Variability of Displacement at a Point: Implications for Earthquake-Size Distribution and Rupture Hazard on Faults

Hecker, Suzanne; Abrahamson, Norman A.; Wooddell, K. E.

doi:10.1785/0120120159

Cited by 71 publications

(64 citation statements)

References 49 publications

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“…However, this option is given zero weight for the same reasons it was excluded in UCERF2-lack of observational support and implications that some ruptures cannot happen. There is some evidence to support a characteristic slip model in which the amount of slip on a subsection is similar for all ruptures (Hecker et al, 2013), but applying this would be difficult because of very limited observational constraints, which would require the propagation of large epistemic uncertainties that have unknown spatial correlations. Instead, we compare the slip-per-event implications of UCERF3 with the results from Hecker et al (2013).…”

Section: Slip Rate Balancing (Equation Set 1) Equation Set (1) Ofmentioning

confidence: 99%

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Field

Arrowsmith

Biasi

et al. 2014

Bulletin of the Seismological Society of America

518

467

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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. Manuscript OrganizationBecause of manuscript length and model complexity, we begin with an outline of this report to help readers navigate the various sections:

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Section: Slip Rate Balancing (Equation Set 1) Equation Set (1) Ofmentioning

confidence: 99%

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Field

Arrowsmith

Biasi

et al. 2014

Bulletin of the Seismological Society of America

518

467

View full text Add to dashboard Cite

show abstract

“…In order to implement this approach, the geometries and slip rates of the faults have to be known within uncertainties, FtF rupture scenarios sets have to be defined, and the shape of the regional MFD needs to be assumed or inferred from the regional catalog. If for the WCR the GR distribution seems suitable, it has been shown that a Youngs and Coppersmith distribution (Youngs and Coppersmith, 1985) can be more appropriate for other fault systems (e.g., by Hecker et al, 2013). Given the flexibility of our methodology any other target MFD can be easily implemented in the methodology.…”

Section: Discussionmentioning

confidence: 99%

Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

Chartier

Scotti

Lyon‐Caen

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. Modeling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (fault-to-fault, FtF, ruptures). The Uniform California Earthquake Rupture Forecast version 3 (UCERF-3) model takes into account this possibility by considering a system-level approach rather than an individual-fault-level approach using the geological, seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information along fault networks is often not well constrained. There is therefore a need to propose a methodology relying on geological information alone to compute earthquake rates of the faults in the network. In the proposed methodology, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty, similarly to UCERF-3. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an a priori chosen shape and the rate of earthquakes on each fault is determined by the specific slip rate of each segment depending on the possible FtF ruptures. The modeled earthquake rates are then compared to the available independent data (geodetical, seismological and paleoseismological data) in order to weight different hypothesis explored in a logic tree.The methodology is tested on the western Corinth rift (WCR), Greece, where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ∼ 15 mm yr −1 north-south extension. Modeling results show that geological, seismological and paleoseismological rates of earthquakes cannot be reconciled with only singlefault-rupture scenarios and require hypothesizing a large spectrum of possible FtF rupture sets. In order to fit the imposed regional Gutenberg-Richter (GR) MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, computed individual faults' MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modeled earthquake rupture rates with those deduced from the regional and local earthquake catalog statistics and local paleoseismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on 5 km rather than 3 km, suggesting a high connectivity of faults in the WCR fault system.

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“…Faults that have had multiple surface ruptures in historic time generally rupture in a similar fashion, along the same fault trace (Hecker et al, 2013). In addition, in a complex fault zone, surface ruptures are generally observed to occur along the youngest fault traces.…”

Section: Surface Fault Rupture Behaviourmentioning

confidence: 99%

Characterisation of Surface Fault Rupture for Civil Engineering Design

Fenton

Kernohan

2014

Engineering Geology for Society and Territory - Volume 5

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Lifelines crossing active faults are vulnerable to damage during surface faulting earthquakes. The design of mitigation measures requires detailed knowledge of fault location, rupture zone width, and the distribution of strain within the fault zone. Although the general magnitude of surface ruptures can be characterised by empirical relationships, behaviour at a specific location is harder to forecast. To understand displacement distribution within the damage zone we need to examine historical surface ruptures. Recent earthquakes (e.g., Wenchuan, 2008; Darfield 2010) provide the opportunity to study the effects of fault geometry, near surface materials and along-strike location on the damage zone width and strain distribution, allowing the development of preliminary empirical models for surface rupture characterisation. As well as presenting these models this paper evaluates current fault investigation practice and describes an alternative approach to defining potential surface rupture zones using existing geologic data, providing a cost-effective, reasonable and rational basis for characterising site-specific rupture hazard.

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Variability of Displacement at a Point: Implications for Earthquake-Size Distribution and Rupture Hazard on Faults

Cited by 71 publications

References 49 publications

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Methodology for earthquake rupture rate estimates of fault networks: example for the western Corinth rift, Greece

Characterisation of Surface Fault Rupture for Civil Engineering Design

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