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Edward H Field - One of the best experts on this subject based on the ideXlab platform.
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a spatiotemporal clustering model for the third uniform california Earthquake Rupture forecast ucerf3 etas toward an operational Earthquake forecast
Bulletin of the Seismological Society of America, 2017Co-Authors: Edward H Field, Thomas H Jordan, Andrew J Michael, Kevin R Milner, Jeanne L Hardebeck, Morgan T Page, Nicholas J Van Der Elst, Bruce E Shaw, Maximilian J WernerAbstract:We, the ongoing Working Group on California Earthquake Probabilities, present a spatiotemporal clustering model for the Third Uniform California Earthquake Rupture Forecast (UCERF3), with the goal being to represent aftershocks, induced seismicity, and otherwise triggered events as a potential basis for operational Earthquake forecasting (OEF). Specifically, we add an epidemic‐type aftershock sequence (ETAS) component to the previously published time‐independent and long‐term time‐dependent forecasts. This combined model, referred to as UCERF3‐ETAS, collectively represents a relaxation of segmentation assumptions, the inclusion of multifault Ruptures, an elastic‐rebound model for fault‐based Ruptures, and a state‐of‐the‐art spatiotemporal clustering component. It also represents an attempt to merge fault‐based forecasts with statistical seismology models, such that information on fault proximity, activity rate, and time since last event are considered in OEF. We describe several unanticipated challenges that were encountered, including a need for elastic rebound and characteristic magnitude–frequency distributions (MFDs) on faults, both of which are required to get realistic triggering behavior. UCERF3‐ETAS produces synthetic catalogs of M ≥2.5 events, conditioned on any prior M ≥2.5 events that are input to the model. We evaluate results with respect to both long‐term (1000 year) simulations as well as for 10‐year time periods following a variety of hypothetical scenario mainshocks. Although the results are very plausible, they are not always consistent with the simple notion that triggering probabilities should be greater if a mainshock is located near a fault. Important factors include whether the MFD near faults includes a significant characteristic Earthquake component, as well as whether large triggered events can nucleate from within the Rupture zone of the mainshock. Because UCERF3‐ETAS has many sources of uncertainty, as will any subsequent version or competing model, potential usefulness needs to be considered in the context of actual applications. [Electronic Supplement:][1] Figures showing discretization, verification of the DistanceDecayCubeSampler , average simulated participation rate, and average cumulative magnitude–frequency distributions (MFDs). [1]: http://www.bssaonline.org/lookup/suppl/doi:10.1785/0120160173/-/DC1
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long term time dependent probabilities for the third uniform california Earthquake Rupture forecast ucerf3
Bulletin of the Seismological Society of America, 2015Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher Madden, David A Jackson, Andrew J MichaelAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP 2014) presents time-dependent Earthquake probabilities for the third Uniform California Earthquake Rupture Forecast (UCERF3). Building on the UCERF3 time-in- dependent model published previously, renewal models are utilized to represent elastic- rebound-implied probabilities. A new methodology has been developed that solves applicability issues in the previous approach for unsegmented models. The new meth- odology also supports magnitude-dependent aperiodicity and accounts for the historic open interval on faults that lack a date-of-last-event constraint. Epistemic uncertainties are represented with a logic tree, producing 5760 different forecasts. Results for a variety of evaluation metrics are presented, including logic-tree sensitivity analyses and comparisons to the previous model (UCERF2). For 30 yr M ! 6:7 probabilities, the most significant changes from UCERF2 are a threefold increase on the Calaveras fault and a threefold decrease on the San Jacinto fault. Such changes are due mostly to differences in the time-independent models (e.g., fault-slip rates), with relaxation of segmentation and inclusion of multifault Ruptures being particularly influential. In fact, some UCERF2 faults were simply too long to produce M 6.7 size events given the segmentation assumptions in that study. Probability model differences are also influential, with the implied gains (relative to a Poisson model) being generally higher in UCERF3. Accounting for the historic open interval is one reason. Another is an effective 27% increase in the total elastic-rebound-model weight. The exact factors influencing differences between UCERF2 and UCERF3, as well as the relative im- portance of logic-tree branches, vary throughout the region and depend on the evalu- ation metric of interest. For example, M ! 6:7 probabilities may not be a good proxy for other hazard or loss measures. This sensitivity, coupled with the approximate nature of the model and known limitations, means the applicability of UCERF3 should be evaluated on a case-by-case basis.
