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  • Open Access English
    Authors: 
    Jan Wiszniowski; Nguyen Van Giang; Beata Plesiewicz; Grzegorz Lizurek; Dinh Quoc Van; Le Quang Khoi; Stanislaw Lasocki;
    Project: EC | EPOS IP (676564)

    Song Tranh 2 hydropower plant and the reservoir containing backed up water are located in the Quang Nam province (Central Vietnam). The region experiences unusual seismic activity related to the reservoir impoundment, with earthquakes of magnitude up to 4.7. In result of cooperation between the Institute of Geophysics, Vietnam Academy of Sciences and Technology and the Institute of Geophysics, Polish Academy of Sciences a seismic network has been built to facilitate seismic monitoring of the Song Tranh 2 area. The network, operating since August 2013, consists of 10 seismic stations. Here we show that the network is sufficient for advanced data processing. The first results of monitoring of the earthquake activity in Song Tranh 2 area in the period between 2012 and 2014, especially the completeness of catalogs, study and comparisons between water level and the seismic activity suggest direct connection between reservoir exploitation and anthropogenic seismicity.

  • English
    Authors: 
    Fernando Monterroso (1; 2); Manuela Bonano (2; 3); Claudio de Luca (2); De Novellis Vincenzo (2); Riccardo Lanari (2); Michelle Manunta (2); Mariarosaria Manzo (2); Giovanni Onorato (2); +3 more
    Country: Italy
    Project: EC | EPOS IP (676564)

    During the last decades, the availability of Synthetic Aperture Radar (SAR) satellite missions, such as the ERS-1/2 and ENVISAT ones operating at C-band who have worked since 1992 to 2011, as well as the X-band COSMOSkyMed and TerraSAR-X constellations, up to the brand new Sentinel-1 mission, have strongly contributed to SAR data diffusion and popularity in the generation of different studies at different scales and in different research fields. One of the most popular SAR technique is the one referred to as Differential SAR Interferometry (DInSAR), which allows measuring with centimeter accuracy the Earth's surface deformation entity related to both natural and man-made hazards. Nowadays, with the increasing of SAR data availability provided by Sentinel-1 constellation of Copernicus European Program, which is composed by two twin satellites operating in C-band since 2014 and 2016, with a repeat pass of 6 days and with a global (i.e. worldwide) data acquisition policy, the SAR EO scenario is becoming more and more operational, thus mainly providing support for natural hazards monitoring. This allows, in theory, and disposing of sufficient computing power, the EO community to monitor, for instance, the deformation of every volcano or to obtain co-seismic displacement maps in a short time frame and anywhere in the world. Accordingly, in this work, we present a fully automatic and fast processing service for the generation of co-seismic displacement maps by using Sentinel-1 data. The implemented system is completely unsupervised and is triggered by the all significant (i.e. larger than a defined magnitude) seismic event registered by the online catalog as those provided by the United States Geological Survey (USGS) and the National Institute of Geophysics and Volcanology of Italy (INGV). The service has been specifically designed to operate for Civil Protection purposes. The generated DInSAR measurements are made available to the geoscience community through the EPOS Research Infrastructure and they will contribute to the creation of a global database of co-seismic displacement maps. Finally, it is worth noting that the developed system relies on widely common IT methods and protocols and is not specifically tied to a defined computing architecture, thus implying its portability, in view also of the European Commission Data and Information Access Services (DIAS) where satellite data (mainly Sentinel) and processing facilities are co-located to reduce the data transfer time during their processing.

  • Open Access English
    Authors: 
    Paul Martin; Laurent Remy; Maria Theodoridou; Keith G. Jeffery; Zhiming Zhao;
    Country: Netherlands
    Project: EC | ENVRI PLUS (654182), EC | ENVRI-FAIR (824068), EC | EPOS IP (676564), EC | VRE4EIC (676247)

