Earthquake Mechanisms of the Mediterranean Area (EMMA) version 3: an improved tool for characterizing the tectonic deformation styles in the Mediterranean

Geophysical Research Abstracts, Vol. 11, EGU2009-7974, 2009 EGU General Assembly 2009 © Author(s) 2009 Earthquake Mechanisms of the Mediterranean Area (EMMA) version 3: an improved tool for characterizing the tectonic deformation styles in the Mediterranean. G. Vannucci (1), P. Imprescia (2), and P. Gasperini (3) (1) INGV-Istituto Nazionale di Geofisica e Vulcanologia, Via Donato Creti, 12, I-40128, Bologna (Italy), [email protected], (2) Dipartimento Scienze Geologiche, Università di Catania, Corso Italia, 57, I-95129 Catania (Italy), [email protected], (3) Dipartimento di Fisica, Università di Bologna, Viale Berti-Pichat 8, I-40127 Bologna (Italy), [email protected] EMMA (Earthquake Mechanisms of the Mediterranean Area) database contains available literature data with the goal of making them more usable and available. EMMA is continuously improving by the addition of further focal mechanisms found in literature. At the present time, EMMA pre-release 3 includes more than 12700 focal solutions, about twice of previous official release 2.2 (Vannucci and Gasperini, 2004). They cover a time window from 1905 to 2006. In the new release, many added solutions are in areas not much covered or completely uncovered in the previous one (e.g. Bulgaria, Germany, Anatolia). As in the previous versions (Vannucci and Gasperini, 2003 and 2004), we have uniformed the different formats and notations of the data available from different sources and we have tried to solve misprints, inaccuracies and inconsistencies that might make the data unusable for other investigations. By an automatic procedure based on several criteria, we have chosen the “most representative” (best) solution when more than one is available for the same earthquake. Thanks to this, we have obtained about 6000 best solutions. The end user can use the best solution obtained with our procedure or he can change criteria. The database allows to make selections and to export data files suitable to be handled by graphic software and user generated scripts. In the new version, still MS-ACCESS based, we have added geographic information to the display of the focal solution, as well as we have integrated the hypocentral and magnitude data found on the original papers with those reported by regional and local catalogs and bulletins. In order to make EMMA more accessible, a web version is currently in progress. Through an internet connection it will be possible data selection and export, without installation and configuration problems found in the past. EMMA was already used in the past and will be (hopefully) useful in the future to better characterize the tectonic deformation styles (e.g. by moment tensors sum within given areas or over regular geographical grids) particularly in areas of the European region where seismicity is moderate and only few CMT solutions are available. At the moment, we try to compute strain map for Mediterranean area, using EMMA data. In order to represent any recurrence in space, we identify small areas and apply to each one some spatial analyses. The work is still in progress, but preliminary results are satisfactory and in accord to previous studies

Current stress and strain-rate fields across the Dead Sea Fault System: Constraints from seismological data and GPS observations

The stress and strain-rate fields characterizing the Dead Sea Fault System are investigated by using seismological and geodetic observations. In order to assess spatial variations in the regional stress field, we compiled a multidisciplinary dataset of well-constrained horizontal indicators, by merging all available data reported in literature with the data obtained in this study through weighted stress inversions of focal plane solutions. Our findings indicate that the state of stress is characterized by the coexistence of a normal faulting stress regime with the primarily strike-slip one, according to the regional frame illustrated by previous geological and seismological observations. An updated velocity field computed from new observations and earlier published data depicts the general left-lateral motion of the Dead Sea Fault System well. In agreement with previous studies, we detected some differences in the slip-rate pattern between the northern and the southern sectors of the fault system. The geodetic strain-rate field highlights how much of the deformation is accommodated along the fault system itself in a narrow region. The comparison between the stress and the strain-rate directions reveals that both orientations are near-parallel, clearly indicating that present-day crustal stress and ground deformation patterns are chiefly driven by the same tectonic processes. (C) 2013 Elsevier B.V. All rights reserved

Earthquake Mechanisms of the Mediterranean Area (EMMA) version 3: an improved tool for characterizing the tectonic deformation styles in the Mediterranean