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uniform california Earthquake Rupture forecast version 3 ucerf3 the time independent model
Bulletin of the Seismological Society of America, 2014Co-Authors: Edward H Field, David D Jackson, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Ramon Arrowsmith, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher MaddenAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP14) present the time‐independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging Earthquakes in California. The primary achievements have been to relax fault segmentation and include multifault Ruptures, both limitations of UCERF2. The rates of all Earthquakes are solved for simultaneously and from a broader range of data, using a system‐level inversion that is both conceptually simple and extensible. The inverse problem is large and underdetermined, so a range of models is sampled using an efficient simulated annealing algorithm. The approach is more derivative than prescriptive (e.g., magnitude–frequency distributions are no longer assumed), so new analysis tools were developed for exploring solutions. Epistemic uncertainties were also accounted for using 1440 alternative logic‐tree branches, necessitating access to supercomputers. The most influential uncertainties include alternative deformation models (fault slip rates), a new smoothed seismicity algorithm, alternative values for the total rate of M w≥5 events, and different scaling relationships, virtually all of which are new. As a notable first, three deformation models are based on kinematically consistent inversions of geodetic and geologic data, also providing slip‐rate constraints on faults previously excluded due to lack of geologic data. The grand inversion constitutes a system‐level framework for testing hypotheses and balancing the influence of different experts. For example, we demonstrate serious challenges with the Gutenberg–Richter hypothesis for individual faults. UCERF3 is still an approximation of the system, however, and the range of models is limited (e.g., constrained to stay close to UCERF2). Nevertheless, UCERF3 removes the apparent UCERF2 overprediction of M 6.5–7 Earthquake rates and also includes types of multifault Ruptures seen in nature. Although UCERF3 fits the data better than UCERF2 overall, there may be areas that warrant further site‐specific investigation. Supporting products may be of general interest, and we list key assumptions and avenues for future model improvements.
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uniform california Earthquake Rupture forecast version 2 ucerf 2
Bulletin of the Seismological Society of America, 2009Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Arthur Frankel, Vipin Gupta, Thomas H Jordan, Tom Parsons, Mark D Petersen, Ross S Stein, Ray J WeldonAbstract:The 2007 Working Group on California Earthquake Probabilities (WGCEP, 2007) presents the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2). This model comprises a time-independent (Poisson-process) Earthquake rate model, developed jointly with the National Seismic Hazard Mapping Program and a time-dependent Earthquake-probability model, based on recent Earthquake rates and stress-renewal statistics conditioned on the date of last event. The models were developed from updated statewide Earthquake catalogs and fault deformation databases using a uniform methodology across all regions and implemented in the modular, extensible Open Seismic Hazard Analysis framework. The rate model satisfies integrating measures of deformation across the plate-boundary zone and is consistent with historical seismicity data. An overprediction of Earthquake rates found at intermediate magnitudes (6.5≤ M ≤7.0) in previous models has been reduced to within the 95% confidence bounds of the historical Earthquake catalog. A logic tree with 480 branches represents the epistemic uncertainties of the full time-dependent model. The mean UCERF 2 time-dependent probability of one or more M ≥6.7 Earthquakes in the California region during the next 30 yr is 99.7%; this probability decreases to 46% for M ≥7.5 and to 4.5% for M ≥8.0. These probabilities do not include the Cascadia subduction zone, largely north of California, for which the estimated 30 yr, M ≥8.0 time-dependent probability is 10%. The M ≥6.7 probabilities on major strike-slip faults are consistent with the WGCEP (2003) study in the San Francisco Bay Area and the WGCEP (1995) study in southern California, except for significantly lower estimates along the San Jacinto and Elsinore faults, owing to provisions for larger multisegment Ruptures. Important model limitations are discussed.
Thomas H Jordan - One of the best experts on this subject based on the ideXlab platform.
