and 20- km smoothing distances, earthquakes between Mw 4.7 and maximum magnitudes of 6.0 or 7.1, and 9 alternative ground motion models. Results indicate that areas in Oklahoma, Kansas, Colorado, New Mexico, Arkansas, Texas, and the New Madrid Seismic Zone have a significant chance for damaging ground shaking levels in 2016 (greater than 1% chance of exceeding 0.12 PGA and MMI VI). We evaluate this one-year forecast by considering the earthquakes and ground shaking levels that occurred during the first half of 2016 (earthquakes not included in the forecast). During this period the full catalog records hundreds of events with M ≥ 3.0, but the declustered catalog eliminates most of these dependent earthquakes and results in much lower numbers of earthquakes. The declustered catalog based on USGS COMCAT indicates a M 5.1 earthquake occurred in the zone of highest hazard on the map. Two additional earthquakes of M ≥ 4.0 occurred in Oklahoma, and about 82 earthquakes of M ≥ 3.0 occurred with 77 in Oklahoma and Kansas, 4 in Raton Basin Colorado/New Mexico, and 1 near Cogdell Texas. In addition, 72 earthquakes occurred outside the zones of induced seismicity with more than half in New Madrid and eastern Tennessee. The catalog rates in the first half of 2016 and the corresponding seismic hazard were generally lower than in 2015. For example, the zones for Irving, Venus, and Fashing, Texas; Sun City, Kansas; and north-central Arkansas did not experience any earthquakes with M≥ 2.7 during this period. The full catalog rates were lower by about 30% in Raton Basin and the Oklahoma-Kansas zones but the declustered catalog rates did not drop as much. This decrease in earthquake activity may be related to a reported decrease in wastewater disposal caused by a drop in the price of oil and by regulatory actions. For example, during 2015 and 2016 regulators in Oklahoma and Kansas took several actions to reduce the disposal volumes in high hazard areas.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S54B..01P
- Keywords:
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- 4475 Scaling: spatial and temporal;
- NONLINEAR GEOPHYSICSDE: 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGYDE: 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS