The recent tectonic stress field in the northeastern Baikal rift system (BRS) corresponds to the crustal deformation field. The stress-strain state of the Earth’s crust determines the fault network geometry and spatiotemporal structure of the epicentral field characterized by many earthquake swarms and earthquake migrations in the study area. In order to study the seismic process dynamics in different directions of the crustal deformation, the spatiotemporal analysis of earthquake time series has been made over the 1964–2015 instrumental period. To determine the relationship between crustal stress and spatiotemporal features of the epicentral field the seismic data were projected along horizontal stress tensor axes σ3 and σ2, consistent with major directions of the crustal deformation, a strike of major rifting structures, and a general azimuth of active fault groups. The NE-SW direction along the intermediate horizontal stress axes and main faulted arears exhibits slow earthquake migrations up to 60 km long, propagating with a modal velocity of about 30 kilometers per year. The NW-SE direction along the principal horizontal stress axes, orthogonal to the main faulted areas, is characterized by shorter migration sequences of less duration, propagating with a higher velocity than sequences registered in the NE-SW. The difference between the migration dynamics in mutually orthogonal directions can be attributed to the fault network configuration and the differences in the deformation process.
{"title":"The propagation velocity of seismic activity migrating along the directions of the geodynamic forces prevailing in the northeastern Baikal rift system, Russia","authors":"Olga F. Lukhneva, Anna Vladimirovna Novopashina","doi":"10.4401/ag-8654","DOIUrl":"https://doi.org/10.4401/ag-8654","url":null,"abstract":"The recent tectonic stress field in the northeastern Baikal rift system (BRS) corresponds to the crustal deformation field. The stress-strain state of the Earth’s crust determines the fault network geometry and spatiotemporal structure of the epicentral field characterized by many earthquake swarms and earthquake migrations in the study area. In order to study the seismic process dynamics in different directions of the crustal deformation, the spatiotemporal analysis of earthquake time series has been made over the 1964–2015 instrumental period. To determine the relationship between crustal stress and spatiotemporal features of the epicentral field the seismic data were projected along horizontal stress tensor axes σ3 and σ2, consistent with major directions of the crustal deformation, a strike of major rifting structures, and a general azimuth of active fault groups. The NE-SW direction along the intermediate horizontal stress axes and main faulted arears exhibits slow earthquake migrations up to 60 km long, propagating with a modal velocity of about 30 kilometers per year. The NW-SE direction along the principal horizontal stress axes, orthogonal to the main faulted areas, is characterized by shorter migration sequences of less duration, propagating with a higher velocity than sequences registered in the NE-SW. The difference between the migration dynamics in mutually orthogonal directions can be attributed to the fault network configuration and the differences in the deformation process.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"27 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85693437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High precision geoid determination is a challenging task at the national scale. Many efforts have been conducted to determine precise geoid, locally or globally. Geoid models have different precision depending on the type of information and the strategy employed when calculating the models. This contribution addresses the challenging problem of combining different regional and global geoid models, possibly combined with the geometric geoid derived from GNSS/leveling observations. The ultimate goal of this combination is to improve the precision of the combined model. We employ fitting an appropriate geometric surface to the geoid heights and estimating its (co)variance components. The proposed functional model uses the least squares 2D bi-cubic spline approximation (LS-BICSA) theory, which approximates the geoid model using a 2D spline surface fitted to an arbitrary set of data points in the region. The spline surface consists of third- order polynomial pieces that are smoothly connected together, imposing some continuity conditions at their boundaries. In addition, the least-squares variance component estimation (LS- VCE) is used to estimate precise weights and correlation among different models. We apply this strategy to the combined adjustment of the high-degree global gravitational model EIGEN-6C4, the regional geoid model IRG2016, and the Iranian geometric geoid derived from GNSS/leveling data. The accuracy of the constructed surface is investigated with five randomly selected subsamples of check points. The optimal combination of the two geoid models along with the GNSS/leveling data shows a reduction of 21 mm (~20%) in the RMSE values of discrepancies at the check points.