    Virtual Research Environments (VREs), also known as science gateways or virtual laboratories, assist researchers in data science by integrating tools for data discovery, data retrieval, workflow management and researcher collaboration, often coupled with a specific computing infrastructure. Recently, the push for better open data science has led to the creation of a variety of dedicated research infrastructures (RIs) that gather data and provide services to different research communities, all of which can be used independently of any specific VRE. There is therefore a need for generic VREs that can be coupled with the resources of many different RIs simultaneously, easily customised to the needs of specific communities. The resource metadata produced by these RIs rarely all adhere to any one standard or vocabulary however, making it difficult to search and discover resources independently of their providers without some translation into a common framework. Cross-RI search can be expedited by using mapping services that harvest RI-published metadata to build unified resource catalogues, but the development and operation of such services pose a number of challenges. In this paper, we discuss some of these challenges and look specifically at the VRE4EIC Metadata Portal, which uses X3ML mappings to build a single catalogue for describing data products and other resources provided by multiple RIs. The Metadata Portal was built in accordance to the e-VRE Reference Architecture, a microservice-based architecture for generic modular VREs, and uses the CERIF standard to structure its catalogued metadata. We consider the extent to which it addresses the challenges of cross-RI search, particularly in the environmental and earth science domain, and how it can be further augmented, for example to take advantage of linked vocabularies to provide more intelligent semantic search across multiple domains of discourse.

  • Open Access English
    Authors: 
    Fengyu Xia; Jan Dousa;
    Project: EC | EPOS IP (676564)
  • Open Access English
    Authors: 
    Beata Orlecka-Sikora; Stanislaw Lasocki; J. Kocot; Tomasz Szepieniec; Jean Robert Grasso; Alexander Garcia-Aristizabal; Marc Schaming; Pawel Urban; G.M. Jones; I. G. Stimpson; +22 more
    Publisher: Springer Science and Business Media LLC
    Project: EC | SERA (730900), EC | EPOS IP (676564)

    Mining, water-reservoir impoundment, underground gas storage, geothermal energy exploitation and hydrocarbon extraction have the potential to cause rock deformation and earthquakes, which may be hazardous for people, infrastructure and the environment. Restricted access to data constitutes a barrier to assessing and mitigating the associated hazards. Thematic Core Service Anthropogenic Hazards (TCS AH) of the European Plate Observing System (EPOS) provides a novel e-research infrastructure. The core of this infrastructure, the IS-EPOS Platform (tcs.ah-epos.eu) connected to international data storage nodes offers open access to large grouped datasets (here termed episodes), comprising geoscientific and associated data from industrial activity along with a large set of embedded applications for their efficient data processing, analysis and visualization. The novel team-working features of the IS-EPOS Platform facilitate collaborative and interdisciplinary scientific research, public understanding of science, citizen science applications, knowledge dissemination, data-informed policy-making and the teaching of anthropogenic hazards related to georesource exploitation. TCS AH is one of 10 thematic core services forming EPOS, a solid earth science European Research Infrastructure Consortium (ERIC) (www.epos-ip.org).

  • Open Access English
    Authors: 
    Louis De Barros; Frédéric Cappa; Yves Guglielmi; Laure Duboeuf; Jean-Robert Grasso;
    Publisher: HAL CCSD
    Countries: United States, France
    Project: ANR | HYDROSEIS (ANR-13-JS06-0004), EC | SERA (730900), EC | EPOS IP (676564)

    AbstractThe ability to predict the magnitude of an earthquake caused by deep fluid injections is an important factor for assessing the safety of the reservoir storage and the seismic hazard. Here, we propose a new approach to evaluate the seismic energy released during fluid injection by integrating injection parameters, induced aseismic deformation, and the distance of earthquake sources from injection. We use data from ten injection experiments performed at a decameter scale into fault zones in limestone and shale formations. We observe that the seismic energy and the hydraulic energy similarly depend on the injected fluid volume (V), as they both scale as V3/2. They show, however, a large discrepancy, partly related to a large aseismic deformation. Therefore, to accurately predict the released seismic energy, aseismic deformation should be considered in the budget through the residual deformation measured at the injection. Alternatively, the minimal hypocentral distance from injection points and the critical fluid pressure for fault reactivation can be used for a better prediction of the seismic moment in the total compilation of earthquakes observed during these experiments. Complementary to the prediction based only on the injected fluid volume, our approach opens the possibility of using alternative monitoring parameters to improve traffic-light protocols for induced earthquakes and the regulation of operational injection activities.