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a spatiotemporal clustering model for the third uniform california Earthquake Rupture forecast ucerf3 etas toward an operational Earthquake forecast
Bulletin of the Seismological Society of America, 2017Co-Authors: Edward H Field, Thomas H Jordan, Andrew J Michael, Kevin R Milner, Jeanne L Hardebeck, Morgan T Page, Nicholas J Van Der Elst, Bruce E Shaw, Maximilian J WernerAbstract:We, the ongoing Working Group on California Earthquake Probabilities, present a spatiotemporal clustering model for the Third Uniform California Earthquake Rupture Forecast (UCERF3), with the goal being to represent aftershocks, induced seismicity, and otherwise triggered events as a potential basis for operational Earthquake forecasting (OEF). Specifically, we add an epidemic‐type aftershock sequence (ETAS) component to the previously published time‐independent and long‐term time‐dependent forecasts. This combined model, referred to as UCERF3‐ETAS, collectively represents a relaxation of segmentation assumptions, the inclusion of multifault Ruptures, an elastic‐rebound model for fault‐based Ruptures, and a state‐of‐the‐art spatiotemporal clustering component. It also represents an attempt to merge fault‐based forecasts with statistical seismology models, such that information on fault proximity, activity rate, and time since last event are considered in OEF. We describe several unanticipated challenges that were encountered, including a need for elastic rebound and characteristic magnitude–frequency distributions (MFDs) on faults, both of which are required to get realistic triggering behavior. UCERF3‐ETAS produces synthetic catalogs of M ≥2.5 events, conditioned on any prior M ≥2.5 events that are input to the model. We evaluate results with respect to both long‐term (1000 year) simulations as well as for 10‐year time periods following a variety of hypothetical scenario mainshocks. Although the results are very plausible, they are not always consistent with the simple notion that triggering probabilities should be greater if a mainshock is located near a fault. Important factors include whether the MFD near faults includes a significant characteristic Earthquake component, as well as whether large triggered events can nucleate from within the Rupture zone of the mainshock. Because UCERF3‐ETAS has many sources of uncertainty, as will any subsequent version or competing model, potential usefulness needs to be considered in the context of actual applications. [Electronic Supplement:][1] Figures showing discretization, verification of the DistanceDecayCubeSampler , average simulated participation rate, and average cumulative magnitude–frequency distributions (MFDs). [1]: http://www.bssaonline.org/lookup/suppl/doi:10.1785/0120160173/-/DC1
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long term time dependent probabilities for the third uniform california Earthquake Rupture forecast ucerf3
Bulletin of the Seismological Society of America, 2015Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher Madden, David A Jackson, Andrew J MichaelAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP 2014) presents time-dependent Earthquake probabilities for the third Uniform California Earthquake Rupture Forecast (UCERF3). Building on the UCERF3 time-in- dependent model published previously, renewal models are utilized to represent elastic- rebound-implied probabilities. A new methodology has been developed that solves applicability issues in the previous approach for unsegmented models. The new meth- odology also supports magnitude-dependent aperiodicity and accounts for the historic open interval on faults that lack a date-of-last-event constraint. Epistemic uncertainties are represented with a logic tree, producing 5760 different forecasts. Results for a variety of evaluation metrics are presented, including logic-tree sensitivity analyses and comparisons to the previous model (UCERF2). For 30 yr M ! 6:7 probabilities, the most significant changes from UCERF2 are a threefold increase on the Calaveras fault and a threefold decrease on the San Jacinto fault. Such changes are due mostly to differences in the time-independent models (e.g., fault-slip rates), with relaxation of segmentation and inclusion of multifault Ruptures being particularly influential. In fact, some UCERF2 faults were simply too long to produce M 6.7 size events given the segmentation assumptions in that study. Probability model differences are also influential, with the implied gains (relative to a Poisson model) being generally higher in UCERF3. Accounting for the historic open interval is one reason. Another is an effective 27% increase in the total elastic-rebound-model weight. The exact factors influencing differences between UCERF2 and UCERF3, as well as the relative im- portance of logic-tree branches, vary throughout the region and depend on the evalu- ation metric of interest. For example, M ! 6:7 probabilities may not be a good proxy for other hazard or loss measures. This sensitivity, coupled with the approximate nature of the model and known limitations, means the applicability of UCERF3 should be evaluated on a case-by-case basis.