{"title":"Combination of regional and global geoid models at continental scale: application to Iranian geoid","authors":"Mahin Hosseini-Asl, Alireza Amiri-Simkooei, Abdolreza Safari","doi":"10.4401/ag-8643","DOIUrl":"https://doi.org/10.4401/ag-8643","url":null,"abstract":"High precision geoid determination is a challenging task at the national scale. Many efforts have been conducted to determine precise geoid, locally or globally. Geoid models have different precision depending on the type of information and the strategy employed when calculating the models. This contribution addresses the challenging problem of combining different regional and global geoid models, possibly combined with the geometric geoid derived from GNSS/leveling observations. The ultimate goal of this combination is to improve the precision of the combined model. We employ fitting an appropriate geometric surface to the geoid heights and estimating its (co)variance components. The proposed functional model uses the least squares 2D bi-cubic spline approximation (LS-BICSA) theory, which approximates the geoid model using a 2D spline surface fitted to an arbitrary set of data points in the region. The spline surface consists of third- order polynomial pieces that are smoothly connected together, imposing some continuity conditions at their boundaries. In addition, the least-squares variance component estimation (LS- VCE) is used to estimate precise weights and correlation among different models. We apply this strategy to the combined adjustment of the high-degree global gravitational model EIGEN-6C4, the regional geoid model IRG2016, and the Iranian geometric geoid derived from GNSS/leveling data. The accuracy of the constructed surface is investigated with five randomly selected subsamples of check points. The optimal combination of the two geoid models along with the GNSS/leveling data shows a reduction of 21 mm (~20%) in the RMSE values of discrepancies at the check points.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"19 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91196766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A retrospective analysis of the spatial and time variations of three main statistical parameters of the seismicity before recent 4 stronger earthquakes (2015 – 2020) in the southern Balkans is presented. The modern extended software package ZMAP with various advanced seismological functions for earthquake catalog analysis is used for estimating the spatial-time variations in a- value (seismic activity), b-value (slope of the recurrence graph) and z-value (parameter of the relative seismic quiescence). The catalog data from constantly updated catalog of the University of Athens for the period 1964-2020 and spatial window 32° - 44° N and 10° – 30° E are used for the various statistical interpretations. The main result of the whole analysis is that the abnormally low b-values and high z-values, defining the zones of relatively seismic quiescence, may be an indicator of imminent release of more significant stress in areas adjacent to the zones of relatively high a-values. Thus, the result of the proposed joint interpretation of the spatial-time variations of these three statistical parameters of seismicity could be considered as a kind of predictor of the stronger recent seismic events in the southern part of Balkans.
{"title":"Spatial and time variations of seismicity before strong earthquakes in the southern part of the Balkans","authors":"Emil Iliev Oynakov, Emil Aleksandrov Botev","doi":"10.4401/ag-8566","DOIUrl":"https://doi.org/10.4401/ag-8566","url":null,"abstract":"A retrospective analysis of the spatial and time variations of three main statistical parameters of the seismicity before recent 4 stronger earthquakes (2015 – 2020) in the southern Balkans is presented. The modern extended software package ZMAP with various advanced seismological functions for earthquake catalog analysis is used for estimating the spatial-time variations in a- value (seismic activity), b-value (slope of the recurrence graph) and z-value (parameter of the relative seismic quiescence). The catalog data from constantly updated catalog of the University of Athens for the period 1964-2020 and spatial window 32° - 44° N and 10° – 30° E are used for the various statistical interpretations. The main result of the whole analysis is that the abnormally low b-values and high z-values, defining the zones of relatively seismic quiescence, may be an indicator of imminent release of more significant stress in areas adjacent to the zones of relatively high a-values. Thus, the result of the proposed joint interpretation of the spatial-time variations of these three statistical parameters of seismicity could be considered as a kind of predictor of the stronger recent seismic events in the southern part of Balkans.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"17 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80985302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The goal of this paper is to develop a new empirical relationship between observed macroseismic intensity and strong ground motion parameters such as peak ground acceleration (PGA) and velocity (PGV) for the Vrancea subcrustal earthquakes. The recent subcrustal earthquakes provide valuable data to examine these relationships for Vrancea seismogenic region. This region is one of the most active seismic zones in Europe and it is well-known for the strong subcrustal earthquakes. We examine the correlation between the strong ground-motion records and the observed intensities for major and moderate earthquakes with Mw ≥ 5.4 and epicentral intensity in the range VI to IX MSK degrees that occurred in Vrancea zone in the period 1977-2009. The empirical relationships between maximum intensity and ground parameters obtained and published by various authors have shown that these parameters do not always show a one-to-one correspondence, and the errors associated with the intensity estimation from PGA/PGV are sometimes +/-2 MSK degree. In the present study, the relation between macroseismic intensity and PGA/PGV will be given both as a mathematical equation, but also as corresponding ground motion intervals. Because of the intensity data spreading and errors related to mathematical approximations, it is necessary to systematically monitor not only the acceleration and velocity but also all the other ground motion parameters. The mathematical relation between these parameters might be used for the rapid assessment of ground shaking severity and potential damages in the areas affected by the Vrancea earthquakes.
