Cari Colleghi e Amici,
siamo lieti di annunciare che il 6th INQUA International Workshop sulla Tettonica attiva, Paleosismologia e Archeosismologia si terrà a Pescina (AQ) nel periodo 19-24 Aprile 2015. Nell’ambito dell’evento scientifico si celebrerà il Centenario del terremoto del Fucino 1915.
Seguiranno aggiornamenti sull’evento.
Avanzamento delle conoscenze geologiche sulla faglia responsabile del terremoto di L'Aquila del 2009
SOLIDARIETÀ AI NOSTRI COLLEGHI SISMOLOGI CONDANNATI IN PRIMO GRADO
Noi lavoratori dell'Istituto Nazionale di Geofisica e Vulcanologia esprimiamo piena solidarietà al nostro collega Giulio Selvaggi (ricercatore INGV e Direttore del Centro Nazionale Terremoti nel 2009) e al Prof. Enzo Boschi (allora Presidente dell'INGV), entrambi condannati per la loro attività di consulenza tecnico-scientifica al servizio dello Stato. La sentenza colpisce loro ma allo stesso tempo anche noi e il lavoro che svolgiamo nel nostro ente pubblico di ricerca a beneficio della collettività, e che loro hanno rappresentato alla riunione della Commissione.
Comunicato sulle motivazioni della sentenza de l'Aquila 18 gennaio 2013
Press Release on the reasons for the L'Aquila verdict - January 18, 2013
Comunicato sulla sentenza del processo a L'Aquila
Press release on the conviction at the L'Aquila trial, English version
Documenti, articoli e lettere della comunità scientifica riguardanti il processo
Documents, articles and letters from the scientific community about the trial
Rilievi geologici del terremoto emiliano da parte del gruppo Emergeo
Ups and downs in western Crete (Hellenic subduction zone)
Mara Monica Tiberti, Roberto Basili, Paola Vannoli
Scientific Reports, 4, 5677, doi:10.1038/srep05677.
Studies of past sea-level markers are commonly used to unveil the tectonic history and seismic behavior of subduction zones. We present new evidence on vertical motions of the Hellenic subduction zone as resulting from a suite of Late Pleistocene - Holocene shorelines in western Crete (Greece). Shoreline ages obtained by AMS radiocarbon dating of seashells, together with the reappraisal of shoreline ages from previous works, testify a long-term uplift rate of 2.5-2.7 mm/y. This average value, however, includes periods in which the vertical motions vary significantly: 2.6-3.2 mm/y subsidence rate from 42 ka to 23 ka, followed by ~7.7 mm/y sustained uplift rate from 23 ka to present. The last ~5 ky shows a relatively slower uplift rate of 3.0-3.3 mm/y, yet slightly higher than the long-term average. A preliminary tectonic model attempts at explaining these up and down motions by across-strike partitioning of fault activity in the subduction zone.
On the left, Kalamia site notches and their elevations (a) Panorama showing three raised shorelines; (b) A band of lithophagid boreholes marking shoreline S2; (c) S5 shoreline; notice the cave in the background and the sandy-gravel deposit on the foreground; (d) S6 shoreline; notice the cave on the left and the notch carved in the bedrock, filled with gravel.
On the right, graph showing vertical displacement vs. shoreline ages.Yellow dashed line represents the long-term average uplift trend; blue dashed line depicts main up-and-down trend. Notice that Kel14C and Sha14C ages are not calibrated. The star symbol marks a sample age discarded by Wegmann (2008) because of contamination.
“The Italian present-day stress map”
Paola Montone, Maria Teresa Mariucci, Simona Pierdominici
Geophys. J. Int. (2012), 189, 705-716
In this paper, we present a significant update of the Italian present-day stress data compilation not only to improve the knowledge on the tectonic setting of the region or to constrain future geodynamic models, but also to understand the mechanics of processes linked to faulting and earthquakes. In this paper, we have analysed, revised and collected new contemporary stress data from borehole breakouts and we have assembled earthquake and fault data. In total, 206 new quality-ranked entries complete the definition of the horizontal stress orientation and tectonic regime in some areas, and bring new information mainly in Sicily and along the Apenninic belt. Now the global Italian data set consists of 715 data points, including 499 of A–C quality, representing an increase of 37 per cent compared to the previous compilation. The alignment of horizontal stresses measured in some regions, closely matches the ∼N–S first order stress field orientation of ongoing relative crustal motions between Eurasia and African plates. The Apenninic belt shows a diffuse extensional stress regime indicating a ∼NE–SW direction of extension, that we interpret as related to a second-order stress field. The horizontal stress rotations observed in peculiar areas reflect a complex interaction between first-order stress field and local effects revealing the importance of the tectonic structure orientations. In particular, in Sicily the new data delineate a more complete tectonic picture evidencing adjacent areas characterized by distinct stress regime: northern offshore of Sicily and in the Hyblean plateau the alignment of horizontal stresses is consistent with the crustal motions, whereas different directions have been observed along the belt and foredeep.