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uniform california Earthquake Rupture forecast version 3 ucerf3 the time independent model
Bulletin of the Seismological Society of America, 2014Co-Authors: Edward H Field, David D Jackson, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Ramon Arrowsmith, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher MaddenAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP14) present the time‐independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging Earthquakes in California. The primary achievements have been to relax fault segmentation and include multifault Ruptures, both limitations of UCERF2. The rates of all Earthquakes are solved for simultaneously and from a broader range of data, using a system‐level inversion that is both conceptually simple and extensible. The inverse problem is large and underdetermined, so a range of models is sampled using an efficient simulated annealing algorithm. The approach is more derivative than prescriptive (e.g., magnitude–frequency distributions are no longer assumed), so new analysis tools were developed for exploring solutions. Epistemic uncertainties were also accounted for using 1440 alternative logic‐tree branches, necessitating access to supercomputers. The most influential uncertainties include alternative deformation models (fault slip rates), a new smoothed seismicity algorithm, alternative values for the total rate of M w≥5 events, and different scaling relationships, virtually all of which are new. As a notable first, three deformation models are based on kinematically consistent inversions of geodetic and geologic data, also providing slip‐rate constraints on faults previously excluded due to lack of geologic data. The grand inversion constitutes a system‐level framework for testing hypotheses and balancing the influence of different experts. For example, we demonstrate serious challenges with the Gutenberg–Richter hypothesis for individual faults. UCERF3 is still an approximation of the system, however, and the range of models is limited (e.g., constrained to stay close to UCERF2). Nevertheless, UCERF3 removes the apparent UCERF2 overprediction of M 6.5–7 Earthquake rates and also includes types of multifault Ruptures seen in nature. Although UCERF3 fits the data better than UCERF2 overall, there may be areas that warrant further site‐specific investigation. Supporting products may be of general interest, and we list key assumptions and avenues for future model improvements.
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uniform california Earthquake Rupture forecast version 2 ucerf 2
Bulletin of the Seismological Society of America, 2009Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Arthur Frankel, Vipin Gupta, Thomas H Jordan, Tom Parsons, Mark D Petersen, Ross S Stein, Ray J WeldonAbstract:The 2007 Working Group on California Earthquake Probabilities (WGCEP, 2007) presents the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2). This model comprises a time-independent (Poisson-process) Earthquake rate model, developed jointly with the National Seismic Hazard Mapping Program and a time-dependent Earthquake-probability model, based on recent Earthquake rates and stress-renewal statistics conditioned on the date of last event. The models were developed from updated statewide Earthquake catalogs and fault deformation databases using a uniform methodology across all regions and implemented in the modular, extensible Open Seismic Hazard Analysis framework. The rate model satisfies integrating measures of deformation across the plate-boundary zone and is consistent with historical seismicity data. An overprediction of Earthquake rates found at intermediate magnitudes (6.5≤ M ≤7.0) in previous models has been reduced to within the 95% confidence bounds of the historical Earthquake catalog. A logic tree with 480 branches represents the epistemic uncertainties of the full time-dependent model. The mean UCERF 2 time-dependent probability of one or more M ≥6.7 Earthquakes in the California region during the next 30 yr is 99.7%; this probability decreases to 46% for M ≥7.5 and to 4.5% for M ≥8.0. These probabilities do not include the Cascadia subduction zone, largely north of California, for which the estimated 30 yr, M ≥8.0 time-dependent probability is 10%. The M ≥6.7 probabilities on major strike-slip faults are consistent with the WGCEP (2003) study in the San Francisco Bay Area and the WGCEP (1995) study in southern California, except for significantly lower estimates along the San Jacinto and Elsinore faults, owing to provisions for larger multisegment Ruptures. Important model limitations are discussed.
Valerie Thomas - One of the best experts on this subject based on the ideXlab platform.