Geophysical Research Abstracts, Vol. 11, EGU2009-7974, 2009 EGU General Assembly 2009 © Author(s) 2009 Earthquake Mechanisms of the Mediterranean Area (EMMA) version 3: an improved tool for characterizing the tectonic deformation styles in the Mediterranean. G. Vannucci (1), P. Imprescia (2), and P. Gasperini (3) (1) INGV-Istituto Nazionale di Geofisica e Vulcanologia, Via Donato Creti, 12, I-40128, Bologna (Italy), [email protected], (2) Dipartimento Scienze Geologiche, Università di Catania, Corso Italia, 57, I-95129 Catania (Italy), [email protected], (3) Dipartimento di Fisica, Università di Bologna, Viale Berti-Pichat 8, I-40127 Bologna (Italy), [email protected] EMMA (Earthquake Mechanisms of the Mediterranean Area) database contains available literature data with the goal of making them more usable and available. EMMA is continuously improving by the addition of further focal mechanisms found in literature. At the present time, EMMA pre-release 3 includes more than 12700 focal solutions, about twice of previous official release 2.2 (Vannucci and Gasperini, 2004). They cover a time window from 1905 to 2006. In the new release, many added solutions are in areas not much covered or completely uncovered in the previous one (e.g. Bulgaria, Germany, Anatolia). As in the previous versions (Vannucci and Gasperini, 2003 and 2004), we have uniformed the different formats and notations of the data available from different sources and we have tried to solve misprints, inaccuracies and inconsistencies that might make the data unusable for other investigations. By an automatic procedure based on several criteria, we have chosen the “most representative” (best) solution when more than one is available for the same earthquake. Thanks to this, we have obtained about 6000 best solutions. The end user can use the best solution obtained with our procedure or he can change criteria. The database allows to make selections and to export data files suitable to be handled by graphic software and user generated scripts. In the new version, still MS-ACCESS based, we have added geographic information to the display of the focal solution, as well as we have integrated the hypocentral and magnitude data found on the original papers with those reported by regional and local catalogs and bulletins. In order to make EMMA more accessible, a web version is currently in progress. Through an internet connection it will be possible data selection and export, without installation and configuration problems found in the past. EMMA was already used in the past and will be (hopefully) useful in the future to better characterize the tectonic deformation styles (e.g. by moment tensors sum within given areas or over regular geographical grids) particularly in areas of the European region where seismicity is moderate and only few CMT solutions are available. At the moment, we try to compute strain map for Mediterranean area, using EMMA data. In order to represent any recurrence in space, we identify small areas and apply to each one some spatial analyses. The work is still in progress, but preliminary results are satisfactory and in accord to previous studies.PublishedWien5.2. TTC - Banche dati di sismologia strumentaleope

Current stress and strain-rate fields across the Dead Sea Fault system: constraints from seismological data and GPS observations.

The stress and strain-rate fields characterizing the Dead Sea Fault System are investigated by using seismological and geodetic observations. In order to assess spatial variations in the regional stress field, we compiled a multidisciplinary dataset of well-constrained horizontal indicators, by merging all available data reported in literature with the data obtained in this study through weighted stress inversions of focal plane solutions. Our findings indicate that the state of stress is characterized by the coexistence of a normal faulting stress regime with the primarily strike-slip one, according to the regional frame illustrated by previous geological and seismological observations. An updated velocity field computed from new observations and earlier published data, depicts the general left-lateral motion of the Dead Sea fault system well. In agreement with previous studies, we detected some differences in the slip-rate pattern between the northern and the southern sectors of the fault system. The geodetic strain-rate field highlights how much of the deformation is accommodated along the fault system itself in a narrow region. The comparison between the stress and the strain-rate directions reveals that both orientations are near-parallel, clearly indicating that present-day crustal stress and ground deformation patterns are chiefly driven by the same tectonic processes.Published305-3162T. Tettonica attivaJCR Journalrestricte

Current stress and strain-rate fields across the Dead Sea Fault system: constraints from seismological data and GPS observations.

