We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting.

The multisegment Wasatch fault zone is a well-studied normal fault in the western United States that has paleoseismic evidence of recurrent Holocene surface-faulting earthquakes. Along the 270 km long central part of the fault, four primary structural complexities provide possible along-strike limits to these ruptures and form the basis for models of fault segmentation. Here, we assess the impact that the Wasatch fault segmentation model has on seismic hazard by evaluating the time-independent long-term rate of ruptures on the fault that satisfy fault-slip rates and paleoseismic event rates, adapting standard inverse theory used in the Uniform California Earthquake Rupture Forecast, Version 3, and implementing a segmentation constraint in which ruptures across primary structural complexities are penalized. We define three models with varying degrees of rupture penalization: (1) segmented (ruptures confined to individual segments), (2) penalized (multisegment ruptures allowed, but penalized), and (3) unsegmented (all ruptures allowed). Seismic-hazard results show that, on average, hazard is highest for the segmented model, in which seismic moment is accommodated by frequent moderate (moment magnitude Mw 6.2–6.8) earthquakes. The unsegmented model yields the lowest average seismic hazard because part of the seismic moment is accommodated by large (Mw 6.9–7.9) but infrequent ruptures. We compare these results to model differences derived from other inputs such as slip rate and magnitude scaling relations and conclude that segmentation exerts a primary control on seismic hazard. This study demonstrates the need for additional geologic constraints on rupture extent and methods by which these observations can be included in hazard-modeling efforts.

This work focuses on how the progress in earthquake science that follows a large, deeply studied earthquake might be promptly combined with updated approaches of seismic hazard analysis to guide applicative choices for seismic risk reduction, such as postevent seismic microzoning and building design. Both seismic microzoning and seismic design of structures require strong motion records to perform numerical site response analyses. These records have to be related to the seismotectonic context and historical seismicity of the investigation area. We first performed a fault-based probabilistic seismic hazard analysis in the area struck by the 2016 central Italy seismic sequence to individuate reference uniform hazard spectra at rock conditions. We used two different seismic hazard models, one considering 27 individual seismogenic sources (ISSs), and the second one involving grid point seismicity, using a fixed-radius smoothing approach. The geological and seismotectonic data of the 2016 seismic sequence were used to update the model of ISSs. We performed a deaggregation analysis to evaluate the contribution of the ISS in the hazard of four representative sites and to select the magnitude-distance pairs useful in the selection of the real accelerograms. The deaggregation analysis has been performed to identify which source and magnitude most contribute to the hazard for each site, and for different periods of spectral accelerations. Finally, we select, for each site, a set of natural accelerograms, from both nonimpulsive and pulse-like records, based on the magnitude-distance pairs that are compatible on average with target uniform hazard spectra.

Automated temporal planning is the technology of choice when controlling systems that can execute more actions in parallel and when temporal constraints, such as deadlines, are needed in the model. One limitation of several action-based planning systems is that actions are modeled as intervals having conditions and effects only at the extremes and as invariants, but no conditions nor effects can be specified at arbitrary points or sub-intervals.In this paper, we address this limitation by providing an effective heuristic-search technique for temporal planning, allowing the definition of actions with conditions and effects at any arbitrary time within the action duration. We experimentally demonstrate that our approach is far better than standard encodings in PDDL 2.1 and is competitive with other approaches that can (directly or indirectly) represent intermediate action conditions or effects.

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