{"title":"Relationships between macroseismic intensity and peak ground acceleration and velocity for the Vrancea (Romania) subcrustal earthquakes","authors":"Iren-Adelina Moldovan, Angela Petruta Constantin, Raluca Partheniu, Bogdan Grecu, Constantin Ionescu","doi":"10.4401/ag-8448","DOIUrl":"https://doi.org/10.4401/ag-8448","url":null,"abstract":"The goal of this paper is to develop a new empirical relationship between observed macroseismic intensity and strong ground motion parameters such as peak ground acceleration (PGA) and velocity (PGV) for the Vrancea subcrustal earthquakes. The recent subcrustal earthquakes provide valuable data to examine these relationships for Vrancea seismogenic region. This region is one of the most active seismic zones in Europe and it is well-known for the strong subcrustal earthquakes. We examine the correlation between the strong ground-motion records and the observed intensities for major and moderate earthquakes with Mw ≥ 5.4 and epicentral intensity in the range VI to IX MSK degrees that occurred in Vrancea zone in the period 1977-2009. The empirical relationships between maximum intensity and ground parameters obtained and published by various authors have shown that these parameters do not always show a one-to-one correspondence, and the errors associated with the intensity estimation from PGA/PGV are sometimes +/-2 MSK degree. In the present study, the relation between macroseismic intensity and PGA/PGV will be given both as a mathematical equation, but also as corresponding ground motion intervals. Because of the intensity data spreading and errors related to mathematical approximations, it is necessary to systematically monitor not only the acceleration and velocity but also all the other ground motion parameters. The mathematical relation between these parameters might be used for the rapid assessment of ground shaking severity and potential damages in the areas affected by the Vrancea earthquakes.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"28 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86116295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
he focus of this study is the analysis of a cave in Central Italy, the Beatrice Cenci cave, in order to point out and constrain evidence of possible past earthquakes and of fault activity in the area. We performed a survey of seismic related damages within the cave. This included the analysis of broken/collapsed speleothems, the recognition of structural collapse, of tilting/growth alteration in the speleothems, and the mapping of fractures, joints and/or faults. To timely set the occurrence of the recognized damage, organic sediments were dated with 14C radiocarbon method. The results merged toward the recognition of two distinct seismic shaking events affecting the cave environment, one older than 30 kyr and another around 7 kyr. The deformation observed within the cave led us to the hypothesis that the events of damage were possibly linked to the activity of the regional tectonic lineament that crosses the cave, i.e., the Liri normal fault. The morphology and the evolution of the cave appear controlled by the fault zone. These speleoseismological results provided a new contribution on the knowledge of the past activity of the Liri fault and on the earthquake history of this sector of Central Apennines.