  • English
    Authors: 
    F. Casu1; M. Bonano1; 2; R. Castaldo1; C. De Luca1; V. De Novellis1; R. Lanari1; M. Manunta1; M. Manzo1; G. Onorato1; +5 more
    Country: Italy
    Project: EC | EPOS IP (676564)

    We present an unsupervised and automatic system for volcano deformation monitoring via the Copernicus Sentinel-1 data. The system relies on the Parallel Small BAseline Subset (P-SBAS) approach, permitting us to generate updated displacement time series at every new Sentinel-1 acquisition over a selected area of interest in a fast and accurate way. The service is currently operative to monitor the main active Italian volcanoes in the framework of cooperation with the Italian Department of Civil Protection. The system is potentially extendable to every area on the Earth, thus making it suitable for surface displacement monitoring of a large variety of phenomena. Finally, the obtained results are made available to the scientific community through the EPOS Research Infrastructure.

  • Open Access English
    Authors: 
    Konstantinos Michail Leptokaropoulos; Monika Staszek; Stanislaw Lasocki; Patricia Martínez-Garzón; Grzegorz Kwiatek;
    Country: Germany
    Project: EC | EPOS IP (676564), EC | SHEER (640896)

    The Geysers geothermal field located in California, USA, is the largest geothermal site in the world, operating since the 1960s. We here investigate and quantify the correlation between temporal seismicity evolution and variation of the injection data by examination of time-series through specified statistical tools (binomial test to investigate significant rate changes, cross correlation between seismic and injection data, b-value variation analysis). To do so, we utilize seismicity and operational data associated with two injection wells (Prati-9 and Prati-29) which cover a time period of approximately 7 yr (from November 2007 to August 2014). The seismicity is found to be significantly positively correlated with the injection rate. The maximum correlation occurs with a seismic response delay of ∼2 weeks, following injection operations. Those results are very stable even after considering hypocentral uncertainties, by applying a vertical shift of the events foci up to 300 m. Our analysis indicates also time variations of b-value, which exhibits significant positive correlation with injection rates.

  • Open Access English
    Authors: 
    Walpersdorf, A.; Pinget, L.; Vernant, P.; Sue, C.; Deprez, A.;
    Publisher: HAL CCSD
    Country: France
    Project: ANR | RESIF-CORE (ANR-11-EQPX-0040), EC | EPOS IP (676564)

    International audience; The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range-perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present-day dynamics of the Western Alps.

  • Restricted English
    Authors: 
    Corti; G.[ 1 ]; Nencini; R.[ 2 ]; Skytta; P.[ 3 ];
    Publisher: Pergamon,, Oxford , Regno Unito
    Country: Italy
    Project: EC | EPOS IP (676564)

    Abstract We use new analogue modelling experiments to analyse the development of pull-apart basins in an upper crust characterised by the presence of pre-existing discrete fabrics. As in previous models, lateral movement of rigid basal plates induced strike-slip deformation of a sand-pack. Local extension allowing the formation of a pull-apart basin was produced by the step-over geometry of the master faults; in this area, a basal silicone layer was introduced to distribute deformation and reproduced a weaker crust in the basin. Conditions of neutral, overlapping and underlapping interacting master faults were reproduced. The model upper crust, modelled by a sand mixture, was characterised by the presence of pre-existing structures; the orientation of these inherited heterogeneities was systematically varied in different experiments. Model results indicate that, depending on their orientation with respect to the strike-slip displacement, pre-existing structures can be reactivated both within and at the margins of the pull-apart basins. Inside the basin, reactivation occurs when the pre-existing structures are orthogonal or sub-orthogonal to the strike-slip displacement; in this case, the pre-existing fabrics delay the development and linkage of cross-basin faults and increase the complexity of the deformation pattern giving rise to a new set of faults characterised by an atypical trend. Pre-existing fabrics oblique to the local extension direction may be partly reactivated in the central part of the basin as segments of cross-basin faults. At the margins of the pull-apart, reactivation occurs if the fabrics spatially coincide with the lateral boundaries of the silicone layer. In these conditions, reactivation allows a faster development of the border faults, which are less segmented than in the homogenous models; this also results in a more regular final geometry of the pull-apart.

