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This article focuses on the Montello thrust system in the Eastern Southern Alps as a potential seismogenic source. This system is of particular interest because of its lack of historical seismicity. Nevertheless, the system is undergoing active deformation. We developed a finite‐element model using visco‐elasto‐plastic rheology. The free parameters of the model (essentially, the locking status of the three thrusts included in the study), were constrained by matching the observed horizontal GPS and vertical levelling data. We show that the amount of interseismic fault locking, and thus the seismic potential, is not necessarily associated with the fastest‐slipping faults. More specifically, the locked Bassano thrust has a greater seismic potential than the freely slipping Montello thrust. The findings suggest that faults with subtle evidence of Quaternary activity should be carefully considered when creating seismic hazard maps. 相似文献
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Paola?VannoliEmail author Pierfrancesco?Burrato Gianluca?Valensise 《Pure and Applied Geophysics》2015,172(5):1105-1142
We present a systematic and updated overview of a seismotectonic model for the Po Plain (northern Italy). This flat and apparently quiet tectonic domain is, in fact, rather active as it comprises the shortened foreland and foredeep of both the Southern Alps and the Northern Apennines. Assessing its seismic hazard is crucial due to the concentration of population, industrial activities, and critical infrastructures, but it is also complicated because (a) the region is geologically very diverse, and (b) nearly all potential seismogenic faults are buried beneath a thick blanket of Pliocene–Pleistocene sediments, and thus can be investigated only indirectly. Identifying and parameterizing the potential seismogenic faults of the Po Plain requires proper consideration of their depth, geometry, kinematics, earthquake potential and location with respect to the two confronting orogens. To this end, we subdivided them into four main, homogeneous groups. Over the past 15 years we developed new strategies for coping with this diversity, resorting to different data and modeling approaches as required by each individual fault group. The most significant faults occur beneath the thrust fronts of the Ferrara-Romagna and Emilia arcs, which correspond to the most advanced and buried portions of the Northern Apennines and were the locus of the destructive May 2012 earthquake sequence. The largest known Po Plain earthquake, however, occurred on an elusive reactivated fault cutting the Alpine foreland south of Verona. Significant earthquakes are expected to be generated also by a set of transverse structures segmenting the thrust system, and by the deeper ramps of the Apennines thrusts. The new dataset is intended to be included in the next version of the Database of Individual Seismogenic Sources (DISS; http://diss.rm.ingv.it/diss/, version 3.2.0, developed and maintained by INGV) to improve completeness of potential sources for seismic hazard assessment. 相似文献
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Pierfrancesco Burrato Maria Eliana Poli Paola Vannoli Adriano Zanferrari Roberto Basili Fabrizio Galadini 《Tectonophysics》2008,453(1-4):157
We present an overview of the seismogenic sources of northeastern Italy and western Slovenia, included in the last version of the Database of Individual Seismogenic Sources (DISS 3.0.2) and a new definition of the geometry of the Montello Source that will be included in the next release of the database. The seismogenic sources included in DISS are active faults capable of generating Mw > 5.5 earthquakes. We describe the method and the data used for their identification and characterization, discuss some implications for the seismic hazard and underline controversial points and open issues.In the Veneto–Friuli area (NE Italy), destructive earthquakes up to Mw 6.6 are generated by thrust faulting along N-dipping structures of the Eastern Southalpine Chain. Thrusting along the mountain front responds to about 2 mm/a of regional convergence, and it is associated with growing anticlines, tilted and uplifted Quaternary palaeolandsurfaces and forced drainage anomalies. In western Slovenia, dextral strike–slip faulting along the NW–SE trending structures of the Idrija Fault System dominates the seismic release. Activity and style of faulting are defined by recent earthquakes (e.g. the Ms 5.7, 1998 Bovec–Krn Mt. and the Mw 5.2, 2004 Kobarid earthquakes), while the related recent morphotectonic imprint is still a debated matter.We reinterpreted a large set of tectonic data and developed a segmentation model for the outermost Eastern Southalpine Chain thrust front. We also proposed the association of the four major shocks of the 1976 Friuli earthquake sequence with individual segments of three major thrust fronts. Although several sub-parallel active strike–slip strands exist in western Slovenia, we were able to positively identify only two segments of the Idrija Fault System. A comparison of the regional GPS velocity with long-term geological slip-rates of the seismogenic sources included in DISS shows that from a quarter to half of the deformation is absorbed along the external alignment of thrust faults in Veneto and western Friuli. The partitioning of the deformation in western Slovenia among the different strike–slip strands could not be quantified. 相似文献
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Daniela Di Bucci Paola Vannoli Pierfrancesco Burrato Umberto Fracassi Gianluca Valensise 《地学学报》2011,23(6):421-423
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1783年2~3月期间卡拉布里亚南部发生了5次大地震。大部分学者认为该次地震发震断层西倾、断层倾角较陡,断层在位于平原ESE部地区的结晶基岩上发生错动(Aspromonte断层)。而另外一些学者则认为发震断层为东倾且倾角较缓的隐伏断层(G ioia Tauro断层),和与其相邻的墨西拿海峡断裂相似。为了寻找发震断层方面的证据,1999—2000年期间,我们在G ioia Tauro平原共开展了4次地球化学调查。调查的目的是通过识别断层作用(或破裂),加强和深部水文循环有关的地球化学异常,得到关于地震成因方面的新的认识。深部流体特征用温度、盐度、碳总量与氡异常表征。共划分出三个主要的深部流体释放带:N icotera-Galatro地区(沿着NW向N icotera-G ioiosa-Jonica区域断裂线的N icotera-Galatro段);G ioia-Tauro与Sem inara之间的NW-SE向小区域及Rosarno与Palm i之间的海岸线。其中Rosarno与Palm i之间的海岸线正好位于推测的G ioia Tauro断层上界。绝大部分地球化学异常发生在Rosarno周围,该地区位于G ioiaTauro断层与N icotera-G ioiosa-Jonica区域断裂线的交汇部位。而在Aspromonte断层带没有发生明显的地下水侵蚀和压裂。基于以上发现我们提出了地球化学活动断裂带和地球化学交互作用断裂带的概念,从而进一步认识断层带的水力学特征及地壳中促使裂隙渗透性增强的断层作用机制。 相似文献
