The knowledge of the crustal stress field is essential in the evaluation of the seismic hazard of... more The knowledge of the crustal stress field is essential in the evaluation of the seismic hazard of an area.To this aim, it is necessary to derive reliable focal mechanisms mainly when small earthquakes have to be included in the computation. The first motion focal mechanism solution techniques are still widely used in modern softwares. The determination of P-wave polarities with manual procedures can lead to human errors and it is time-consuming. Automatic procedures can avoid these drawbacks. Polarity identification is not a classification task easily expressed in terms of mathematical procedures, in fact classical automatic procedures can lead to worse results than those obtained by human operators. For this reason, the use of machine learning approaches results necessary to accomplish this task.With low computational costs, real-time analysis capabilities, no need for complicated pre-processing procedures, and truly competitive results, properly designed convolutional networks can be the answer to various problems, including those related to seismology. In our work, we present the Convolutional First Motion (CFM) network, a Deep Convolutional Neural Network (DCNN) used to classify seismic traces based on first motion polarities of P-waves. We used waveforms contained in two datasets. We prepared the first dataset selecting approximatively 150˙000 waveforms contained in the Italian seismic catalogue INSTANCE, specifically designed for the application of machine learning techniques. To this end we devised an analysis procedure using Principal Component Analysis and Self-Organising Maps, through which a clustering process individuated groups of suitable traces. A second dataset, not specifically designed for machine learning techniques, is prepared manually picking approximatively 4˙000 waveforms of earthquakes occurred between 2010 and 2014 at Mt. Pollino area in Italy, avoiding possible overlapping of waveforms between the two datasets. The network, trained on ~130˙000 time windows centred on P-wave arrival times of waveforms in the INSTANCE catalogue, achieved accuracies of 95.7% and 98.9% on two test sets: the Mt. Pollino dataset and part of the INSTANCE catalogue. Further testing showed that if we give the network waveforms with uncertain arrival times, it acquires robustness to this type of noise, still showing high-level of performance.We infer that the CFM network would be suitable in succession to automatic techniques that derive P-wave arrival times, for example techniques in which deep learning is used, in order to cover the entire data processing phase with machine learning. Given the incredible ability of DCNNs to model and process large volumes of data and their remarkable performance, it is reasonable to assume that deep learning will soon become the norm even in the context of first-motion polarity determination. This work was partially supported by the PRIN-2017 MATISSE project (no. 20177EPPN2), funded by the Ministry of Education and Research.
In a geologically interesting land like Italy, and in particular Campania, educating and informin... more In a geologically interesting land like Italy, and in particular Campania, educating and informing about the concept of risk in general, and specifically seismic risk, is of fundamental importance.The possibilities of seismic risk mitigation, in fact, depend not only on the scientific community but also on how well prepared and informed society is about the risk itself. It is, therefore, crucial to train the local population to increase disaster risk preparedness and resilience within our region.The Science Capital framework, developed by Prof. Louise Archer er al. (https://doi.org/10.1002/tea.21227), refers to a person’s science-related resources, such as their science-related understanding, knowledge, attitudes, activities, and social contacts. It also offers a key to defining how everyone's store of scientific knowledge is enriched and influenced by their habits, family, and network of contacts. Understanding this context and its dynamics helps us to enhance the resources available for scientific culture, with a view to building a competent and inclusive educational community. With this in minds, we built a didactic protocol dedicated to seismic risk perception taking into consideration the Science Capital framework.“Waves…a tool to explore our home!” allows students to acquire both specific topics, such as the physical quantities involved in an earthquake, its generation and its dynamics, and general concepts, such as the perception of seismic risk and the impact of man in the prevention, in the possible induction and in the response to an earthquake.An evaluation phase was carried out to assess the learning experience and the effectiveness of the science communication technique.This work has been supported by CORE ("sCience and human factor for Resilient sociEty") project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 .