Advanced search in
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
38 Research products, page 1 of 4
  • Open Access English
    Authors: 
    Jan Wiszniowski; Nguyen Van Giang; Beata Plesiewicz; Grzegorz Lizurek; Dinh Quoc Van; Le Quang Khoi; Stanislaw Lasocki;
    Project: EC | EPOS IP (676564)

    Song Tranh 2 hydropower plant and the reservoir containing backed up water are located in the Quang Nam province (Central Vietnam). The region experiences unusual seismic activity related to the reservoir impoundment, with earthquakes of magnitude up to 4.7. In result of cooperation between the Institute of Geophysics, Vietnam Academy of Sciences and Technology and the Institute of Geophysics, Polish Academy of Sciences a seismic network has been built to facilitate seismic monitoring of the Song Tranh 2 area. The network, operating since August 2013, consists of 10 seismic stations. Here we show that the network is sufficient for advanced data processing. The first results of monitoring of the earthquake activity in Song Tranh 2 area in the period between 2012 and 2014, especially the completeness of catalogs, study and comparisons between water level and the seismic activity suggest direct connection between reservoir exploitation and anthropogenic seismicity.

  • English
    Authors: 
    Fernando Monterroso (1; 2); Manuela Bonano (2; 3); Claudio de Luca (2); De Novellis Vincenzo (2); Riccardo Lanari (2); Michelle Manunta (2); Mariarosaria Manzo (2); Giovanni Onorato (2); +3 more
    Country: Italy
    Project: EC | EPOS IP (676564)

    During the last decades, the availability of Synthetic Aperture Radar (SAR) satellite missions, such as the ERS-1/2 and ENVISAT ones operating at C-band who have worked since 1992 to 2011, as well as the X-band COSMOSkyMed and TerraSAR-X constellations, up to the brand new Sentinel-1 mission, have strongly contributed to SAR data diffusion and popularity in the generation of different studies at different scales and in different research fields. One of the most popular SAR technique is the one referred to as Differential SAR Interferometry (DInSAR), which allows measuring with centimeter accuracy the Earth's surface deformation entity related to both natural and man-made hazards. Nowadays, with the increasing of SAR data availability provided by Sentinel-1 constellation of Copernicus European Program, which is composed by two twin satellites operating in C-band since 2014 and 2016, with a repeat pass of 6 days and with a global (i.e. worldwide) data acquisition policy, the SAR EO scenario is becoming more and more operational, thus mainly providing support for natural hazards monitoring. This allows, in theory, and disposing of sufficient computing power, the EO community to monitor, for instance, the deformation of every volcano or to obtain co-seismic displacement maps in a short time frame and anywhere in the world. Accordingly, in this work, we present a fully automatic and fast processing service for the generation of co-seismic displacement maps by using Sentinel-1 data. The implemented system is completely unsupervised and is triggered by the all significant (i.e. larger than a defined magnitude) seismic event registered by the online catalog as those provided by the United States Geological Survey (USGS) and the National Institute of Geophysics and Volcanology of Italy (INGV). The service has been specifically designed to operate for Civil Protection purposes. The generated DInSAR measurements are made available to the geoscience community through the EPOS Research Infrastructure and they will contribute to the creation of a global database of co-seismic displacement maps. Finally, it is worth noting that the developed system relies on widely common IT methods and protocols and is not specifically tied to a defined computing architecture, thus implying its portability, in view also of the European Commission Data and Information Access Services (DIAS) where satellite data (mainly Sentinel) and processing facilities are co-located to reduce the data transfer time during their processing.

  • Open Access English
    Authors: 
    Paul Martin; Laurent Remy; Maria Theodoridou; Keith G. Jeffery; Zhiming Zhao;
    Country: Netherlands
    Project: EC | ENVRI PLUS (654182), EC | ENVRI-FAIR (824068), EC | EPOS IP (676564), EC | VRE4EIC (676247)