Present day stress map of Italy with minimum horizontal stress orientations (Shmin). Data derive from this paper and from Montone et al. (1999, 2004) compilation. Only A–C-quality data are included. Stress map is produced with CASMI (Heidbach & Höhne 2008) which is based on GMT from Wessel & Smith (1998).
Tectonic evidence for the ongoing Africa-Eurasia convergence in central Mediterranean foreland areas: A journey among long-lived shear zones, large earthquakes, and elusive fault motions.Daniela Di Bucci, Pierfrancesco Burrato, Paola Vannoli, Gianluca Valensise
We investigate the role of the Africa-Eurasia convergence in the recent tectonic evolution of the central Mediterranean. To this end we focused on two sectors of the Adriatic-Hyblean foreland of the Apennine-Maghrebian chain as they allow tectonic evidence for relative plate motions to be analyzed aside from the masking effect of other more local tectonic phenomena (e.g., subduction, chain building, etc.). We present a thorough review of data and interpretations on two major shear zones cutting these foreland sectors: the E-W Molise-Gondola in central Adriatic and the N-S Vizzini-Scicli in southern Sicily. The selected foreland areas exhibit remarkable similarities, including an unexpectedly high level of seismicity and the presence of the investigated shear zones since the Mesozoic. We analyze the tectonic framework, active tectonics, and seismicity of each of the foreland areas, highlighting the evolution of the tectonic understanding. In both areas, we find that current strains at midcrustal levels seem to respond to the same far-field force oriented NNW-SSE to NW-SE, similar to the orientation of the Africa-Eurasia convergence. We conclude that this convergence plays a primary role in the seismotectonics of the central Mediterranean and is partly accommodated by the reactivation of large Mesozoic shear zones.
Present-day stress in the surroundings of 2009 L’Aquila seismic sequence (Italy)AUTORI: M.T. Mariucci, P. Montone, S. Pierdominici
Geophysical Journal International, in press
Seismotectonic setting of the area. (a) 170 TDMT T-axis orientations of the 2009 L’Aquila sequence (http://www.eas.slu.edu/Earthquake Center/MECH.IT/); CMT focal mechanisms of the three mainshocks (A, B, C; Pondrelli et al. 2010); σ3 orientation from the 1992, 1994 and 1996 seismic sequences (Boncio et al. 2004); the Shmin orientation inferred from breakout analysis in the two deep wells Campotosto (C1) and Varoni (V1) and the major active normal and thrust faults. In the inset: the rose plot shows the orientation of the 186 coseismic ruptures identified at surface (Emergeo Working Group 2010). (b) Azimuth frequency histogram of TDMT T-axis orientations; the red lines represent the T-axis orientations from CMT data (Pondrelli et al. 2010). (c) The chart shows the TDMT T-axis azimuth distribution versus depth together with the Shmin orientation of the boreholes (yellow stars) and the σ3 (red circle). (d) The chart shows TDMT T-axis versus their magnitude.
The axial zone of the Apenninic belt in central Italy is a tectonically active region affected by post-orogenic Quaternary extension. The present-day stress field is characterized by a minimum horizontal stress (Shmin) ∼NE–SW oriented, derived mainly from earthquake focal mechanisms and secondarily from borehole breakouts and fault data. The paper describes the computation of the Shmin orientation along two deep boreholes located in the vicinity of the area hit by the 2009 April 6, Mw 6.3 L’Aquila earthquake. The analysed wells show breakout zones at a depth range between 1.4 and 4.6 km, giving precious information on a depth interval usually not investigated by any other data. The results show an Shmin N81±22° and N74±10° oriented for Varoni 1 and Campotosto 1 wells, respectively. The comparison among the breakouts, the 2009 seismic sequence, the past seismicity and the Quaternary faults indicates a small rotation of Shmin orientation from ∼NE, in the southern, to ∼ENE in the northern sector of the study area, where the wells are located. These differences are linked both to the natural variations of data and to the orientation of the main tectonic structures varying from NW–SE in the Abruzzi region to ∼N–S moving toward the Umbro-Marchean Apennines. The identification of constant Shmin orientations with depth derived from all the examined active stress data, confirms the breakouts as reliable stress indicators also for aseismic areas.