During and after catastrophes it is important to investigate the role played by key governmental ... more During and after catastrophes it is important to investigate the role played by key governmental institutions and scientific community in vehiculating correct information to the whole population on how to manage the consequences of disasters in order to minimize losses and avoid other possible cascading effects. Indeed, messages spread out by policy makers and scientific community get positive effects, only if they are trusted by citizens.The European project entitled “sCience and human factOr for Resilient society” (H2020 CORE) considers trust as a key factor for the individuals’ risk perception, their behavioural response and disaster preparedness. Within this scenario, a survey is promoted by means of an online questionnaire including scales and indicators related to risk perception and trust by controlling for geographical context, socio-demographic and economic backgrounds together with direct and indirect individual experiences. The aim of the survey is twofold: on one hand, it permits to consider the effects on citizens’ behaviors by analysing different hazards, such as earthquakes, tsunami, wildfire, industrial accident, terrorist attack, flash flood and COVID-19 pandemic; on the other one, it allows to underline best practices adopted by institutions during emergencies in different countries by also investigating the role of fake news.The final aim is to release guidelines devoted to the policy makers and scientific community experts in order to understand what they can do to be trusted by communities. Acknowledgment: The present abstract has been produced for the CORE project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101021746.
Storage of energy-related products in the geological subsurface provides reserve capacity, resili... more Storage of energy-related products in the geological subsurface provides reserve capacity, resilience, and security to the energy supply chain. Sequestration of energy-related products ensures long-term isolation from the environment and, for CO 2 , a reduction in atmospheric emissions. Both porous-rock media and engineered caverns can provide the large storage volumes needed for energy security and supply-chain resilience today and in the future. Methods for site characterization and modelling, monitoring, and inventory verification have been developed and deployed to identify and mitigate geological threats and hazards such as induced seismicity and loss of containment. Broader considerations such as life-cycle analysis, environment, social and governance (ESG) impact and effective engagement with stakeholders can reduce project uncertainty and cost while promoting sustainability during the ongoing energy transition toward net-zero or low-carbon economies.
This paper presents a high-level overview of site characterization, risk analysis and monitoring ... more This paper presents a high-level overview of site characterization, risk analysis and monitoring priorities for underground energy-related product storage or sequestration facilities. The siting of an underground storage or sequestration facility depends on several important factors beginning with the area of review. Collection of all existing and available records and data from within the rock volume, including potential vulnerabilities such as prior containment issues, proximity to infrastructure and/or population centres, must be evaluated. Baselining of natural processes before storage or sequestration operations begin provides the basis for assessing the effects of storage or sequestration on the surroundings. These initial investigations include geological, geophysical and geochemical analyses of the suitability of the geological host rock and environs for storage or sequestration. A risk analysis identifies and evaluates threats and hazards, the potential impact should they d...
<p>Risk perception is a concept of fundamental importance for the resilienc... more <p>Risk perception is a concept of fundamental importance for the resilience of societies. An important effort to raise the level of risk awareness must be made by the scientific community, which must adopt innovative communication techniques to get closer to the local community. A striking example of how crucial scientific communication is to risk perception was and still is Covid 19. Which allowed us to appreciate how important, if not necessary, it is to focus the energies of the scientific community not only on pure research, but also on how its outputs are communicated to the public.</p><p>It is therefore of fundamental importance for the scientific and civil community to disseminate information on the subject to create greater individual awareness and sensitivity, and to enable all citizens to make a tangible contribution to environmental protection through virtuous behaviour in everyday life, even outside the school/work context. The possibilities of risk mitigation, in fact, depend not only on the scientific community but also on how well prepared and informed society is about the risk itself. It is, therefore, crucial to train the local population to increase disaster risk preparedness and resilience of the society.