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35 results on '"Keranen, Katie"'

7. Magma Reservoir Below Laguna del Maule Volcanic Field, Chile, Imaged With Surface‐Wave Tomography

Author

Wespestad, Crystal E., primary, Thurber, Clifford H., additional, Andersen, Nathan L., additional, Singer, Brad S., additional, Cardona, Carlos, additional, Zeng, Xiangfang, additional, Bennington, Ninfa L., additional, Keranen, Katie, additional, Peterson, Dana E., additional, Cordell, Darcy, additional, Unsworth, Martyn, additional, Miller, Craig, additional, and Williams‐Jones, Glyn, additional

Published
2019
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10. A Community Experiment to Record the Full Seismic Wavefield in Oklahoma

Author

Sweet, Justin R., primary, Anderson, Kent R., additional, Bilek, Susan, additional, Brudzinski, Michael, additional, Chen, Xiaowei, additional, DeShon, Heather, additional, Hayward, Chris, additional, Karplus, Marianne, additional, Keranen, Katie, additional, Langston, Charles, additional, Lin, Fan‐Chi, additional, Beatrice Magnani, M., additional, and Woodward, Robert L., additional

Published
2018
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14. Tsunamigenic structures in a creeping section of the Alaska subduction zone

Author

Bécel, Anne, primary, Shillington, Donna J., additional, Delescluse, Matthias, additional, Nedimović, Mladen R., additional, Abers, Geoffrey A., additional, Saffer, Demian M., additional, Webb, Spahr C., additional, Keranen, Katie M., additional, Roche, Pierre-Henri, additional, Li, Jiyao, additional, and Kuehn, Harold, additional

Published
2017
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28. Low stress drops observed for aftershocks of the 2011 Mw5.7 Prague, Oklahoma, earthquake

Author

Sumy, Danielle F., Neighbors, Corrie J., Cochran, Elizabeth S., and Keranen, Katie M.

Abstract

In November 2011, three Mw= 4.8 earthquakes and thousands of aftershocks occurred along the structurally complex Wilzetta fault system near Prague, Oklahoma. Previous studies suggest that wastewater injection induced a Mw4.8 foreshock, which subsequently triggered a Mw5.7 mainshock. We examine source properties of aftershocks with a standard Brune-type spectral model and jointly solve for seismic moment (M0), corner frequency (f0), and kappa (?) with an iterative Gauss-Newton global downhill optimization method. We examine 934 earthquakes with initial moment magnitudes (Mw) between 0.33 and 4.99 based on the pseudospectral acceleration and recover reasonable M0, f0, and ?for 87 earthquakes with Mw1.83–3.51 determined by spectral fit. We use M0and f0to estimate the Brune-type stress drop, assuming a circular fault and shear-wave velocity at the hypocentral depth of the event. Our observations suggest that stress drops range between 0.005 and 4.8 MPa with a median of 0.2 MPa (0.03–26.4 MPa with a median of 1.1 MPa for Madariaga-type), which is significantly lower than typical eastern United States intraplate events (>10 MPa). We find that stress drops correlate weakly with hypocentral depth and magnitude. Additionally, we find the stress drops increase with time after the mainshock, although temporal variation in stress drop is difficult to separate from spatial heterogeneity and changing event locations. The overall low median stress drop suggests that the fault segments may have been primed to fail as a result of high pore fluid pressures, likely related to nearby wastewater injection. We investigate the amount of stress released along the fault during the aftershocks of the induced 2011 M5.7 Prague, Oklahoma earthquake and find that the stress release is very small compared to other natural earthquakes like the 2011 M5.8 Mineral, Virginia, earthquake. The difference in the stress release may be an indicator as to whether an earthquake is considered induced or natural and shows the importance of wastewater injection in triggering earthquake activity. Median Brune-type stress drops of 0.2 MPa for 2011 Mw5.7 Prague, Oklahoma, aftershocksStress drops are lower than typically reported for eastern U.S. intraplate earthquakesLow stress drops suggest that faults may have been primed to fail due to nearby wastewater injection

Published
2017
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33. Potentially induced earthquakes in Oklahoma, USA: Links between wastewater injection and the 2011 Mw 5.7 earthquake sequence.

