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David D. Jackson - One of the best experts on this subject based on the ideXlab platform.
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earthquake prediction and forecasting
Geophysical monograph, 2013Co-Authors: David D. JacksonAbstract:Prospects for earthquake prediction and forecasting, and even their definitions, are actively debated. Here, forecasting means estimating the future earthquake rate as a function of location, time, and magnitude. Forecasting becomes prediction when we identify special conditions that make the immediate probability much higher than usual and high enough to justify exceptional action. Proposed precursors run from aeronomy to zoology, but no identified phenomenon consistently precedes Earthquakes. The reported prediction of the 1975 Haicheng, China earthquake is often proclaimed as the most successful, but the success is questionable. An earthquake predicted to occur near Parkfield, California in 1988±5 years has not happened. Why is prediction so hard? Earthquakes start in a tiny volume deep within an opaque medium; we do not know their boundary conditions, initial conditions, or material properties well; and earthquake precursors, if any, hide amongst unrelated anomalies. Earthquakes cluster in space and time, and following a quake earthquake probability spikes. Aftershocks illustrate this clustering, and later Earthquakes may even surpass earlier ones in size. However, the main shock in a cluster usually comes first and causes the most damage. Specific models help reveal the physics and allow intelligent disaster response. Modeling stresses from past Earthquakes may improve forecasts, but this approach has not yet been validated prospectively. Reliable prediction of individual quakes is not realistic in the foreseeable future, but probabilistic forecasting provides valuable information for reducing risk. Recent studies are also leading to exciting discoveries about Earthquakes.
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Importance of small Earthquakes for stress transfers and earthquake triggering : Stress transfer, earthquake triggering, and time-dependent seismic hazard
Journal of Geophysical Research, 2005Co-Authors: Agnès Helmstetter, Yan Y. Kagan, David D. JacksonAbstract:[i] We estimate the relative importance of small and large Earthquakes for static stress changes and for earthquake triggering, assuming that Earthquakes are triggered by static stress changes and that Earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other Earthquakes increase with m as ∼10 Dm/2 . The stronger the spatial clustering, the larger the influence of small Earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small Earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10 αm , where α = 1.05 ± 0.05. We also find that the magnitude distribution of triggered Earthquakes is independent of the triggering earthquake's magnitude m. When α b, small Earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D 2, close to the value D = 2a = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D 2b implies that small Earthquakes are as important as larger ones for stress transfers between Earthquakes and that considering stress changes induced by small Earthquakes should improve models of earthquake interactions.
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Importance of small Earthquakes for stress transfers and earthquake triggering
Journal of Geophysical Research, 2005Co-Authors: Agnès Helmstetter, Yan Y. Kagan, David D. JacksonAbstract:[1] We estimate the relative importance of small and large Earthquakes for static stress changes and for earthquake triggering, assuming that Earthquakes are triggered by static stress changes and that Earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other Earthquakes increase with m as similar to 10(Dm/2). The stronger the spatial clustering, the larger the influence of small Earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small Earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10(alpha m), where alpha = 1.05 +/- 0.05. We also find that the magnitude distribution of triggered Earthquakes is independent of the triggering earthquake's magnitude m. When alpha approximate to b, small Earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D approximate to 2, close to the value D = 2 alpha = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D approximate to 2b implies that small Earthquakes are as important as larger ones for stress transfers between Earthquakes and that considering stress changes induced by small Earthquakes should improve models of earthquake interactions.
Agnès Helmstetter - One of the best experts on this subject based on the ideXlab platform.
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Importance of small Earthquakes for stress transfers and earthquake triggering : Stress transfer, earthquake triggering, and time-dependent seismic hazard
Journal of Geophysical Research, 2005Co-Authors: Agnès Helmstetter, Yan Y. Kagan, David D. JacksonAbstract:[i] We estimate the relative importance of small and large Earthquakes for static stress changes and for earthquake triggering, assuming that Earthquakes are triggered by static stress changes and that Earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other Earthquakes increase with m as ∼10 Dm/2 . The stronger the spatial clustering, the larger the influence of small Earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small Earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10 αm , where α = 1.05 ± 0.05. We also find that the magnitude distribution of triggered Earthquakes is independent of the triggering earthquake's magnitude m. When α b, small Earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D 2, close to the value D = 2a = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D 2b implies that small Earthquakes are as important as larger ones for stress transfers between Earthquakes and that considering stress changes induced by small Earthquakes should improve models of earthquake interactions.