</p><p>The younger generation plays a key role in the scientific awareness of society, representing both the future of society and a conduit to reach and educate their families.</p><p>In this perspective, the use of Serious Games, which is certainly an innovative practice in science communication, is gaining momentum since it favours participants' learning through their active involvement in the activities.</p><p>During the COVID-19 pandemic, we developed, using serious games, two didactic experiences, one dedicated to seismic risk (ALARM) and the other dedicated to climate change (Finding Gaia), targeting secondary school students, their families and science enthusiasts. Both experiences are characterised by an approach that is virtual and inclusive, allowing participation to people with motor disabilities, and fully interactive, through a series of quizzes, puzzles, and tasks of different difficulty, to include more and less experts/enthusiasts and exploit not only top-down but also peer-to-peer learning.</p><p>Moreover, these experiences encourage the use of certain topics by allowing the basic concepts to be used in everyday life while the guidance of experts throughout the game allow a critical understanding of the topic.</p><p>Before the start and at the end of any of these activities, an evaluation phase was carried out to assess the learning experience and the effectiveness of the science communication technique. For both practices, it was also found that, thanks to the introduction of the serious game, the virtual characteristic of the experience was evaluated as not negative, even though all the experiences were carried out during the COVID19 pandemic, with obvious repercussions on the disposition of the participants.</p><p>This work has been supported by CORE ("sCience and human factor for Resilient sociEty") project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</p>
Bulletin of the Seismological Society of America, Aug 1, 1995
Abstract Small earthquake records are increasingly being used as empirical Green's functions... more Abstract Small earthquake records are increasingly being used as empirical Green's functions to estimate the source time functions (STFs) of large earth-quakes. This is generally accomplished in the frequency domain by computing the ratio of the large to the small event spectrum ...
<p>The Mt. Pollino area has been affected by a 4-year long seismic sequence... more <p>The Mt. Pollino area has been affected by a 4-year long seismic sequence, occurred between 2010 and 2014 and characterized by low-to-moderate seismicity and two moderate events (M<sub>L </sub>4.3 and M<sub>L </sub>5.0). The sequence developed as a combination of swarm-like and aftershocks. The two main earthquakes occurred late in the sequence, with a slow-slip event starting 3-4 months before the largest earthquake and lasting for a year. Despite the lack of historical and instrumental recordings of strong earthquakes (M>6), paleo-seismological investigations confirm the occurrence in the last 10,000 years of at least two M 6.5-7 earthquakes on the Pollino and Castrovillari faults, located in the SE sector of the Mt. Pollino area. Thus, the area has been marked as the widest high seismic hazard gap in Italy.</p><p>In this study we present the most recent advancements in the comprehension of the main peculiarities of the last seismic sequence and of its space and time evolution.   </p><p>New local 3D P- and S-wave tomographic images offered a detailed picture of the main lithological units involved in the sequence and more reliable earthquake hypocenter locations. The inferred velocity contrasts have been compared with 2D scattering and absorption maps computed for the area, along with total direct wave attenuation. Clusters of events of similar waveforms (cross-correlation higher than 0.8) have been selected and located applying the master-slave relative location technique. New fault mechanisms have been computed. These mechanisms allowed modeling the local stress field and performing a Focal Mechanism Tomography. Its result was an evaluation of the excess of pore fluid pressure in the volume interested by the sequence. A 1D diffusivity analysis suggests a pore fluid pressure diffusion which, in addition to the Coulomb static stress transfer, can explain the delayed triggering of the two larger events.</p><p>This work has been supported by the CORE (“sCience and human factor for Resilient sociEty”) project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</p>
A newly developped method of 3-D Joint Inversion of seismic and gravimetric data has been applied... more A newly developped method of 3-D Joint Inversion of seismic and gravimetric data has been applied to investigate the subsurface structure of Mt. Vesuvius (Italy). Mt. Vesuvius is a strato volcano located within a graben (Campania Plain) formed in Plio-Pleistocene. Campania Plain is bordered by mostly Mesozoic carbonaceous rocks. Mt. Vesuvius is the southernmost and the youngest of a group