The stress and strain-rate fields characterizing the Dead Sea Fault System are investigated by using seismological and geodetic observations. In order to assess spatial variations in the regional stress field, we compiled a multidisciplinary dataset of well-constrained horizontal indicators, by merging all available data reported in literature with the data obtained in this study through weighted stress inversions of focal plane solutions. Our findings indicate that the state of stress is characterized by the coexistence of a normal faulting stress regime with the primarily strike-slip one, according to the regional frame illustrated by previous geological and seismological observations. An updated velocity field computed from new observations and earlier published data, depicts the general left-lateral motion of the Dead Sea fault system well. In agreement with previous studies, we detected some differences in the slip-rate pattern between the northern and the southern sectors of the fault system. The geodetic strain-rate field highlights how much of the deformation is accommodated along the fault system itself in a narrow region. The comparison between the stress and the strain-rate directions reveals that both orientations are near-parallel, clearly indicating that present-day crustal stress and ground deformation patterns are chiefly driven by the same tectonic processes

An improved evaluation of the seismic/geodetic deformation-rate ratio for the Zagros Fold-and-Thrust collisional belt

We present an improved picture of the ongoing crustal deformation field for the Zagros Fold-and-Thrust Belt continental collision zone by using an extensive combination of both novel and published GPS observations. The main results define the significant amount of oblique Arabia-Eurasia convergence currently being absorbed within the Zagros: right-lateral shear along theNWtrending Main Recent fault inNWZagros and accommodated between fold-andthrust structures and NS right-lateral strike-slip faults on Southern Zagros. In addition, taking into account the 1909-2016 instrumental seismic catalogue, we provide a statistical evaluation of the seismic/geodetic deformation-rate ratio for the area. On Northern Zagros and on the Turkish-Iranian Plateau, a moderate to large fraction (~49 and >60 per cent, respectively) of the crustal deformation occurs seismically. On the Sanandaj-Sirjan zone, the seismic/geodetic deformation-rate ratio suggests that a small to moderate fraction (<40 per cent) of crustal deformation occurs seismically; locally, the occurrence of large historic earthquakes (M ≥ 6) coupled with the high geodetic deformation, could indicate overdue M ≥ 6 earthquakes. On Southern Zagros, aseismic strain dominates crustal deformation (the ratio ranges in the 15-33 per cent interval). Such aseismic deformation is probably related to the presence of the weak evaporitic Hormuz Formation which allows the occurrence of large aseismic motion on both subhorizontal faults and surfaces of décollement. These results, framed into the seismotectonic framework of the investigated region, confirm that the fold-and-thrust-dominated deformation is driven by buoyancy forces; by contrast, the shear-dominated deformation is primary driven by plate stresse

Regional centroid moment tensor solutions in Cyprus from 1977 to the present and seismotectonic implications

We analyzed digital seismic records in order to extend back in time the catalog of regional centroid moment tensors (RCMTs) for the Cyprus region. We applied the analysis and inversion methodology also used for the present-day seismicity on seismograms recorded at regional distance. We computed 18 new regional CMTs of earthquakes of moderate magnitude (4.8≤M≤5.5) which occurred in the Cyprus region for the time span 1977–1996. These new focal mechanisms improved the knowledge given by the previously computed solutions carried out by other institutions, as well as the dataset of available earthquake source parameters. The complete focal mechanism database contributed to better define the deformation styles in the study area and to obtain a detailed characterization of the geodynamics of the Cyprus area. New RCMTs support the hypothesis that Cyprus is located in the middle of the transition area from subduction to continental collision along the Africa–Arabian–Eurasian boundary. In particular, data confirm (a) this transition zone is strictly located west of Cyprus, probably related to a tear in the subduction system, and (b) the still active compression in the Cyprus Arc can be seen as a starting point of the continental collision eastward

Regional Moment Tensor Review: An Example from the 2 European–Mediterranean Region

The seismic moment tensor is the complete mathematical representation of the movement on a fault 10 during an earthquake, comprising of the couples of forces that produced it, the description of the fault 11 geometry, and its size by means of the scalar seismic moment M0. 12 The computation of seismic moment tensor has become a widely diffused activity because of the 13 relevance of this kind of data in seismotectonic and geodynamic studies and, in more recent times, 14 because it allows obtaining rapid information about a seismic event immediately after its occurrence. This 15 progress has been possible with the advent of modern standardized instruments since the early 1960s, 16 above all of the very broadband seismographic stations that started to record in the late 1970s. Further- 17 more, time after time, the easier availability of digital data impressed a strong incentive to improve the 18 procedures of source parameter computation.Unpublished1-154IT. Banche datirestricte