{"title":"Earthquake effects and insights on fault activity at the Beatrice Cenci cave (Abruzzo, Central Apennines)","authors":"Laura Leonilde Alfonsi, Francesca Romana Cinti","doi":"10.4401/ag-8571","DOIUrl":"https://doi.org/10.4401/ag-8571","url":null,"abstract":"he focus of this study is the analysis of a cave in Central Italy, the Beatrice Cenci cave, in order to point out and constrain evidence of possible past earthquakes and of fault activity in the area. We performed a survey of seismic related damages within the cave. This included the analysis of broken/collapsed speleothems, the recognition of structural collapse, of tilting/growth alteration in the speleothems, and the mapping of fractures, joints and/or faults. To timely set the occurrence of the recognized damage, organic sediments were dated with 14C radiocarbon method. The results merged toward the recognition of two distinct seismic shaking events affecting the cave environment, one older than 30 kyr and another around 7 kyr. The deformation observed within the cave led us to the hypothesis that the events of damage were possibly linked to the activity of the regional tectonic lineament that crosses the cave, i.e., the Liri normal fault. The morphology and the evolution of the cave appear controlled by the fault zone. These speleoseismological results provided a new contribution on the knowledge of the past activity of the Liri fault and on the earthquake history of this sector of Central Apennines.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"68 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80072575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aashiq Hussain Bhat, Bilal Ahmad Ganaie, T K Ramkumar, Manzoor A Malik, P Pavan Chaitanya
We report the observation of plasma depletions/plumes in the F region ionosphere over a low to middle latitude transition region in the Indian sector. The observation of these plasma depletions is based on the data obtained in May 2019 through the all-sky airglow CCD imager installed in the campus of University of Kashmir, Srinagar (34.12 °N, 74.83 °E, magnetic latitude 25.91 °N). The depletions on the two consecutive nights of 05 and 06 May 2019 are aligned along the North-South (N-S) direction and drift westward. Several depletion bands along with some enhancement bands are seen in the 630-nm airglow images throughout the two nights. The observed structures show certain characteristics similar to Medium Scale Traveling Ionospheric Disturbances (MSTIDs) but these airglow features are not completely periodic. Further, in the observed depletion bands some East-West asymmetries are observed along with the structured tree-like branches of the airglow depletions. Some depletion bands even bifurcate leading to the inference that the structures are signatures of plasma irregularities rather than the usual MSTIDs observed in low-mid latitude transition region. The westward drift of the depletions especially during geomagnetic quiet times over this region makes this study significant since it offers a possible evidence that shows extension of spread F irregularities from the mid latitude region to the low-mid latitude transition region. In this paper, we point out some possible mechanisms related to the occurrence of plasma depletions at this region and their westward movement during geomagnetic quiet times.
{"title":"Westward Drift of Ionospheric Plasma Irregularities over a Low to Mid-latitude Transition Region in Indian Sector","authors":"Aashiq Hussain Bhat, Bilal Ahmad Ganaie, T K Ramkumar, Manzoor A Malik, P Pavan Chaitanya","doi":"10.4401/ag-8510","DOIUrl":"https://doi.org/10.4401/ag-8510","url":null,"abstract":"We report the observation of plasma depletions/plumes in the F region ionosphere over a low to middle latitude transition region in the Indian sector. The observation of these plasma depletions is based on the data obtained in May 2019 through the all-sky airglow CCD imager installed in the campus of University of Kashmir, Srinagar (34.12 °N, 74.83 °E, magnetic latitude 25.91 °N). The depletions on the two consecutive nights of 05 and 06 May 2019 are aligned along the North-South (N-S) direction and drift westward. Several depletion bands along with some enhancement bands are seen in the 630-nm airglow images throughout the two nights. The observed structures show certain characteristics similar to Medium Scale Traveling Ionospheric Disturbances (MSTIDs) but these airglow features are not completely periodic. Further, in the observed depletion bands some East-West asymmetries are observed along with the structured tree-like branches of the airglow depletions. Some depletion bands even bifurcate leading to the inference that the structures are signatures of plasma irregularities rather than the usual MSTIDs observed in low-mid latitude transition region. The westward drift of the depletions especially during geomagnetic quiet times over this region makes this study significant since it offers a possible evidence that shows extension of spread F irregularities from the mid latitude region to the low-mid latitude transition region. In this paper, we point out some possible mechanisms related to the occurrence of plasma depletions at this region and their westward movement during geomagnetic quiet times. ","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"32 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77725891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrea Bizzarri, Alberto Petri, Andrea Baldassarri
The traction evolution is a fundamental ingredient to model the dynamics of an earthquake rupture which ultimately controls, during the coseismic phase, the energy release, the stress redistribution and the consequent excitation of seismic waves. In the present paper we explore the use of the friction behavior derived from laboratory shear experiments performed on granular materials at low normal stress. We find that the rheological properties emerging from these laboratory experiments can not be described in terms of preexisting governing models already presented in literature; our results indicate that neither rate–and state–dependent friction laws nor nonlinear slip–dependent models, commonly adopted for modeling earthquake ruptures, are able to capture all the features of the experimental data. Then, by exploiting a novel numerical approach, we directly incorporate the laboratory data into a code to simulate the fully dynamic propagation of a 3–D slip failure. We demonstrate that the rheology of the granular material, imposed as fault boundary condition, is dynamically consistent. Indeed, it is able to reproduce the basic features of a crustal earthquake, spontaneously accelerating up to some terminal rupture speed, both sub– and supershear.