The Pollino area, one of the largest seismic gaps in Italy, has been struck between 2010 and 2014... more The Pollino area, one of the largest seismic gaps in Italy, has been struck between 2010 and 2014 by a long-lasting seismic sequence. More than 10,000 small-to-medium earthquakes followed a temporal evolution typical of a seismic swarm and, to a lesser extent, of aftershocks following the two strongest events: a ML 4.3 on 28 May 2012 and a ML 5.0 on 25 October 2012. A delay of almost 4 months separated the two main events, with the first event occurring two years after the beginning of the swarm. A slow slip event began about three months before the strongest earthquake. High VP and high VP/VS values have been found in the swarm area, where clusters of events of similar waveforms have been identified in recent works. The distribution of seismicity has been driven by pore fluid pressure diffusion with relatively low diffusivity value.The present work aims to provide the first 3D images of scattering and absorption of the Pollino area at different frequency bands, measured through peak delay mapping and coda-attenuation tomography, respectively. We collected 870 earthquakes from the 2010 - 2014 seismic sequence and surrounding area, characterized by ML > 1.7, already applied in a recent tomographic work. We used the manual P-wave pickings of the waveforms to compute the peak delay as the lag between the P-wave onset and the maximum of the envelope. Instead, the coda window has been fixed for the entire dataset at 30 seconds after the origin time of the earthquakes, lasting for 15 seconds. This late lapse time allows us to interpret Qc-1 as a marker of the absorption.The preliminary results show a high scattering anomaly characterizing the seismogenic volume of the sequence and the newly identified faults surrounding the focal area. A strong scattering contrast has been identified south of the ML 5.0 plane. This contrast is likely related to the presence of a segment of the Pollino Fault that acts as a barrier for the Southern propagation of the sequence. High attenuation anomalies in areas already marked by high VP and high VP/VS confirm the role that fluids played in this complex sequence. These results, together with the recent outcomes, could give more insights about the seismic hazard of this complex area.This work was supported by the PRIN-2017 MATISSE project (no. 20177EPPN2), funded by the Ministry of Education and Research.
The Calabria-Lucania border region represents the transitional area between the Southern Apennine... more The Calabria-Lucania border region represents the transitional area between the Southern Apennines and the Northern sector of the Calabrian arc. Roughly the whole Apennine chain is struck by more or less intense earthquakes. While the northern and central parts of the chain are characterized by foreland contraction and hinterland extension, the Southern Apennine is characterized by a strike-slip kinematics in the eastern sector and by an extensional regime in the western sector. Strike-slip earthquakes have been observed also in the axial part of the Campania-Molise Apennines, rightly beneath the active extensional sector.The Calabria-Lucania border region is considered a seismic gap in the Apennine chain; few paleo-earthquakes, with magnitude ranging from 5 to 7, have been recorded in the area. During 2010-2014 the region was affected by a low-moderate instrumental seismicity (known as Pollino seismic sequence): thousands of earthquakes occurred. Analysis of that seismicity revealed a shallow hypocentral distribution located into the first few km below the surface, and focal mechanisms of the strongest events of the sequence are consistent with upper crustal extensional deformation. While the shallow seismicity of Calabria-Lucania border region has been deeply studied after the 2010-2013 sequence, the sporadic deep seismicity needs a more detailed analysis.As highlighted by previous studies, instrumental seismicity recorded from 2013 to 2015 reveals the presence of a sporadic deep (from 9 to more than 20 km) seismicity. The events located between 9 and 17 km deep have transcurrent to transpressional kinematics with NE-SW trending P axes; while deeper events show a strike-slip kinematics with NW-SE trending P axes.We analyzed deep (> 10 km) seismicity recorded in the area from 2013 to nowadays. Starting from the picking of seismograms of more than 40 events (with M between 2.4 and 3.8), we analyzed the focal mechanisms of events computed using at least six good first motion observations. According to Ferranti et al., 2017, our results highlight the presence of a strike-slip/oblique kinematics at depths of more than 20 km. Between 10 and 20 km depth both dip-slip and strike-slip kinematics are present, with a predominance of the last ones, confirming the presence of a transition zone. Finally, we inverted the focal mechanisms dataset to infer about the stress field active in the region.
