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Kristine M Larson - One of the best experts on this subject based on the ideXlab platform.
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seismically and geodetically determined nondouble couple source mechanisms from the 2000 miyakejima Volcanic Earthquake swarm
Journal of Geophysical Research, 2007Co-Authors: Sarah E Minson, Roland Burgmann, Douglas S Dreger, Hiroo Kanamori, Kristine M LarsonAbstract:The Volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest Earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from Volcanic Earthquakes. Our model, the “crack + double-couple” (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July Earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two Earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July Earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional Earthquakes from this sequence and find that the CDC model fits the seismic data for these Earthquakes at least as well as established seismic moment tensor models.
Douglas S Dreger - One of the best experts on this subject based on the ideXlab platform.
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the puzzle of the 1996 bardarbunga iceland Earthquake no volumetric component in the source mechanism
Bulletin of the Seismological Society of America, 2009Co-Authors: Hrvoje Tkalcic, Douglas S Dreger, G R Foulger, Bruce R JulianAbstract:A Volcanic Earthquake with M w 5.6 occurred beneath the Bardarbunga caldera in Iceland on 29 September 1996. This Earthquake is one of a decade-long sequence of ![Graphic][1] events at Bardarbunga with non-double-couple mechanisms in the Global Centroid Moment Tensor catalog. Fortunately, it was recorded well by the regional-scale Iceland Hotspot Project seismic experiment. We investigated the event with a complete moment tensor inversion method using regional long-period seismic waveforms and a composite structural model. The moment tensor inversion using data from stations of the Iceland Hotspot Project yields a non-double-couple solution with a 67% vertically oriented compensated linear vector dipole component, a 32% double-couple component, and a statistically insignificant (2%) volumetric (isotropic) contraction. This indicates the absence of a net volumetric component, which is puzzling in the case of a large Volcanic Earthquake that apparently is not explained by shear slip on a planar fault. A possible Volcanic mechanism that can produce an Earthquake without a volumetric component involves two offset sources with similar but opposite volume changes. We show that although such a model cannot be ruled out, the circumstances under which it could happen are rare. [1]: /embed/inline-graphic-1.gif
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seismically and geodetically determined nondouble couple source mechanisms from the 2000 miyakejima Volcanic Earthquake swarm
Journal of Geophysical Research, 2007Co-Authors: Sarah E Minson, Roland Burgmann, Douglas S Dreger, Hiroo Kanamori, Kristine M LarsonAbstract:The Volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest Earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from Volcanic Earthquakes. Our model, the “crack + double-couple” (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July Earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two Earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July Earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional Earthquakes from this sequence and find that the CDC model fits the seismic data for these Earthquakes at least as well as established seismic moment tensor models.
Sarah E Minson - One of the best experts on this subject based on the ideXlab platform.
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seismically and geodetically determined nondouble couple source mechanisms from the 2000 miyakejima Volcanic Earthquake swarm
Journal of Geophysical Research, 2007Co-Authors: Sarah E Minson, Roland Burgmann, Douglas S Dreger, Hiroo Kanamori, Kristine M LarsonAbstract:The Volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest Earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from Volcanic Earthquakes. Our model, the “crack + double-couple” (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July Earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two Earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July Earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional Earthquakes from this sequence and find that the CDC model fits the seismic data for these Earthquakes at least as well as established seismic moment tensor models.
Bruce R Julian - One of the best experts on this subject based on the ideXlab platform.
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the puzzle of the 1996 bardarbunga iceland Earthquake no volumetric component in the source mechanism
Bulletin of the Seismological Society of America, 2009Co-Authors: Hrvoje Tkalcic, Douglas S Dreger, G R Foulger, Bruce R JulianAbstract:A Volcanic Earthquake with M w 5.6 occurred beneath the Bardarbunga caldera in Iceland on 29 September 1996. This Earthquake is one of a decade-long sequence of ![Graphic][1] events at Bardarbunga with non-double-couple mechanisms in the Global Centroid Moment Tensor catalog. Fortunately, it was recorded well by the regional-scale Iceland Hotspot Project seismic experiment. We investigated the event with a complete moment tensor inversion method using regional long-period seismic waveforms and a composite structural model. The moment tensor inversion using data from stations of the Iceland Hotspot Project yields a non-double-couple solution with a 67% vertically oriented compensated linear vector dipole component, a 32% double-couple component, and a statistically insignificant (2%) volumetric (isotropic) contraction. This indicates the absence of a net volumetric component, which is puzzling in the case of a large Volcanic Earthquake that apparently is not explained by shear slip on a planar fault. A possible Volcanic mechanism that can produce an Earthquake without a volumetric component involves two offset sources with similar but opposite volume changes. We show that although such a model cannot be ruled out, the circumstances under which it could happen are rare. [1]: /embed/inline-graphic-1.gif
Hiroo Kanamori - One of the best experts on this subject based on the ideXlab platform.
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seismically and geodetically determined nondouble couple source mechanisms from the 2000 miyakejima Volcanic Earthquake swarm
Journal of Geophysical Research, 2007Co-Authors: Sarah E Minson, Roland Burgmann, Douglas S Dreger, Hiroo Kanamori, Kristine M LarsonAbstract:The Volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest Earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from Volcanic Earthquakes. Our model, the “crack + double-couple” (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July Earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two Earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July Earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional Earthquakes from this sequence and find that the CDC model fits the seismic data for these Earthquakes at least as well as established seismic moment tensor models.
