000018708 001__ 18708
000018708 005__ 20170118182237.0
000018708 04107 $$aeng
000018708 046__ $$k2017-01-09
000018708 100__ $$aToro, Gabriel
000018708 24500 $$aAnalysis of Magnitude-Spatial Trends of Induced Seismicity in Oklahoma, Usa

000018708 24630 $$n16.$$pProceedings of the 16th World Conference on Earthquake Engineering
000018708 260__ $$b
000018708 506__ $$arestricted
000018708 520__ $$2eng$$aSmall earthquakes are occurring with a high rate in Oklahoma, USA, and have been attributed to ongoing fluid injection into the crust from disposal wells in the state. The rate of mb>3 is observed to be about 2 per day, or 730 per year, which exceeds the rate in California. Seismicity is occurring in central and northern Oklahoma, although fluid injection wells are distributed throughout the state. The largest recent earthquake in the region of high seismicity is the Pawnee, Oklahoma M 5.8 earthquake on September 3, 2016, which caused damage to multiple structures. Analysis of the b-value of small earthquakes since February 2014 indicates that b-values vary in time, ranging from about 1.0 to 3.0. Also, the temporal occurrences of larger micro-earthquakes (mb>4.2) appear to follow a peak in b-values. Finally, four moderate earthquakes (M>4.9) have occurred at the edges of the region of micro-seismicity. These effects are consistent with pore pressure changes from fluid disposal wells extending to larger distances with time, affecting favorably-oriented faults in adjacent areas, and triggering earthquakes on those faults. These effects can be replicated with a simple model of crustal pore pressure changes caused by fluid injection into a permeable geologic unit, with faults oriented randomly but close to a direction favorable to rupture under crustal stress conditions with small pore pressure changes, and with an exponential distribution of fault areas leading to an exponential distribution of earthquake magnitudes. Since January 2016 the rates of fluid injection in disposal wells have been restricted by Oklahoma state officials, so occurrences and characteristics of micro-seismicity in the region likely will change.

000018708 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000018708 653__ $$ainduced seismicity; temporal seismicity changes

000018708 7112_ $$a16th World Conference on Earthquake Engineering$$cSantiago (CL)$$d2017-01-09 / 2017-01-13$$gWCEE16
000018708 720__ $$aToro, Gabriel$$iZandieh, Arash$$iMcguire, Robin
000018708 8560_ $$ffischerc@itam.cas.cz
000018708 8564_ $$s805291$$uhttps://invenio.itam.cas.cz/record/18708/files/2055.pdf$$yOriginal version of the author's contribution as presented on USB, paper 2055.
000018708 962__ $$r16048
000018708 980__ $$aPAPER