{"title":"Earthquake dynamics constrained from laboratory experiments: new insights from granular materials","authors":"Andrea Bizzarri, Alberto Petri, Andrea Baldassarri","doi":"10.4401/ag-8613","DOIUrl":"https://doi.org/10.4401/ag-8613","url":null,"abstract":"The traction evolution is a fundamental ingredient to model the dynamics of an earthquake rupture which ultimately controls, during the coseismic phase, the energy release, the stress redistribution and the consequent excitation of seismic waves. In the present paper we explore the use of the friction behavior derived from laboratory shear experiments performed on granular materials at low normal stress. We find that the rheological properties emerging from these laboratory experiments can not be described in terms of preexisting governing models already presented in literature; our results indicate that neither rate–and state–dependent friction laws nor nonlinear slip–dependent models, commonly adopted for modeling earthquake ruptures, are able to capture all the features of the experimental data. Then, by exploiting a novel numerical approach, we directly incorporate the laboratory data into a code to simulate the fully dynamic propagation of a 3–D slip failure. We demonstrate that the rheology of the granular material, imposed as fault boundary condition, is dynamically consistent. Indeed, it is able to reproduce the basic features of a crustal earthquake, spontaneously accelerating up to some terminal rupture speed, both sub– and supershear.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"42 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79750053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gloria Maria Ristuccia, Pietro Bonfanti, Salvatore Giammanco
We describe the geochemical characteristics of groundwater samples collected in 23 water wells located on the northern margin of the Hyblean plateau (East Sicily). This area, mostly made of highly permeable carbonate rocks, is rich in low temperature (T < 50° C) hydrothermal groundwaters, distributed in an active sismogenetic zone, with several ENE-WSW-directed tectonic structures that drove magma to the surface during Upper Pliocene and Pleistocene. The chemical features suggest complex mixing between rainwater, CO2-rich groundwater, steam-heated groundwater and geothermal brines, as highlighted by Principal Component Analysis (PCA). Some parameters, however, indicate widespread pollution of the aquifers from human activities. Stable isotopes analysis confirms the meteoric origin of groundwater and supports the origin of dissolved CO2 mostly from mantle degassing through deep tectonic faults. Geothermometric estimates, mostly based on quartz and Saturation Indexes geothermometers, suggest minimum reservoir temperature between 100 and 120° C.
{"title":"A hydrogeochemical approach to the characterization of low-enthalpy geothermal systems: the Scordia – Lentini graben (Sicily, Italy)","authors":"Gloria Maria Ristuccia, Pietro Bonfanti, Salvatore Giammanco","doi":"10.4401/ag-8536","DOIUrl":"https://doi.org/10.4401/ag-8536","url":null,"abstract":"We describe the geochemical characteristics of groundwater samples collected in 23 water wells located on the northern margin of the Hyblean plateau (East Sicily). This area, mostly made of highly permeable carbonate rocks, is rich in low temperature (T < 50° C) hydrothermal groundwaters, distributed in an active sismogenetic zone, with several ENE-WSW-directed tectonic structures that drove magma to the surface during Upper Pliocene and Pleistocene. The chemical features suggest complex mixing between rainwater, CO2-rich groundwater, steam-heated groundwater and geothermal brines, as highlighted by Principal Component Analysis (PCA). Some parameters, however, indicate widespread pollution of the aquifers from human activities. Stable isotopes analysis confirms the meteoric origin of groundwater and supports the origin of dissolved CO2 mostly from mantle degassing through deep tectonic faults. Geothermometric estimates, mostly based on quartz and Saturation Indexes geothermometers, suggest minimum reservoir temperature between 100 and 120° C.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"95 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84395769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