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Importance of small Earthquakes for stress transfers and earthquake triggering
Journal of Geophysical Research, 2005Co-Authors: Agnès Helmstetter, Yan Y. Kagan, David D. JacksonAbstract:[1] We estimate the relative importance of small and large Earthquakes for static stress changes and for earthquake triggering, assuming that Earthquakes are triggered by static stress changes and that Earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other Earthquakes increase with m as similar to 10(Dm/2). The stronger the spatial clustering, the larger the influence of small Earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small Earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10(alpha m), where alpha = 1.05 +/- 0.05. We also find that the magnitude distribution of triggered Earthquakes is independent of the triggering earthquake's magnitude m. When alpha approximate to b, small Earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D approximate to 2, close to the value D = 2 alpha = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D approximate to 2b implies that small Earthquakes are as important as larger ones for stress transfers between Earthquakes and that considering stress changes induced by small Earthquakes should improve models of earthquake interactions.
Norishige Hatakeyama - One of the best experts on this subject based on the ideXlab platform.
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emergence and disappearance of interplate repeating Earthquakes following the 2011 m9 0 tohoku oki earthquake slip behavior transition between seismic and aseismic depending on the loading rate
Journal of Geophysical Research, 2017Co-Authors: Norishige Hatakeyama, Naoki Uchida, Toru Matsuzawa, Wataru NakamuraAbstract:We investigated spatiotemporal change in the interplate seismic activity following the 2011 Tohoku-oki earthquake (M9.0) in the region where interseismic interplate coupling was relatively weak and large postseismic slip was observed. We classified Earthquakes by their focal mechanisms to identify the interplate events and conducted hypocenter relocation to examine the detailed spatiotemporal distribution of interplate Earthquakes in the mostly creeping area. The results show that many interplate Earthquakes, including M~6 events, emerged immediately after the Tohoku-oki earthquake in areas where very few interplate Earthquakes had been observed in the 88 previous years. The emergent Earthquakes include repeating sequences, and the extremely long quiescence of small to moderate Earthquakes before the Tohoku-oki earthquake suggests that the source areas for the post-M9 events slipped aseismically during the quiescence. The repeaters’ magnitudes decayed over time following the Tohoku-oki earthquake and some sequences disappeared within a year. The emergence of interplate Earthquakes suggests that areas where aseismic slip had been dominant before the Tohoku-oki earthquake, started to cause seismic slip after the earthquake, probably due to the increased loading rate from the afterslip. The magnitude decrease and disappearance of repeaters can be interpreted as shrinkage in seismic areas around the repeaters’ sources as the loading rate decreased due to the afterslip decay over time. These observations suggest that changes in the loading rate can cause slip behavior transition between seismic and aseismic. This indicates that such loading-rate-dependent slip behavior plays an important role in the spatiotemporal distribution of Earthquakes in interplate seismogenic zones.
Takuya Nishimura - One of the best experts on this subject based on the ideXlab platform.
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Main Results from the Program Promotion Panel for Subduction-Zone Earthquakes
Journal of Disaster Research, 2020Co-Authors: Kazushige Obara, Takuya NishimuraAbstract:Understanding the occurrence mechanism of subduction zone Earthquakes scientifically is intrinsically important for not only forecast of future subduction Earthquakes but also disaster mitigation for strong ground motion and tsunami accompanied by large Earthquakes. The Program Promotion Panel for Subduction-zone Earthquakes mainly focused on interplate megathrust Earthquakes in the subduction zones and the research activity included collection and classification of historical data on earthquake phenomena, clarifying the current earthquake phenomena and occurrence environment of earthquake sources, modelling earthquake phenomena, forecast of further earthquake activity based on monitoring crustal activity and precursory phenomena, and development of observation and analysis technique. Moreover, we studied the occurrence mechanism of intraslab Earthquakes within the subducting oceanic plate. Five-year observational research program actually produced enormous results for deep understanding of subduction zone Earthquakes phenomena, especially in terms of slow Earthquakes, infrequent huge Earthquakes, and intraslab Earthquakes. This paper mainly introduces results from researches on these phenomena in subduction zones.
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the slow earthquake spectrum in the japan trench illuminated by the s net seafloor observatories
Science, 2019Co-Authors: T Nishikawa, Naoki Uchida, Takuya Nishimura, Takanori Matsuzawa, Kazuaki Ohta, Satoshi IdeAbstract:Investigating slow earthquake activity in subduction zones provides insight into the slip behavior of megathrusts, which can provide important clues about the rupture extent of future great Earthquakes. Using the S-net ocean-bottom seismograph network along the Japan Trench, we mapped a detailed distribution of tectonic tremors, which coincided with very-low-frequency Earthquakes and a slow slip event. Compiling these and other related observations, including repeating Earthquakes and earthquake swarms, we found that the slow earthquake distribution is complementary to the Tohoku-Oki earthquake rupture. We used our observations to divide the megathrust in the Japan Trench into three along-strike segments characterized by different slip behaviors. We found that the rupture of the Tohoku-Oki earthquake, which nucleated in the central segment, was terminated by the two adjacent segments.
