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We describe a set of seismological observations of the foreshock sequence preceding the 6 April 2009 [M.sub.w] 6.3 L'Aquila earthquake. The dense configuration of the seismic network in the epicenter area and the occurrence of a long foreshock sequence provide the opportunity for a detailed reconstruction of the preparatory phase of the main shock. Approaching the earthquake, we observed clear variations in the seismic wave propagation properties. The elastic properties of rocks in the fault region underwent a sharp change about a week before the earthquake. From our observations, we infer that a complex sequence of dilatancy-diffusion processes takes place and that fluids play a key role in the fault failure process. doi: 10.1130/G31463.1

We apply a new analysis technique using earthquake focal mechanisms to infer the 3-D fluid pressure field at depth in the source region of the A.D. 2009 L'Aquila earthquake/aftershock sequence. The technique, termed focal mechanism tomography, inverts for fluid pressure by examining the fault orientation relative to the regional tectonic stress pattern. We identify three large-scale pockets of high fluid pressure (up to 50 MPa above hydrostatic pressure) at depths of 7-10 km that strongly correlates with an independent data set of well-located foreshocks and aftershocks. The shape of overpressured regions and the evolution of seismicity indicate a plausible scenario that this sequence is being driven in part by the poro-elastic response of trapped reservoirs of high-pressure fluid, presumably C[O.sub.2], and postseismic fluid flow initiated by the main shock. doi: 10.1130/G31457.1

[1] We investigate the seismic structure of the [M.sub.w]5.7, 2002 Molise earthquake area in order to understand the role of E-W trending strike-slip faults in the tectonics of the southern Apennines. We apply an innovative seismic migration technique to a high quality data set of earthquakes recorded at a dense local network. SP-converted waves are migrated in depth to image the high impedance contrast of the Apulian Platform top buried under the Apennines allochthonous cover. The continuity of the migrated seismic horizon is broken by vertical steps that we systematically picked along 200 cross sections. The best location points of these structures define two main tectonic features. The first one is related to NW-SE oriented normal faults and is consistent with the SW flexure of the foreland lithosphere beneath the orogenic belt. The second one indicates that shallow E W oriented trans-tensional faults are concentrated directly above the deeper (10-20 km) strike-slip fault, delineating the geometry of a negative flower-type structure. This fault system delimits a depressed sector of the Apulian Platform, whose geometry is consistent with a pull-apart basin inherited from a previous left-lateral strike-slip tectonic regime. The buried structure is analogous to those outcropping in the Apulian foreland and in the Adriatic offshore, to the east. This correlation brings new support to the hypothesis of a regional E W trending shear zone cutting the Adria plate and suggests that other earthquakes could occur on this or on parallel E-W trending strike-slip faults. Citation: Latorre, D., A. Amato, and C. Chiarabba (2010), High-resolution seismic imaging of the [M.sub.w]5.7, 2002 Molise, southern Italy, earthquake area: Evidence of deep fault reactivation, Tectonics, 29, TC4014, doi: 10.1029/2009TC002595.

The study shows that exemption of boys in compulsory military service (CMS) after a 1980 earthquake in Italy led to a 2% increase in male high school graduation rate. The rise in graduation rate was due to earthquake-related CMS exemption and not other factors. Comparison with female graduation rates and details on peer effects are also discussed.

Relay ramps commonly occur in areas of active extension. They have relevance in terms of fault segmentation, fault linkage, and related seismic potential. We propose consideration of field evidence of an active relay ramp in a seismic area as a clue to the definition of a seismogenic normal fault. We have chosen the Calore River valley as our study area. it is located within the core of the Apennine chain of the Italian Peninsula and is characterized by active extension and associated severe seismicity, in particular, a destructive earthquake struck the study area in 1688. We integrated data deriving from a geological field survey with original geomorphic and mesostructural analyses and new radiometric dating ([sup.40]Ar/[sup.39]Ar). Results indicate that brittle deformation detected in the northern part of Mt. Camposauro could represent the surface expression of the NE-dipping main fault of an active extensional system we refer to as the Calore River fault system. Its structural connection with the neighboring Boiano Basin extensional fault system is marked by an area of complex deformation, which links them and can be described as a stage 3 relay ramp. Given that the Boiano Basin fault system is a seismogenic source, the identification of a relay ramp implies a seismogenic role also for the Calore River fault system. In turn, these results allow us to suggest a new hypothesis for the seismogenic source of the 1688 Sannio earthquake. Finally, we discuss the implications on the seismic potential of two seismogenic structures linked by a relay ramp. Keywords: transfer zone, fault interaction, seismogenic fault system, Benevento, southern Apennines.

The Italian territory has been the object of several studies devoted to the analysis of seismicity and to earthquake precursors' research. Although a number of observations have been claimed to precede large earthquakes, only few systematic studies have been carried out and almost no test of their performances is available up to now. In this paper, we review the application to the Italian territory of two formally defined intermediate-term middle-range earthquake prediction algorithms, namely CN and M8S. The general methodology common to the two different algorithms makes use of general concepts of pattern recognition that permit to deal with multiple sets of seismic precursors, and allows for a systematic monitoring of seismicity, as well as for a widespread testing of the prediction performances. Italy represents the only region of moderate seismic activity where the MSS and CN algorithms are applied simultaneously for routine monitoring. Significant efforts have been made to minimize the intrinsic space uncertainty of predictions and the subjectivity of the definition of the areas where precursors should be identified. Several experiments have been dedicated to assess the robustness of the methodology against the unavoidable uncertainties in the data. With these results acquired; starting in July 2003, an experiment was launched for the real-time test of M8S and CN predictions. Kevwords: Earthquake prediction; Pattern recognition; Prediction algorithms; Seismicity and seismotectonics; Italy

A seismically active low-angle normal fault is recognized at depth in the Northern Apennines, Italy, where recent exhumation has also exposed ancient examples at the surface, notably the Zuccale fault on Elba. Field-based and microstructural studies of the Zuccale fault reveal that an initial phase of pervasive cataclasis increased fault zone permeability, promoting influx of C[0.sub.2]-rich hydrous fluids. This triggered low-grade alteration and the onset of stress-induced dissolution precipitation processes (e.g. pressure solution) as the dominant grain-scale deformation process in the pre-existing cataclasites leading to shear localization and the formation of a narrow foliated fault core dominated by fine-grained hydrous mineral phases. These rocks exhibit ductile deformation textures very similar to those formed during pressure-solution-accommodated 'frictional-viscous' creep in experimental fault rock analogues. The presence of multiple hydrofracture sets also points to the local attainment of fluid overpressures following development of the foliated fault core, which significantly enhanced the sealing capacity of the fault zone. A slip model for low-angle normal faults in the Apennines is proposed in which aseismic frictional-viscous creep occurs on a weak, slow-moving (slip rate Keywords: Zuccale fault, Northern Apennines, normal faults, earthquakes, rheology.

The Sannio earthquake is one of the numerous tremors felt and recorded in Italy over last many years but very few details are known due to unknown fault systems and lack of concrete proofs. The geologists are conducting studies in the Apennines based on unexplored geologic structures to discover the complex fault system underlying the area that would help the planners to prepare for future seismic events.

Geologists have found a still-active fault stretching for 200 kilometers beneath the Adriatic Sea and connecting at its southern end to a seismically active zone responsible for several earthquakes in ancient times.