• Today a CO2 storage/segregation is an important option for a significant enhancing of CO2 sinks, to reduce the net carbon emissions into our planet atmosphere. Such storage/sequestration is a complex process, dealing with many facets of decision about the site selection, taking into consideration the local geological, geothermal, hydrodynamic and hydrocarbon potentials. In such multifaceted context, a thermo-poro-elastic nonlinear analytic model of fluid pressure P in deep rocks, can play an important role. To tackle this dynamics we here examine a nonlinear model of fluid pressure transient also considering convection, thermal dynamics and fluid/rock "frictions”. In addition, we here show that pressure dynamics, induced by an eventual external time or areal forcing can allow simple analytical determinations of pressure transients in these deep porous media. Such processes indeed can have practical impacts on the CO2 evolution for storage in deep rocks and thus influence the final site choice for a deep CO2 injection. In synthesis, this model provides simple characterizations of thermo-poro-elastic transients for CO2 storage. 24 25 26
{"title":"An analytic nonlinear model of thermo-poro-elastic pressure transients in porous rocks 2 with application to deep CO2 storage.","authors":"Roman Kanivetsky, Ettore Salusti","doi":"10.4401/ag-8690","DOIUrl":"https://doi.org/10.4401/ag-8690","url":null,"abstract":"• Today a CO2 storage/segregation is an important option for a significant enhancing of CO2 sinks, to reduce the net carbon emissions into our planet atmosphere. Such storage/sequestration is a complex process, dealing with many facets of decision about the site selection, taking into consideration the local geological, geothermal, hydrodynamic and hydrocarbon potentials. In such multifaceted context, a thermo-poro-elastic nonlinear analytic model of fluid pressure P in deep rocks, can play an important role. To tackle this dynamics we here examine a nonlinear model of fluid pressure transient also considering convection, thermal dynamics and fluid/rock \"frictions”. In addition, we here show that pressure dynamics, induced by an eventual external time or areal forcing can allow simple analytical determinations of pressure transients in these deep porous media. Such processes indeed can have practical impacts on the CO2 evolution for storage in deep rocks and thus influence the final site choice for a deep CO2 injection. In synthesis, this model provides simple characterizations of thermo-poro-elastic transients for CO2 storage. 24 25 26","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"16 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86667998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The 8 September 1905 Calabria earthquake is the seismic event for which the Italian Seismic Catalogue shows the highest instrumental magnitude of the whole dataset. However, the reported Ms=7.47 was calculated over only two stations, and leaves room for a revision. In this work I provide a new estimate of the surface-wave magnitude of the earthquake calculated over sixteen individual values of magnitude from seven different stations. The new estimate is Ms=7.06±0.13, a value that is consistently lined up with other estimates provided by means of macroseismic or geological evidence. The novel estimate is stable despite alternative epicentral locations and different depths proposed for this event by several investigators. The net variation of almost half a unit magnitude implies a resizing of the seismogenic source of the event in the frame of the seismotectonics of the region, and highlights the strong need for a systematic revision of the instrumental magnitude estimates for several ‘historical’ earthquakes that occurred at the dawning of the instrumental seismology.
{"title":"THE RESIZING OF THE MOST POWERFUL ITALIAN INSTRUMENTAL EARTHQUAKE (SEPTEMBER 8, 1905, CALABRIA REGION, SOUTHERN ITALY)","authors":"Luigi Cucci","doi":"10.4401/ag-8675","DOIUrl":"https://doi.org/10.4401/ag-8675","url":null,"abstract":"The 8 September 1905 Calabria earthquake is the seismic event for which the Italian Seismic Catalogue shows the highest instrumental magnitude of the whole dataset. However, the reported Ms=7.47 was calculated over only two stations, and leaves room for a revision. In this work I provide a new estimate of the surface-wave magnitude of the earthquake calculated over sixteen individual values of magnitude from seven different stations. The new estimate is Ms=7.06±0.13, a value that is consistently lined up with other estimates provided by means of macroseismic or geological evidence. The novel estimate is stable despite alternative epicentral locations and different depths proposed for this event by several investigators. The net variation of almost half a unit magnitude implies a resizing of the seismogenic source of the event in the frame of the seismotectonics of the region, and highlights the strong need for a systematic revision of the instrumental magnitude estimates for several ‘historical’ earthquakes that occurred at the dawning of the instrumental seismology.","PeriodicalId":50766,"journal":{"name":"Annals of Geophysics","volume":"17 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76825906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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