The knowledge of the crustal stress field is essential in the evaluation of the seismic hazard of... more The knowledge of the crustal stress field is essential in the evaluation of the seismic hazard of an area.To this aim, it is necessary to derive reliable focal mechanisms mainly when small earthquakes have to be included in the computation. The first motion focal mechanism solution techniques are still widely used in modern softwares. The determination of P-wave polarities with manual procedures can lead to human errors and it is time-consuming. Automatic procedures can avoid these drawbacks. Polarity identification is not a classification task easily expressed in terms of mathematical procedures, in fact classical automatic procedures can lead to worse results than those obtained by human operators. For this reason, the use of machine learning approaches results necessary to accomplish this task.With low computational costs, real-time analysis capabilities, no need for complicated pre-processing procedures, and truly competitive results, properly designed convolutional networks can be the answer to various problems, including those related to seismology. In our work, we present the Convolutional First Motion (CFM) network, a Deep Convolutional Neural Network (DCNN) used to classify seismic traces based on first motion polarities of P-waves. We used waveforms contained in two datasets. We prepared the first dataset selecting approximatively 150˙000 waveforms contained in the Italian seismic catalogue INSTANCE, specifically designed for the application of machine learning techniques. To this end we devised an analysis procedure using Principal Component Analysis and Self-Organising Maps, through which a clustering process individuated groups of suitable traces. A second dataset, not specifically designed for machine learning techniques, is prepared manually picking approximatively 4˙000 waveforms of earthquakes occurred between 2010 and 2014 at Mt. Pollino area in Italy, avoiding possible overlapping of waveforms between the two datasets. The network, trained on ~130˙000 time windows centred on P-wave arrival times of waveforms in the INSTANCE catalogue, achieved accuracies of 95.7% and 98.9% on two test sets: the Mt. Pollino dataset and part of the INSTANCE catalogue. Further testing showed that if we give the network waveforms with uncertain arrival times, it acquires robustness to this type of noise, still showing high-level of performance.We infer that the CFM network would be suitable in succession to automatic techniques that derive P-wave arrival times, for example techniques in which deep learning is used, in order to cover the entire data processing phase with machine learning. Given the incredible ability of DCNNs to model and process large volumes of data and their remarkable performance, it is reasonable to assume that deep learning will soon become the norm even in the context of first-motion polarity determination. This work was partially supported by the PRIN-2017 MATISSE project (no. 20177EPPN2), funded by the Ministry of Education and Research.
In a geologically interesting land like Italy, and in particular Campania, educating and informin... more In a geologically interesting land like Italy, and in particular Campania, educating and informing about the concept of risk in general, and specifically seismic risk, is of fundamental importance.The possibilities of seismic risk mitigation, in fact, depend not only on the scientific community but also on how well prepared and informed society is about the risk itself. It is, therefore, crucial to train the local population to increase disaster risk preparedness and resilience within our region.The Science Capital framework, developed by Prof. Louise Archer er al. (https://doi.org/10.1002/tea.21227), refers to a person’s science-related resources, such as their science-related understanding, knowledge, attitudes, activities, and social contacts. It also offers a key to defining how everyone's store of scientific knowledge is enriched and influenced by their habits, family, and network of contacts. Understanding this context and its dynamics helps us to enhance the resources available for scientific culture, with a view to building a competent and inclusive educational community. With this in minds, we built a didactic protocol dedicated to seismic risk perception taking into consideration the Science Capital framework.“Waves…a tool to explore our home!” allows students to acquire both specific topics, such as the physical quantities involved in an earthquake, its generation and its dynamics, and general concepts, such as the perception of seismic risk and the impact of man in the prevention, in the possible induction and in the response to an earthquake.An evaluation phase was carried out to assess the learning experience and the effectiveness of the science communication technique.This work has been supported by CORE ("sCience and human factor for Resilient sociEty") project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 .