    Virtual Research Environments (VREs), also known as science gateways or virtual laboratories, assist researchers in data science by integrating tools for data discovery, data retrieval, workflow management and researcher collaboration, often coupled with a specific computing infrastructure. Recently, the push for better open data science has led to the creation of a variety of dedicated research infrastructures (RIs) that gather data and provide services to different research communities, all of which can be used independently of any specific VRE. There is therefore a need for generic VREs that can be coupled with the resources of many different RIs simultaneously, easily customised to the needs of specific communities. The resource metadata produced by these RIs rarely all adhere to any one standard or vocabulary however, making it difficult to search and discover resources independently of their providers without some translation into a common framework. Cross-RI search can be expedited by using mapping services that harvest RI-published metadata to build unified resource catalogues, but the development and operation of such services pose a number of challenges. In this paper, we discuss some of these challenges and look specifically at the VRE4EIC Metadata Portal, which uses X3ML mappings to build a single catalogue for describing data products and other resources provided by multiple RIs. The Metadata Portal was built in accordance to the e-VRE Reference Architecture, a microservice-based architecture for generic modular VREs, and uses the CERIF standard to structure its catalogued metadata. We consider the extent to which it addresses the challenges of cross-RI search, particularly in the environmental and earth science domain, and how it can be further augmented, for example to take advantage of linked vocabularies to provide more intelligent semantic search across multiple domains of discourse.

  • Open Access English
    Authors: 
    Fengyu Xia; Jan Dousa;
    Project: EC | EPOS IP (676564)
  • Open Access English
    Authors: 
    Beata Orlecka-Sikora; Stanislaw Lasocki; J. Kocot; Tomasz Szepieniec; Jean Robert Grasso; Alexander Garcia-Aristizabal; Marc Schaming; Pawel Urban; G.M. Jones; I. G. Stimpson; +22 more
    Publisher: Springer Science and Business Media LLC
    Project: EC | SERA (730900), EC | EPOS IP (676564)

    Mining, water-reservoir impoundment, underground gas storage, geothermal energy exploitation and hydrocarbon extraction have the potential to cause rock deformation and earthquakes, which may be hazardous for people, infrastructure and the environment. Restricted access to data constitutes a barrier to assessing and mitigating the associated hazards. Thematic Core Service Anthropogenic Hazards (TCS AH) of the European Plate Observing System (EPOS) provides a novel e-research infrastructure. The core of this infrastructure, the IS-EPOS Platform (tcs.ah-epos.eu) connected to international data storage nodes offers open access to large grouped datasets (here termed episodes), comprising geoscientific and associated data from industrial activity along with a large set of embedded applications for their efficient data processing, analysis and visualization. The novel team-working features of the IS-EPOS Platform facilitate collaborative and interdisciplinary scientific research, public understanding of science, citizen science applications, knowledge dissemination, data-informed policy-making and the teaching of anthropogenic hazards related to georesource exploitation. TCS AH is one of 10 thematic core services forming EPOS, a solid earth science European Research Infrastructure Consortium (ERIC) (www.epos-ip.org).

  • Open Access English
    Authors: 
    Louis De Barros; Frédéric Cappa; Yves Guglielmi; Laure Duboeuf; Jean-Robert Grasso;
    Publisher: HAL CCSD
    Countries: United States, France
    Project: ANR | HYDROSEIS (ANR-13-JS06-0004), EC | SERA (730900), EC | EPOS IP (676564)

    AbstractThe ability to predict the magnitude of an earthquake caused by deep fluid injections is an important factor for assessing the safety of the reservoir storage and the seismic hazard. Here, we propose a new approach to evaluate the seismic energy released during fluid injection by integrating injection parameters, induced aseismic deformation, and the distance of earthquake sources from injection. We use data from ten injection experiments performed at a decameter scale into fault zones in limestone and shale formations. We observe that the seismic energy and the hydraulic energy similarly depend on the injected fluid volume (V), as they both scale as V3/2. They show, however, a large discrepancy, partly related to a large aseismic deformation. Therefore, to accurately predict the released seismic energy, aseismic deformation should be considered in the budget through the residual deformation measured at the injection. Alternatively, the minimal hypocentral distance from injection points and the critical fluid pressure for fault reactivation can be used for a better prediction of the seismic moment in the total compilation of earthquakes observed during these experiments. Complementary to the prediction based only on the injected fluid volume, our approach opens the possibility of using alternative monitoring parameters to improve traffic-light protocols for induced earthquakes and the regulation of operational injection activities.

