Description: A new, largely revised and updated version of the Catalogue of Strong Earthquakes in Italy and in the Mediterranean area, termed CFTI5Med, was released in 2018 by Guidoboni et al. (https://doi.org/10.6092/ingv.it-cfti5). The Catalogue collects the results of over three decades of research in historical seismology in Italy and in the Mediterranean area. What makes CFTI5Med different from all other earthquake catalogues is that its database does not only contain parametric data and macroseismic intensities assigned to individual localities, but also textual descriptions of the territorial impact of each investigated earthquake sequence on both the built and the natural environment. For every investigated earthquake sequence, CFTI5Med supplies also the relevant bibliography in an organised form. Instrumental catalogues generally supply one record per earthquake. In contrast, the earthquake effects described by historical sources often refer to the combined effect of multiple shocks belonging to a sequence. For this reason, CFTI5Med presents the data organised "by earthquake sequence", after aggregating shocks that appear reasonably clustered in both time and space. For each investigated earthquake sequence we provide three different types of parametric information: 1) the full parameters of each shock of the sequence; 2) the intensity (according to the MCS scale) assigned to individual localities where each shock caused damage, or was felt, or was reported not felt; 3) a list of effects on the natural environment associated with a single shock (whenever possible) or with the entire sequence, subdivided into 32 different categories and assigned to individual localities. In addition, we supply the following synthetic summaries (in plain text form): • descriptions of the territorial impact and temporal evolution of the entire earthquake sequence; • descriptions of the effects on the built and natural environment for each individual locality.

Description: Historical earthquakes of the Gargano Promontory, an uplifted foreland sector in southeastern Italy, have been usually regarded as generated by inland faults. Some have been associated with activity of the Mattinata fault, a section of a regional east–west shear zone. The 10 August 1893 Mw 5.4 event is one such earthquake, but its current onshore location is only loosely based on the damage pattern.Regions that were hit by offshore earthquakes are also known to be affected by a methodological bias such that offshore historical events appear to be located onshore. To test this condition for the 1893 earthquake, we pursued an alternative hypothesis for its location. The earthquake occurred near the Gondola fault zone, a right-lateral active fault system representing the offshore counterpart of the Mattinata fault and hence capable of producing sizable earthquakes along the Gargano coast. We focused on its westernmost segment, suggesting that it could be the causative fault of the 1893 earthquake (in agreement with both the damage distribution and reported environmental effects).The approach we present works side by side with the recent developments of the algorithms used to compile historical catalogs, providing a fine-scale, geologically based method to define or confirm the dubious location of historical earthquakes. Marine paleoseismology is a new field stemming from the increased capabilities of high-resolution marine techniques in supporting classical paleoseismological analyses for the exploration of the seismogenic potential of offshore faults. Based on Late Pleistocene and Holocene individual or cumulative earthquake records, the potential of offshore faults can now be constrained in terms of expected magnitude and recurrence intervals.We stress the importance of revisiting historical earthquakes in coastal zones using marine paleoseismological data to assess regional seismic hazard, particularly in tectonic settings where regional-size seismogenic areas straddle the onshore and the onshore–offshore zone.

Description: We investigated whether the joint inversion of geodetic and stress direction data can constrain long‐term fault slip rates in the central Apennines, and ultimately how extension is partitioned among fault slip and bulk lithosphere permanent strain. Geodetic velocities are collected in the fault interseismic stage with steady secular deformation; thus, long‐term estimates can be derived with a model of elastically unloading seismogenic faults within a viscously deforming lithosphere. As the average spacing of permanent Global Navigation Satellite Systems (GNSS) stations is similar to the average length of seismogenic faults (25–35 km), if not larger, we decided to merge permanent and temporary GNSS measurements, resulting in a denser geodetic data set. Given that most normal faults in the Apennines have slip rates around or below 1 mm/a, and most campaign GNSS velocities carry similar uncertainties, simple local back slip models cannot be applied. More sophisticated modeling is required to extract reasonable bulk deformation rates and long‐term fault slip rates at signal‐to‐noise ratio of order unity. Given the spatial distribution of the GNSS network, we estimated the long‐term slip rate of seven major fault systems that are in satisfactory agreement with available geological slip rates. The resulting spatial distribution of bulk deformation rates locally fits short‐term transients; in other cases, they represent the currently unclear signature of tectonic processes like upper‐crustal viscoplastic deformation and aseismic slip, or indicate missing faults in the adopted database. We conclude that the time is ripe for determining fault slip rates using geodetic and stress direction data, particularly where fault activity rates are hard to determine geologically.

Description: Published

Description: e2019JB018956

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: There is growing interest in how geofluid emissions are released in the atmosphere by the planet’s geodynamic activity, and how much they contribute to the global budget of greenhouse gases. Many workers are addressing this issue with studies conducted at global scale, so as to get the required global-scale answers. The data available at the global scale on geofluids, faults, earthquakes and volcanoes, however, are generally too coarse to provide these answers. We investigate the relationships between geofluid emissions and tectonics at a more detailed scale. Building on over a century of data on geofluid emissions and on an extensive knowledge of the region’s tectonics and seismicity, we focused on Italy, one of the areas of the globe that experience the largest release of natural CO2 and CH4. We systematically overlaid and compared data collected by a number of workers into 13 published countrywide databases concerning geofluid emissions, carbonbearing deposits, seismogenic faults, historical and instrumentally documented earthquakes, and heat flow observations. Our results indicate that 1) thermal springs and CO2 emissions dominate in areas of mantle upwelling and crustal stretching, but also that 2) some of them occur in the extending inner Apennines, generally along major lithospheric chain-perpendicular lineaments that bound the largest normal faults. Conversely, 3) CH4 emissions and mud volcanoes dominate in areas undergoing active contraction, where no CO2 emissions are observed; in particular, we find 4) that mud volcanoes concentrate where the crests of active anticlines intersect major lithospheric chain-perpendicular lineaments. An overarching conclusion is that, in Italy, the release of geofluids is primarily controlled by deep crustal discontinuities that developed over the course of 5–10 My, and is only mildly affected by ongoing crustal strains. Geofluid emissions bring information on processes that occur primarily in the lower crust, marking the surface projection of generally hidden discontinuities that control the geometry and modes of seismic release. As such they may also provide valuable insight for improving the assessment of seismic hazard in hard-to-investigate seismically active regions, such as Italy.

Description: Published

Description: 579390

Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici

Description: JCR Journal