During and after catastrophes it is important to investigate the role played by key governmental ... more During and after catastrophes it is important to investigate the role played by key governmental institutions and scientific community in vehiculating correct information to the whole population on how to manage the consequences of disasters in order to minimize losses and avoid other possible cascading effects. Indeed, messages spread out by policy makers and scientific community get positive effects, only if they are trusted by citizens.The European project entitled “sCience and human factOr for Resilient society” (H2020 CORE) considers trust as a key factor for the individuals’ risk perception, their behavioural response and disaster preparedness. Within this scenario, a survey is promoted by means of an online questionnaire including scales and indicators related to risk perception and trust by controlling for geographical context, socio-demographic and economic backgrounds together with direct and indirect individual experiences. The aim of the survey is twofold: on one hand, it permits to consider the effects on citizens’ behaviors by analysing different hazards, such as earthquakes, tsunami, wildfire, industrial accident, terrorist attack, flash flood and COVID-19 pandemic; on the other one, it allows to underline best practices adopted by institutions during emergencies in different countries by also investigating the role of fake news.The final aim is to release guidelines devoted to the policy makers and scientific community experts in order to understand what they can do to be trusted by communities. Acknowledgment: The present abstract has been produced for the CORE project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101021746.
Storage of energy-related products in the geological subsurface provides reserve capacity, resili... more Storage of energy-related products in the geological subsurface provides reserve capacity, resilience, and security to the energy supply chain. Sequestration of energy-related products ensures long-term isolation from the environment and, for CO 2 , a reduction in atmospheric emissions. Both porous-rock media and engineered caverns can provide the large storage volumes needed for energy security and supply-chain resilience today and in the future. Methods for site characterization and modelling, monitoring, and inventory verification have been developed and deployed to identify and mitigate geological threats and hazards such as induced seismicity and loss of containment. Broader considerations such as life-cycle analysis, environment, social and governance (ESG) impact and effective engagement with stakeholders can reduce project uncertainty and cost while promoting sustainability during the ongoing energy transition toward net-zero or low-carbon economies.
This paper presents a high-level overview of site characterization, risk analysis and monitoring ... more This paper presents a high-level overview of site characterization, risk analysis and monitoring priorities for underground energy-related product storage or sequestration facilities. The siting of an underground storage or sequestration facility depends on several important factors beginning with the area of review. Collection of all existing and available records and data from within the rock volume, including potential vulnerabilities such as prior containment issues, proximity to infrastructure and/or population centres, must be evaluated. Baselining of natural processes before storage or sequestration operations begin provides the basis for assessing the effects of storage or sequestration on the surroundings. These initial investigations include geological, geophysical and geochemical analyses of the suitability of the geological host rock and environs for storage or sequestration. A risk analysis identifies and evaluates threats and hazards, the potential impact should they d...
<p>Risk perception is a concept of fundamental importance for the resilienc... more <p>Risk perception is a concept of fundamental importance for the resilience of societies. An important effort to raise the level of risk awareness must be made by the scientific community, which must adopt innovative communication techniques to get closer to the local community. A striking example of how crucial scientific communication is to risk perception was and still is Covid 19. Which allowed us to appreciate how important, if not necessary, it is to focus the energies of the scientific community not only on pure research, but also on how its outputs are communicated to the public.</p><p>It is therefore of fundamental importance for the scientific and civil community to disseminate information on the subject to create greater individual awareness and sensitivity, and to enable all citizens to make a tangible contribution to environmental protection through virtuous behaviour in everyday life, even outside the school/work context. The possibilities of risk mitigation, in fact, depend not only on the scientific community but also on how well prepared and informed society is about the risk itself. It is, therefore, crucial to train the local population to increase disaster risk preparedness and resilience of the society.