  • English
    Authors: 
    F. Casu1; M. Bonano1; 2; R. Castaldo1; C. De Luca1; V. De Novellis1; R. Lanari1; M. Manunta1; M. Manzo1; G. Onorato1; +5 more
    Country: Italy
    Project: EC | EPOS IP (676564)

    We present an unsupervised and automatic system for volcano deformation monitoring via the Copernicus Sentinel-1 data. The system relies on the Parallel Small BAseline Subset (P-SBAS) approach, permitting us to generate updated displacement time series at every new Sentinel-1 acquisition over a selected area of interest in a fast and accurate way. The service is currently operative to monitor the main active Italian volcanoes in the framework of cooperation with the Italian Department of Civil Protection. The system is potentially extendable to every area on the Earth, thus making it suitable for surface displacement monitoring of a large variety of phenomena. Finally, the obtained results are made available to the scientific community through the EPOS Research Infrastructure.

  • Open Access English
    Authors: 
    Konstantinos Michail Leptokaropoulos; Monika Staszek; Stanislaw Lasocki; Patricia Martínez-Garzón; Grzegorz Kwiatek;
    Country: Germany
    Project: EC | EPOS IP (676564), EC | SHEER (640896)

    The Geysers geothermal field located in California, USA, is the largest geothermal site in the world, operating since the 1960s. We here investigate and quantify the correlation between temporal seismicity evolution and variation of the injection data by examination of time-series through specified statistical tools (binomial test to investigate significant rate changes, cross correlation between seismic and injection data, b-value variation analysis). To do so, we utilize seismicity and operational data associated with two injection wells (Prati-9 and Prati-29) which cover a time period of approximately 7 yr (from November 2007 to August 2014). The seismicity is found to be significantly positively correlated with the injection rate. The maximum correlation occurs with a seismic response delay of ∼2 weeks, following injection operations. Those results are very stable even after considering hypocentral uncertainties, by applying a vertical shift of the events foci up to 300 m. Our analysis indicates also time variations of b-value, which exhibits significant positive correlation with injection rates.

  • Open Access English
    Authors: 
    Walpersdorf, A.; Pinget, L.; Vernant, P.; Sue, C.; Deprez, A.;
    Publisher: HAL CCSD
    Country: France
    Project: ANR | RESIF-CORE (ANR-11-EQPX-0040), EC | EPOS IP (676564)

    International audience; The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range-perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present-day dynamics of the Western Alps.

  • Restricted English
    Authors: 
    Corti; G.[ 1 ]; Nencini; R.[ 2 ]; Skytta; P.[ 3 ];
    Publisher: Pergamon,, Oxford , Regno Unito
    Country: Italy
    Project: EC | EPOS IP (676564)

    Abstract We use new analogue modelling experiments to analyse the development of pull-apart basins in an upper crust characterised by the presence of pre-existing discrete fabrics. As in previous models, lateral movement of rigid basal plates induced strike-slip deformation of a sand-pack. Local extension allowing the formation of a pull-apart basin was produced by the step-over geometry of the master faults; in this area, a basal silicone layer was introduced to distribute deformation and reproduced a weaker crust in the basin. Conditions of neutral, overlapping and underlapping interacting master faults were reproduced. The model upper crust, modelled by a sand mixture, was characterised by the presence of pre-existing structures; the orientation of these inherited heterogeneities was systematically varied in different experiments. Model results indicate that, depending on their orientation with respect to the strike-slip displacement, pre-existing structures can be reactivated both within and at the margins of the pull-apart basins. Inside the basin, reactivation occurs when the pre-existing structures are orthogonal or sub-orthogonal to the strike-slip displacement; in this case, the pre-existing fabrics delay the development and linkage of cross-basin faults and increase the complexity of the deformation pattern giving rise to a new set of faults characterised by an atypical trend. Pre-existing fabrics oblique to the local extension direction may be partly reactivated in the central part of the basin as segments of cross-basin faults. At the margins of the pull-apart, reactivation occurs if the fabrics spatially coincide with the lateral boundaries of the silicone layer. In these conditions, reactivation allows a faster development of the border faults, which are less segmented than in the homogenous models; this also results in a more regular final geometry of the pull-apart.

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