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coseismic and postseismic slip of the 2011 magnitude 9 tohoku oki earthquake
Nature, 2011Co-Authors: Shinzaburo Ozawa, Takuya Nishimura, Hisashi Suito, Tomokazu Kobayashi, Mikio Tobita, Tetsuro ImakiireAbstract:Detailed analysis of Global Positioning System data from Japan's Geospatial Information Authority network provides a record of coseismic and postseismic slip distribution on the megathrust fault where the magnitude-9.0 Tohoku-Oki earthquake occurred on 11 March 2011. The coseismic slip area stretches some 400 kilometres along the Japan trench, matching the area of the preseismic locked zone. Afterslip is now overlapping the coseismic slip area and expanding into the surrounding regions. The authors conclude that such geodetic data could help to improve the forecasting of earthquake potential along other subduction zones. In the accompanying News & Views, Jean-Philippe Avouac discusses current models for assessing seismic hazard. Most large Earthquakes occur along an oceanic trench, where an oceanic plate subducts beneath a continental plate. Massive Earthquakes with a moment magnitude, Mw, of nine have been known to occur in only a few areas, including Chile, Alaska, Kamchatka and Sumatra. No historical records exist of a Mw = 9 earthquake along the Japan trench, where the Pacific plate subducts beneath the Okhotsk plate, with the possible exception of the ad 869 Jogan earthquake1, the magnitude of which has not been well constrained. However, the strain accumulation rate estimated there from recent geodetic observations is much higher than the average strain rate released in previous interplate Earthquakes2,3,4,5,6. This finding raises the question of how such areas release the accumulated strain. A megathrust earthquake with Mw = 9.0 (hereafter referred to as the Tohoku-Oki earthquake) occurred on 11 March 2011, rupturing the plate boundary off the Pacific coast of northeastern Japan. Here we report the distributions of the coseismic slip and postseismic slip as determined from ground displacement detected using a network based on the Global Positioning System. The coseismic slip area extends approximately 400 km along the Japan trench, matching the area of the pre-seismic locked zone4. The afterslip has begun to overlap the coseismic slip area and extends into the surrounding region. In particular, the afterslip area reached a depth of approximately 100 km, with Mw = 8.3, on 25 March 2011. Because the Tohoku-Oki earthquake released the strain accumulated for several hundred years, the paradox of the strain budget imbalance may be partly resolved. This earthquake reminds us of the potential for Mw ≈ 9 Earthquakes to occur along other trench systems, even if no past evidence of such events exists. Therefore, it is imperative that strain accumulation be monitored using a space geodetic technique to assess earthquake potential.
A. Helmstetter - One of the best experts on this subject based on the ideXlab platform.
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Importance of small Earthquakes for stress transfers and earthquake triggering
Journal of Geophysical Research, 2005Co-Authors: A. Helmstetter, Yan Kagan, David JacksonAbstract:We estimate the relative importance of small and large Earthquakes for static stress changes and for earthquake triggering, assuming that Earthquakes are triggered by static stress changes and that Earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other Earthquakes increase with m as 10Dm/2. The stronger the spatial clustering, the larger the influence of small Earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small Earthquakes collectively dominate stress transfer and earthquake triggering, because their greater frequency overcomes their smaller individual triggering potential. Using a Southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10 m, where = 1.05 ± 0.05. We also find that the magnitude distribution of triggered Earthquakes is independent of the triggering earthquake's magnitude m. When b, small Earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for Southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. [2003] catalog and D = 1.73 for the Hauksson et al. [2003] catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with inter-event times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D 2, close to the value D = 2 = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D 2b implies that small Earthquakes are as important as larger ones for stress transfers between Earthquakes, and that considering stress changes induced by small Earthquakes should improve models of earthquake interactions.
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Is Earthquake Triggering Driven by Small Earthquakes?
Physical Review Letters, 2003Co-Authors: A. HelmstetterAbstract:Using a catalog of seismicity for Southern California, we measure how the number of triggered Earthquakes increases with the earthquake magnitude. The trade-off between this relation and the distribution of earthquake magnitudes controls the relative role of small compared to large Earthquakes. We show that seismicity triggering is driven by the smallest Earthquakes, which trigger fewer events than larger Earthquakes, but which are much more numerous. We propose that the non-trivial scaling of the number of triggered Earthquakes emerges from the fractal spatial distribution of seismicity.