</p><p>The younger generation plays a key role in the scientific awareness of society, representing both the future of society and a conduit to reach and educate their families.</p><p>In this perspective, the use of Serious Games, which is certainly an innovative practice in science communication, is gaining momentum since it favours participants' learning through their active involvement in the activities.</p><p>During the COVID-19 pandemic, we developed, using serious games, two didactic experiences, one dedicated to seismic risk (ALARM) and the other dedicated to climate change (Finding Gaia), targeting secondary school students, their families and science enthusiasts. Both experiences are characterised by an approach that is virtual and inclusive, allowing participation to people with motor disabilities, and fully interactive, through a series of quizzes, puzzles, and tasks of different difficulty, to include more and less experts/enthusiasts and exploit not only top-down but also peer-to-peer learning.</p><p>Moreover, these experiences encourage the use of certain topics by allowing the basic concepts to be used in everyday life while the guidance of experts throughout the game allow a critical understanding of the topic.</p><p>Before the start and at the end of any of these activities, an evaluation phase was carried out to assess the learning experience and the effectiveness of the science communication technique. For both practices, it was also found that, thanks to the introduction of the serious game, the virtual characteristic of the experience was evaluated as not negative, even though all the experiences were carried out during the COVID19 pandemic, with obvious repercussions on the disposition of the participants.</p><p>This work has been supported by CORE ("sCience and human factor for Resilient sociEty") project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</p>
Bulletin of the Seismological Society of America, Aug 1, 1995
Abstract Small earthquake records are increasingly being used as empirical Green's functions... more Abstract Small earthquake records are increasingly being used as empirical Green's functions to estimate the source time functions (STFs) of large earth-quakes. This is generally accomplished in the frequency domain by computing the ratio of the large to the small event spectrum ...
<p>The Mt. Pollino area has been affected by a 4-year long seismic sequence... more <p>The Mt. Pollino area has been affected by a 4-year long seismic sequence, occurred between 2010 and 2014 and characterized by low-to-moderate seismicity and two moderate events (M<sub>L </sub>4.3 and M<sub>L </sub>5.0). The sequence developed as a combination of swarm-like and aftershocks. The two main earthquakes occurred late in the sequence, with a slow-slip event starting 3-4 months before the largest earthquake and lasting for a year. Despite the lack of historical and instrumental recordings of strong earthquakes (M>6), paleo-seismological investigations confirm the occurrence in the last 10,000 years of at least two M 6.5-7 earthquakes on the Pollino and Castrovillari faults, located in the SE sector of the Mt. Pollino area. Thus, the area has been marked as the widest high seismic hazard gap in Italy.</p><p>In this study we present the most recent advancements in the comprehension of the main peculiarities of the last seismic sequence and of its space and time evolution.   </p><p>New local 3D P- and S-wave tomographic images offered a detailed picture of the main lithological units involved in the sequence and more reliable earthquake hypocenter locations. The inferred velocity contrasts have been compared with 2D scattering and absorption maps computed for the area, along with total direct wave attenuation. Clusters of events of similar waveforms (cross-correlation higher than 0.8) have been selected and located applying the master-slave relative location technique. New fault mechanisms have been computed. These mechanisms allowed modeling the local stress field and performing a Focal Mechanism Tomography. Its result was an evaluation of the excess of pore fluid pressure in the volume interested by the sequence. A 1D diffusivity analysis suggests a pore fluid pressure diffusion which, in addition to the Coulomb static stress transfer, can explain the delayed triggering of the two larger events.</p><p>This work has been supported by the CORE (“sCience and human factor for Resilient sociEty”) project, funded from the European Union’s Horizon 2020 - research and innovation program under grant agreement No 101021746 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</p>
A newly developped method of 3-D Joint Inversion of seismic and gravimetric data has been applied... more A newly developped method of 3-D Joint Inversion of seismic and gravimetric data has been applied to investigate the subsurface structure of Mt. Vesuvius (Italy). Mt. Vesuvius is a strato volcano located within a graben (Campania Plain) formed in Plio-Pleistocene. Campania Plain is bordered by mostly Mesozoic carbonaceous rocks. Mt. Vesuvius is the southernmost and the youngest of a group