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caltech usgs southern california seismic network scsn and southern california Earthquake data center scedc data availability for the 2019 ridgecrest sequence
Seismological Research Letters, 2020Co-Authors: Egill Hauksson, C E Yoon, Jennifer Andrews, Marcos Alvarez, Rayo Bhadha, Valerie ThomasAbstract:The 2019 M_w 6.4 and M_w 7.1 Ridgecrest Earthquake sequence occurred in the eastern California shear zone (ECSZ). The mainshock Ruptured the Little Lake fault zone, and aftershocks extended from the Garlock fault in the south to the southern end of the 1872 M 7.5 Owens Valley Earthquake Rupture in the north. We present data from the Southern California Seismic Network (SCSN) and partner seismic networks recorded by the SCSN in the region. These time‐series data and related products such as the SCSN Earthquake picks and catalogs, available from the Southern California Earthquake Data Center, provide the most comprehensive seismic datasets for the 2019 Ridgecrest Earthquake sequence.
Andreas K. Kronenberg - One of the best experts on this subject based on the ideXlab platform.
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fracture surface energy of the punchbowl fault san andreas system
Nature, 2005Co-Authors: Judith S Chester, F M Chester, Andreas K. KronenbergAbstract:The energetics of Earthquake Rupture, slip-weakening and Rupture surface formation are poorly understood. By measuring the energy associated with fracture damage along the Punchbowl fault in the Devil's Punchbowl Los Angeles County Park, part of the San Andreas system, Chester et al. show that the fracture surface energy for Rupture along a mature fault of this type accounts for only a small fraction of the energy released during large Earthquakes as determined by seismologists. This suggests that mechanisms such as melt lubrication and thermal pressurization are responsible for slip weakening. Fracture energy is a form of latent heat required to create an Earthquake Rupture surface and is related to parameters governing Rupture propagation and processes of slip weakening1,2,3. Fracture energy has been estimated from seismological and experimental rock deformation data4,5,6,7,8, yet its magnitude, mechanisms of Rupture surface formation and processes leading to slip weakening are not well defined8,9,10. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault11,12 in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large Earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by Earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during Earthquake Rupture.
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fracture surface energy of the punchbowl fault san andreas system
Nature, 2005Co-Authors: Judith S Chester, F M Chester, Andreas K. KronenbergAbstract:Fracture energy is a form of latent heat required to create an Earthquake Rupture surface and is related to parameters governing Rupture propagation and processes of slip weakening. Fracture energy has been estimated from seismological and experimental rock deformation data, yet its magnitude, mechanisms of Rupture surface formation and processes leading to slip weakening are not well defined. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large Earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by Earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during Earthquake Rupture.
Timothy E Dawson - One of the best experts on this subject based on the ideXlab platform.
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long term time dependent probabilities for the third uniform california Earthquake Rupture forecast ucerf3
Bulletin of the Seismological Society of America, 2015Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher Madden, David A Jackson, Andrew J MichaelAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP 2014) presents time-dependent Earthquake probabilities for the third Uniform California Earthquake Rupture Forecast (UCERF3). Building on the UCERF3 time-in- dependent model published previously, renewal models are utilized to represent elastic- rebound-implied probabilities. A new methodology has been developed that solves applicability issues in the previous approach for unsegmented models. The new meth- odology also supports magnitude-dependent aperiodicity and accounts for the historic open interval on faults that lack a date-of-last-event constraint. Epistemic uncertainties are represented with a logic tree, producing 5760 different forecasts. Results for a variety of evaluation metrics are presented, including logic-tree sensitivity analyses and comparisons to the previous model (UCERF2). For 30 yr M ! 6:7 probabilities, the most significant changes from UCERF2 are a threefold increase on the Calaveras fault and a threefold decrease on the San Jacinto fault. Such changes are due mostly to differences in the time-independent models (e.g., fault-slip rates), with relaxation of segmentation and inclusion of multifault Ruptures being particularly influential. In fact, some UCERF2 faults were simply too long to produce M 6.7 size events given the segmentation assumptions in that study. Probability model differences are also influential, with the implied gains (relative to a Poisson model) being generally higher in UCERF3. Accounting for the historic open interval is one reason. Another is an effective 27% increase in the total elastic-rebound-model weight. The exact factors influencing differences between UCERF2 and UCERF3, as well as the relative im- portance of logic-tree branches, vary throughout the region and depend on the evalu- ation metric of interest. For example, M ! 6:7 probabilities may not be a good proxy for other hazard or loss measures. This sensitivity, coupled with the approximate nature of the model and known limitations, means the applicability of UCERF3 should be evaluated on a case-by-case basis.