Trace element behaviour during interaction between basalt and crustal rocks at 0.5-0.8 GPa:
an experimental approach
Silvio Mollo, Valeria Misiti, Piergiorgio Scarlato
/>We experimentally investigate the trace elements behavior during the interaction between a partially molten crustal rock (MK72, meta-anorthosite) and a mantle-related magma (PF1, calc-alkaline basalt) at the Moho depth. Results show that a hybrid melt is formed at the basalt-crust contact, where plagioclase crystallizes (Figure a). This contact layer is enriched in trace elements which are incompatible with plagioclase crystals (Figure b). Under these conditions, the trace element diffusion coefficients are one order of magnitude larger than those expected. Moreover, the HFSE diffusivity in the hybrid melt is surprisingly higher than the REE one. Such a feature is related to the plagioclase crystallization that changes the trace elements liquid-liquid partitioning (i.e. diffusivity) over a transient equilibrium that will persist as long as the crystal growth proceeds.
Evidence for surface rupture associated with the Mw 6.3 L'Aquila earthquake sequence of April 2009 (central Italy)EMERGEO Working Group
An earthquake of Mw = 6.3 struck L'Aquila town (central Italy) on 6 April 2009 rupturing an ca.18-km-long SW-dipping normal fault. The aftershock area extended for a length of more than 35 km and included major aftershocks on 7 and 9 April and thousands of minor events. Surface faulting occurred along the SW-dipping Paganica fault with a continuous extent of ca.2.5 km. Ruptures consist of open cracks and vertical dislocations or warps (0.1m maximum throw) with an orientation of N130°–140°. Small triggered slip and shaking effects also took place along nearby synthetic and antithetic normal faults. The observed limited extent and small surface displacement of the Paganica ruptures with respect to the height of the fault scarps and vertical throws of palaeo-earthquakes along faults in the area put the faulting associated with the L'Aquila earthquake in perspective with respect to the maximum expected magnitude and the regional seismic hazard.
Clues to the identification of a seismogenic source from environmental effects. The case of the 1905 Calabria (southern Italy) earthquake.A. Tertulliani and L. Cucci
The September 8, 1905 Calabria (southern Italy) earthquake belongs to a peculiar family of highly destructive (I0=XI) seismic events, occurred at the dawning of the instrumental seismology, for which the location, geometry and size of the causative source are still substantially unconstrained. During the century elapsed since the earthquake, previous Authors identified three different epicenters that are more than 50 km apart and proposed magnitudes ranging from M≤6.2 to M=7.9. Even larger uncertainties were found when the geometry of the earthquake source was estimated. In this study, we constrain the magnitude, location and kinematics of the 1905 earthquake through the analysis of the remarkable environmental effects produced by the event (117 reviewed observations at 73 different localities throughout Calabria). The data used in our analysis include ground effects (landslides, rock falls and lateral spreads) and hydrological changes (streamflow variations, liquefaction, rise of water temperature and turbidity). To better define the magnitude of the event we use a number of empirical relations between seismic source parameters and distribution of ground effects and hydrological changes. In order to provide constraints to the location of the event and to the geometry of the source, we reproduce the coseismic static strain associated with different possible 1905 causative faults and compare its pattern to the documented streamflow changes. From the analysis of the seismically-induced environmental changes we find that: 1) the 1905 earthquake had a minimum magnitude M=6.7; 2) the event occurred in an offshore area west of the epicenters proposed by the historical seismic Catalogs; 3) it most likely occurred along a 100°N oriented normal fault with a left-lateral component, consistently with the seismotectonic setting of the area.
L’AQUILA (CENTRAL ITALY) EARTHQUAKES: THE PREDECESSORS OF THE APRIL 6, 2009 EVENT
A. Tertulliani, L. Cucci, M.Vecchi and A.Rossi
On April 6th 2009 a Mw=6.3, Imax=9-10 earthquake struck the Abruzzi region of Central Italy (http://portale.ingv.it/highlights/view?set_language=en). We find similarities in some peculiar />characteristics of the 2009 sequence and of some historical events occurred in the area, in particular in 1461 and 1762. We observe strong analogies in the distribution of the intensities and in the areas of the strongest effects produced by these shocks, as well as in the temporal evolution.
The 2009 quake severely devastated the town of L’Aquila (~73,000 inhabitants) and tens of villages located along the Middle Aterno Valley (hereinafter MAV, see Figure 1). One month after the event, its social impact was not yet definitive but certainly burdensome: 308 casualties, 47% homes damaged in the epicentral area, 20% heavily damaged (with an even worse situation in downtown L’Aquila), and about 40,000 people left homeless.
Although the magnitude of the event was not among the largest to have occurred in the Apennines, the Abruzzi earthquake can be considered as one of the most disastrous of the last century. The effects of the shaking were recorded not only in the epicentral zone but also in distant areas (e.g. as far as Rome - ~90 km from the epicenter – where it produced light damage), and heavily affected the cultural and socio-economic fabric of a wide region characterized by high seismic risk.
Archivio articoli in Evidenza