The Pollino area, one of the largest seismic gaps in Italy, has been struck between 2010 and 2014... more The Pollino area, one of the largest seismic gaps in Italy, has been struck between 2010 and 2014 by a long-lasting seismic sequence. More than 10,000 small-to-medium earthquakes followed a temporal evolution typical of a seismic swarm and, to a lesser extent, of aftershocks following the two strongest events: a ML 4.3 on 28 May 2012 and a ML 5.0 on 25 October 2012. A delay of almost 4 months separated the two main events, with the first event occurring two years after the beginning of the swarm. A slow slip event began about three months before the strongest earthquake. High VP and high VP/VS values have been found in the swarm area, where clusters of events of similar waveforms have been identified in recent works. The distribution of seismicity has been driven by pore fluid pressure diffusion with relatively low diffusivity value.The present work aims to provide the first 3D images of scattering and absorption of the Pollino area at different frequency bands, measured through peak delay mapping and coda-attenuation tomography, respectively. We collected 870 earthquakes from the 2010 - 2014 seismic sequence and surrounding area, characterized by ML > 1.7, already applied in a recent tomographic work. We used the manual P-wave pickings of the waveforms to compute the peak delay as the lag between the P-wave onset and the maximum of the envelope. Instead, the coda window has been fixed for the entire dataset at 30 seconds after the origin time of the earthquakes, lasting for 15 seconds. This late lapse time allows us to interpret Qc-1 as a marker of the absorption.The preliminary results show a high scattering anomaly characterizing the seismogenic volume of the sequence and the newly identified faults surrounding the focal area. A strong scattering contrast has been identified south of the ML 5.0 plane. This contrast is likely related to the presence of a segment of the Pollino Fault that acts as a barrier for the Southern propagation of the sequence. High attenuation anomalies in areas already marked by high VP and high VP/VS confirm the role that fluids played in this complex sequence. These results, together with the recent outcomes, could give more insights about the seismic hazard of this complex area.This work was supported by the PRIN-2017 MATISSE project (no. 20177EPPN2), funded by the Ministry of Education and Research.
The Calabria-Lucania border region represents the transitional area between the Southern Apennine... more The Calabria-Lucania border region represents the transitional area between the Southern Apennines and the Northern sector of the Calabrian arc. Roughly the whole Apennine chain is struck by more or less intense earthquakes. While the northern and central parts of the chain are characterized by foreland contraction and hinterland extension, the Southern Apennine is characterized by a strike-slip kinematics in the eastern sector and by an extensional regime in the western sector. Strike-slip earthquakes have been observed also in the axial part of the Campania-Molise Apennines, rightly beneath the active extensional sector.The Calabria-Lucania border region is considered a seismic gap in the Apennine chain; few paleo-earthquakes, with magnitude ranging from 5 to 7, have been recorded in the area. During 2010-2014 the region was affected by a low-moderate instrumental seismicity (known as Pollino seismic sequence): thousands of earthquakes occurred. Analysis of that seismicity revealed a shallow hypocentral distribution located into the first few km below the surface, and focal mechanisms of the strongest events of the sequence are consistent with upper crustal extensional deformation. While the shallow seismicity of Calabria-Lucania border region has been deeply studied after the 2010-2013 sequence, the sporadic deep seismicity needs a more detailed analysis.As highlighted by previous studies, instrumental seismicity recorded from 2013 to 2015 reveals the presence of a sporadic deep (from 9 to more than 20 km) seismicity. The events located between 9 and 17 km deep have transcurrent to transpressional kinematics with NE-SW trending P axes; while deeper events show a strike-slip kinematics with NW-SE trending P axes.We analyzed deep (> 10 km) seismicity recorded in the area from 2013 to nowadays. Starting from the picking of seismograms of more than 40 events (with M between 2.4 and 3.8), we analyzed the focal mechanisms of events computed using at least six good first motion observations. According to Ferranti et al., 2017, our results highlight the presence of a strike-slip/oblique kinematics at depths of more than 20 km. Between 10 and 20 km depth both dip-slip and strike-slip kinematics are present, with a predominance of the last ones, confirming the presence of a transition zone. Finally, we inverted the focal mechanisms dataset to infer about the stress field active in the region.
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Papers by Paolo CAPUANO