Author

Keranen, Katie M., Savage, Heather M., Abers, Geoffrey A., and Cochran, Elizabeth S.

Subjects
*SEISMOLOGICAL research, *EARTHQUAKE damage, *EARTHQUAKE aftershocks, *GEOLOGIC faults
Abstract

Significant earthquakes are increasingly occurring within the continental interior of the United States, including five of moment magnitude (Mw) ≥5.0 in 2011 alone. Concurrently, the volume of fluid injected into the subsurface related to the production of unconventional resources continues to rise. Here we identify the largest earthquake potentially related to injection, an Mw 5.7 earthquake in November 2011 in Oklahoma. The earthquake was felt in at least 17 states and caused damage in the epicentral region. It occurred in a sequence, with 2 earthquakes of Mw 5.0 and a prolific sequence of aftershocks. We use the aftershocks to illuminate the faults that ruptured in the sequence, and show that the tip of the initial rupture plane is within ~200 m of active injection wells and within ~1 km of the surface; 30% of early aftershocks occur within the sedimentary section. Subsurface data indicate that fluid was injected into effectively sealed compartments, and we interpret that a net fluid volume increase after 18 yr of injection lowered effective stress on reservoir-bounding faults. Significantly, this case indicates that decades-long lags between the commencement of fluid injection and the onset of induced earthquakes are possible, and modifies our common criteria for fluid-induced events. The progressive rupture of three fault planes in this sequence suggests that stress changes from the initial rupture triggered the successive earthquakes, including one larger than the first. [ABSTRACT FROM AUTHOR]

Published
2013
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35. Connections between subducted sediment, pore-fluid pressure, and earthquake behavior along the Alaska megathrust.

Author

Jiyao Li, Shillington, Donna J., Saffer, Demian M., Bécel, Anne, Nedimović, Mladen R., Kuehn, Harold, Webb, Spahr C., Keranen, Katie M., and Abers, Geoffrey A.

Subjects
*FLUID pressure, *EARTHQUAKES, *SUBDUCTION zones, *SEISMIC reflection method, *INDUCED seismicity
Abstract

Variations in pore-fluid pressure along subduction megathrusts are often invoked to explain differences in fault slip behavior between margins. However, many other parameters vary between subduction zones, making it difficult to isolate the causes of elevated pore fluid pressures and their effects on megathrust behavior. Here we show evidence from pre-stack depth migrations of multichannel seismic reflection data along the subduction zone off the Alaska Peninsula for significant, systematic along-strike variations in the thickness, continuity, P-wave velocity, and estimated pore-fluid pressure of the subducting sediment layer that lines the shallow plate interface within 25 km of the trench. These variations appear to correlate with changes in seismicity, locking, and earthquake rupture history. The currently locked and seismically quiet Semidi segment has a continuous, thick (600-900 m) subducted sediment layer that is characterized by low seismic velocities and elevated pore pressure (λ* ≈ 0.4-0.8). The subducted sediment in the neighboring Shumagin Gap, a region with low geodetic coupling and abundant small earthquakes, is thinner, irregular and has lower pore pressure (λ* < 0.2-0.3). We suggest that the thicker and weakly faulted sediment layer entering the trench at Semidi is associated with a continuous and overpressured sediment layer lining the shallow plate interface, but forms a large coherent asperity as it dewaters and consolidates at greater depths, thus favoring large earthquakes. In contrast, thinner incoming sediment disrupted by outer rise faulting at Shumagin results in a plate interface without elevated pore-fluid pressures, but which is heterogeneous and complex at all depths, contributing to creep and frequent small earthquakes. [ABSTRACT FROM AUTHOR]

Published
2018
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