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uniform california Earthquake Rupture forecast version 3 ucerf3 the time independent model
Bulletin of the Seismological Society of America, 2014Co-Authors: Edward H Field, David D Jackson, Timothy E Dawson, Karen R Felzer, Thomas H Jordan, Ramon Arrowsmith, Glenn P Biasi, Peter Bird, Kaj M Johnson, Christopher MaddenAbstract:The 2014 Working Group on California Earthquake Probabilities (WGCEP14) present the time‐independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging Earthquakes in California. The primary achievements have been to relax fault segmentation and include multifault Ruptures, both limitations of UCERF2. The rates of all Earthquakes are solved for simultaneously and from a broader range of data, using a system‐level inversion that is both conceptually simple and extensible. The inverse problem is large and underdetermined, so a range of models is sampled using an efficient simulated annealing algorithm. The approach is more derivative than prescriptive (e.g., magnitude–frequency distributions are no longer assumed), so new analysis tools were developed for exploring solutions. Epistemic uncertainties were also accounted for using 1440 alternative logic‐tree branches, necessitating access to supercomputers. The most influential uncertainties include alternative deformation models (fault slip rates), a new smoothed seismicity algorithm, alternative values for the total rate of M w≥5 events, and different scaling relationships, virtually all of which are new. As a notable first, three deformation models are based on kinematically consistent inversions of geodetic and geologic data, also providing slip‐rate constraints on faults previously excluded due to lack of geologic data. The grand inversion constitutes a system‐level framework for testing hypotheses and balancing the influence of different experts. For example, we demonstrate serious challenges with the Gutenberg–Richter hypothesis for individual faults. UCERF3 is still an approximation of the system, however, and the range of models is limited (e.g., constrained to stay close to UCERF2). Nevertheless, UCERF3 removes the apparent UCERF2 overprediction of M 6.5–7 Earthquake rates and also includes types of multifault Ruptures seen in nature. Although UCERF3 fits the data better than UCERF2 overall, there may be areas that warrant further site‐specific investigation. Supporting products may be of general interest, and we list key assumptions and avenues for future model improvements.
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uniform california Earthquake Rupture forecast version 2 ucerf 2
Bulletin of the Seismological Society of America, 2009Co-Authors: Edward H Field, Timothy E Dawson, Karen R Felzer, Arthur Frankel, Vipin Gupta, Thomas H Jordan, Tom Parsons, Mark D Petersen, Ross S Stein, Ray J WeldonAbstract:The 2007 Working Group on California Earthquake Probabilities (WGCEP, 2007) presents the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2). This model comprises a time-independent (Poisson-process) Earthquake rate model, developed jointly with the National Seismic Hazard Mapping Program and a time-dependent Earthquake-probability model, based on recent Earthquake rates and stress-renewal statistics conditioned on the date of last event. The models were developed from updated statewide Earthquake catalogs and fault deformation databases using a uniform methodology across all regions and implemented in the modular, extensible Open Seismic Hazard Analysis framework. The rate model satisfies integrating measures of deformation across the plate-boundary zone and is consistent with historical seismicity data. An overprediction of Earthquake rates found at intermediate magnitudes (6.5≤ M ≤7.0) in previous models has been reduced to within the 95% confidence bounds of the historical Earthquake catalog. A logic tree with 480 branches represents the epistemic uncertainties of the full time-dependent model. The mean UCERF 2 time-dependent probability of one or more M ≥6.7 Earthquakes in the California region during the next 30 yr is 99.7%; this probability decreases to 46% for M ≥7.5 and to 4.5% for M ≥8.0. These probabilities do not include the Cascadia subduction zone, largely north of California, for which the estimated 30 yr, M ≥8.0 time-dependent probability is 10%. The M ≥6.7 probabilities on major strike-slip faults are consistent with the WGCEP (2003) study in the San Francisco Bay Area and the WGCEP (1995) study in southern California, except for significantly lower estimates along the San Jacinto and Elsinore faults, owing to provisions for larger multisegment Ruptures. Important model limitations are discussed.