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F. Cultrera G. Barreca P. Burrato L. Ferranti C. Monaco S. Passaro F. Pepe L. Scarfì 《Natural Hazards》2017,86(2):253-272
The Gulf of Patti and its onshore sector represent one of the most seismically active regions of the Italian Peninsula. Over the period 1984–2014, about 1800 earthquakes with small-to-moderate magnitude and a maximum hypocentral depth of 40 km occurred in this area. Historical catalogues reveal that the same area was affected by several strong earthquakes such as the Mw = 6.1 event in April 1978 and the Mw = 6.2 one in March 1786 which have caused severe damages in the surrounding localities. The main seismotectonic feature affecting this area is represented by a NNW–SSE trending right-lateral strike-slip fault system called “Aeolian–Tindari–Letojanni” (ATLFS) which has been interpreted as a lithospheric transfer zone extending from the Aeolian Islands to the Ionian coast of Sicily. Although the large-scale role of the ATLFS is widely accepted, several issues about its structural architecture (i.e. distribution, attitude and slip of fault segments) and the active deformation pattern are poorly constrained, particularly in the offshore. An integrated analysis of field structural geology with marine geophysical and seismological data has allowed to better understand the structural fabric of the ATLFS which, in the study area, is expressed by two major NW–SE trending, en-echelon arranged fault segments. Minor NNE–SSW oriented extensional structures mainly occur in the overlap region between major faults, forming a dilatational stepover. Most faults display evidence of active deformation and appear to control the main morphobathymetric features. This aspect, together with diffused continental slope instability, must be considered for the revaluation of the seismic and geomorphological hazard of this sector of southern Tyrrhenian Sea. 相似文献
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Cultrera F. Barreca G. Burrato P. Ferranti L. Monaco C. Passaro S. Pepe F. Scarf&#; L. 《Natural Hazards》2016,86(2):253-272
The Gulf of Patti and its onshore sector represent one of the most seismically active regions of the Italian Peninsula. Over the period 1984–2014, about 1800 earthquakes with small-to-moderate magnitude and a maximum hypocentral depth of 40 km occurred in this area. Historical catalogues reveal that the same area was affected by several strong earthquakes such as the Mw = 6.1 event in April 1978 and the Mw = 6.2 one in March 1786 which have caused severe damages in the surrounding localities. The main seismotectonic feature affecting this area is represented by a NNW–SSE trending right-lateral strike-slip fault system called “Aeolian–Tindari–Letojanni” (ATLFS) which has been interpreted as a lithospheric transfer zone extending from the Aeolian Islands to the Ionian coast of Sicily. Although the large-scale role of the ATLFS is widely accepted, several issues about its structural architecture (i.e. distribution, attitude and slip of fault segments) and the active deformation pattern are poorly constrained, particularly in the offshore. An integrated analysis of field structural geology with marine geophysical and seismological data has allowed to better understand the structural fabric of the ATLFS which, in the study area, is expressed by two major NW–SE trending, en-echelon arranged fault segments. Minor NNE–SSW oriented extensional structures mainly occur in the overlap region between major faults, forming a dilatational stepover. Most faults display evidence of active deformation and appear to control the main morphobathymetric features. This aspect, together with diffused continental slope instability, must be considered for the revaluation of the seismic and geomorphological hazard of this sector of southern Tyrrhenian Sea.
相似文献9.
Five large earthquakes shook southern Calabria in February–March 1783. We focused on the first shock (Me 6.9), which occurred on 5 February in the Gioia Tauro Plain. Most investigators attribute the event to a W-dipping, high-angle fault running at the base of the Aspromonte crystalline bedrock on the ESE side of the Plain (Aspromonte Fault). Other workers contend that the earthquake was generated by an E-dipping, low-angle blind fault (Gioia Tauro Fault) similar to the adjacent Messina Straits Fault. In 1999–2000 we carried out four geochemical surveys in the Gioia Tauro Plain with the aim of contributing to this debate with an independent line of evidence. We sampled 240 groundwater sites and measured a suite of in-situ physical and chemical parameters. Our goal was to gain new insight into the seismogenic source by identifying geochemical anomalies associated with the deepening of the hydrological circuits due to the presence of enhanced faulting/fracturing. The deep-fluid signatures are mainly represented by temperature, salinity, total carbon and radon anomalies. We identified three zones of dominant deep fluid discharge: the Nicotera-Galatro area (along the Nicotera-Galatro portion of the NW-trending Nicotera-Gioiosa Jonica lineament), a small NW-SE trending area between Gioia Tauro and Seminara, and the coastline between Rosarno and Palmi. This latter sector locates just above the upper edge of the hypothesised Gioia Tauro Fault. Most of the geochemical anomalies are recorded around Rosarno, at the intersection between the Gioia Tauro Fault and the Nicotera-Gioiosa Jonica lineament. In contrast, no evidence of groundwater deepening and active fracturing was found along the Aspromonte Fault. Based on our new findings we updated the concepts of Geochemically Active Fault Zone and Geochemical Interaction Fault Zone in view of the modern understanding of the hydro-mechanical properties of fault zones and the faulting mechanisms promoting fracture permeability in the crust. 相似文献
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