Fault displacement hazard assessment is based on empirical relationships that are established using historic earthquake fault ruptures. These relationships evaluate the likelihood of coseismic surface slip considering on‐fault and off‐fault ruptures, for given earthquake magnitude and distance to fault. Moreover, they allow predicting the amount of fault slip at and close to the active fault of concern. Applications of this approach include land use planning, structural design of infrastructure, and critical facilities located on or close to an active fault. To date, the current equations are based on sparsely populated datasets, including a limited number of pre‐2000 events. In 2015, an international effort started to constitute a worldwide and unified fault displacement database (SUrface Ruptures due to Earthquakes [SURE]) to improve further hazard estimations. After two workshops, it was decided to unify the existing datasets (field‐based slip measurements) to incorporate recent and future cases, and to include new parameters relevant to properly describe the rupture. This contribution presents the status of the SURE database and delineates some perspectives to improve the surface‐faulting assessment. Original data have been compiled and adapted to the structure. The database encompasses 45 earthquakes from magnitude 5–7.9, with more than 15,000 coseismic surface deformation observations (including slip measurements) and 56,000 of rupture segments. Twenty earthquake cases are from Japan, 15 from United States, two from Mexico, Italy, and New Zealand, one from Kyrgystan, Ecuador, Turkey, and Argentina. Twenty‐four earthquakes are strike‐slip faulting events, 11 are normal or normal oblique, and 10 are reverse faulting. To pursue the momentum, the initial and common implementation effort needs to be continued and coordinated, and the maintenance and longevity of the database must be guaranteed. This effort must remain based on a large and open community of earthquake geologists to create a free and open access database.
Surface rupturing data from the historical earthquakes is used for obtaining empirical regression parameters for fault displacement hazard assessment. This paper represents an additional compilation and analysis effort, extending the first version of the SUrface Ruptures due to Earthquake (SURE) database. This new release contains slip measurements and mapped surface rupture traces of 50 surface rupturing earthquakes of reverse, normal, and strike-slip kinematics occurred all over the world between 1872 and 2019. As a novelty, a ranking scheme of the rupture features is applied to all the traces and slip measurements in the database. Fault ranking introduces geology as a primary analysis tool and allows the end user to obtain regression parameters suitable for the specific geological conditions at the site of interest. SURE 2.0 dataset consists of a table containing the background information about each earthquake, a table containing the slip measurement data of each event, and a joint shapefile containing all the surface rupture traces of the events in the database.
<p>Probabilistic fault displacement hazard analysis (PFDHA) is needed for a numerical estimate of the displacement likely to occur at a site near an active fault in case of a surface faulting earthquake. The methodology is based on parameters describing the probability of occurrence, and the spatial distribution of the displacement on and off-fault. The methodology was created for normal faulting setting, and has been later complemented with the parameters for other slip types, especially regarding the principal fault rupturing. Based on empirical fault displacement data in the Worldwide and Unified Database of Surface Ruptures (SURE), we are presenting new regression parameters for distributed faulting for dip-slip earthquakes. The parameters are used in a computational model for assessing the surface rupture hazard near active dip-slip faults. The modelling results the probability distribution of exceeding a chosen level of displacement, and can be used in stcture design and land-use related decision making in areas where surface faulting hazard should be considered.</p>
<p>Probabilistic fault displacement hazard analysis (PFDHA) estimates the probability of occurrence and the expected exceedance of on-fault (principal fault rupturing; PF) and off-fault (dist ributed rupturing; DR) surface displacement during an earthquake. Here we concent rate on off-fault rupturing on dip-slip earthquakes, and present an original probability model for the occurrence of DR and for the expected exceedance of displacement dist ribution based on an approach named &#8220;slicing&#8221; (an alternative to the &#8220;gridding&#8221; approach commonly used). The method is developed based on the compilation and reappraisal of surface ruptures from 32 historical crustal dip-slip earthquakes, with magnitudes ranging from M<sub>w</sub> 4.9 to 7.9. A ranking scheme is applied to distinguish PF (rank 1) from simple DR (rank 2) and t riggered faulting (rank 3). Thus modellers can use prediction equations based on or excluding ruptures st rongly related to local st ructural setting depending on the site of concern. In the case of a st ructural setting at a site where large-scale bending (rank 21, 22) and pre-existing faults (rank 1.5, 3) is considered irrelevant, modelling can be performed considering only the unpredictable DR (rank 2). To minimize bias due to the incomplete nature of the database, we int roduce the &#8220;slicing&#8221; approach, which considers that the probability of having a surface rupture within slices parallel to the PF is homogeneous along the st rike of each slice. &#8220;Slicing&#8221; probabilities, computed as a function of magnitude of the earthquake and distance from the PF, are then combined with Monte Carlo simulations that model the dependence of the probability of occurrence of rupture and exceedance of displacement with the dimensions and position of the site of interest with respect to the PF. Finally, both probabilities are combined with existing predictive equations of exceedance of displacement on the PF to calculate fault-displacement hazard curves for sites of interest.</p>
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