bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in seismic monitoring at Deception Island volcano (Antarctica) since the International Polar Year
Authors: Enrique Carmona  , Javier Almendros  , Rosa Martín  , Guillermo Cortés  , Gerardo Alguacil  , Javier Moreno  , José Benito Martín  , Antonio Martos  , Inmaculada Serrano  , Daniel Stich  , Jesús M. Ibáñez
Published: June 2021

Deception Island is an active volcano located in the south Shetland Islands, Antarctica. It constitutes a natural laboratory to test geophysical instruments in extreme conditions, since they have to endure not only the Antarctic climate but also the volcanic environment. Deception is one of the most visited places in Antarctica, both by scientists and tourists, which emphasize the importance of volcano monitoring. Seismic monitoring has been going on since 1986 during austral summer surveys. The recorded data include volcano-tectonic earthquakes, long-period events and volcanic tremor, among others. The level of seismicity ranges from quiet periods to seismic crises (e.g. 1992-1993, 1999). Our group has been involved in volcano monitoring at Deception Island since 1994. Based on this experience, in recent years we have made the most of the opportunities of the International Polar Year 2007-2008 to introduce advances in seismic monitoring along four lines: (1) the improvement of the seismic network installed for seismic monitoring during the summer surveys; (2) the development and improvement of seismic arrays for the detection and characterization of seismo-volcanic signals; (3) the design of automated event recognition tools, to simplify the process of data interpretation; and (4) the deployment of permanent seismic stations. These advances help us to obtain more data of better quality, and therefore to improve our interpretation of the seismo-volcanic activity at Deception Island, which is a crucial step in terms of hazards assessment.
Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors
Authors: Masaki Kanao  , Douglas A. Wiens  , Satoru Tanaka  , Andrew A. Nyblade  , Genti Toyokuni  , Patrick J. Shore  , Seiji Tsuboi  , David S. Heeszel  , Yusuke Usui  , Timothy Parker
Published: June 2021

“Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY) 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147), the GAmburtsev Mountain SEISmic experiment (GAMSEIS), a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185) were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A), Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN) in southern high latitude.
Observations of surface radiation and stratospheric processes at Thule Air Base, Greenland, during the IPY
Authors: Giovanni Muscari  , Claudia Di Biagio  , Alcide di Sarra  , Marco Cacciani  , Svend Erik Ascanius  , Pietro Paolo Bertagnolio  , Claudio Cesaroni  , Robert L. de Zafra  , Paul Eriksen  , Giorgio Fiocco  , Irene Fiorucci  , Daniele Fuà
Published: June 2021

Ground-based measurements of atmospheric parameters have been carried out for more than 20 years at the Network for the Detection of Atmospheric Composition Change (NDACC) station at Thule Air Base (76.5°N, 68.8°W), on the north-western coast of Greenland. Various instruments dedicated to the study of the lower and middle polar atmosphere are installed at Thule in the framework of a long standing collaboration among Danish, Italian, and US research institutes and universities. This effort aims at monitoring the composition, structure and dynamics of the polar stratosphere, and at studying the Arctic energy budget and the role played by different factors, such as aerosols, water vapour, and surface albedo. During the International Polar Year (IPY), in winter 2008-2009, an intensive measurement campaign was conducted at Thule within the framework of the IPY project “Ozone layer and UV radiation in a changing climate evaluated during IPY” (ORACLE-O3) which sought to improve our understanding of the complex mechanisms that lead to the Arctic stratospheric O3 depletion. The campaign involved a lidar system, measuring aerosol backscatter and depolarization ratios up to 35 km and atmospheric temperature profiles from 25 to 70 km altitude, a ground-based millimeter-wave spectrometer (GBMS) used to derive stratospheric mixing ratio profiles of different chemical species involved in the stratospheric ozone depletion cycle, and then ground-based radiometers and a Cimel sunphotometer to study the Arctic radiative budget at the surface. The observations show that the surface radiation budget is mainly regulated by the longwave component throughout most of the year. Clouds have a significant impact contributing to enhance the role of longwave radiation. Besides clouds, water vapour seasonal changes produce the largest modification in the shortwave component at the surface, followed by changes in surface albedo and in aerosol amounts. For what concerns the middle atmosphere, during the first part of winter 2008-2009 the cold polar vortex allowed for the formation of polar stratospheric clouds (PSCs) which were observed above Thule by means of the lidar. This period was also characterized by GBMS measurements of low values of O3 due to the catalytic reactions prompted by the PSCs. In mid-January, as the most intense Sudden Stratospheric Warming event ever observed in the Arctic occurred, GBMS and lidar measurements of O3, N2O, CO and temperature described its evolution as it propagated from the upper atmosphere to the lower stratosphere.
Geotechnical characterization and seismic response of shallow geological formations in downtown Lisbon
Authors: Paula Teves-Costa  , Isabel M. Almeida  , Isabel Rodrigues  , Rita Matildes  , Claudia Pinto
Published: June 2021

 

The geological and geotechnical characterization of shallow formations is one of the main steps in performing a microzonation study. This paper presents an example of the usefulness of the information compiled in a geological and geotechnical database for the estimation of the seismic response of the shallower formations of the Lisbon downtown area of Baixa. The geotechnical characterization of this area was performed based on the analysis of Standard Penetration Test (SPT) data compiled in the geological and geotechnical database. This database, connected to a geoscientific information system (CGIS), allows, also, the definition of 2D geological profiles used for estimating the thickness of the shallower layers. The shear-wave velocities (VS ) for each layer were estimated from empirical correlations using mean SPT values computed from the statistical evaluation of the compiled data. These VS values were further calibrated with ambient vibration recording analysis. The seismic response of Baixa’s superficial deposits was estimated by applying a 1D equivalent linear method to a set of soil profiles, regularly distributed across the area, and using synthetic accelerograms to simulate input motions associated with probable earthquake occurrences in Lisbon. The results are presented in terms of maps of predominant frequencies, with the corresponding amplification level, as well as spectral amplification factors for 1 Hz and 2.5 Hz. The results show that the fundamental frequency of the Baixa area is between 1.2 Hz and 2 Hz, for the whole central valley, reaching 3 Hz near the edges where anthroprogenic and alluvial deposits have less expression. Amplification factors up to 5 were obtained. These results were achieved regardless of the considered input motion. The similarity of the obtained fundamental frequency with the natural frequency of Baixa’s old building stock increases the probability of resonance effects in future earthquakes.
Strain patterns along the Kaparelli–Asopos rift (central Greece) from campaign GPS data
Authors: Aggeliki Marinou  , Athanassios Ganas  , Kalliopi Papazissi  , Demitris Paradissis
Published: June 2021

We present results from four GPS campaigns in the broader Kaparelli–Asopos area in central Greece. This area is undergoing extension as demonstrated by seismological, geodetic and geological data. The east-west striking Kaparelli normal fault ruptured during the March 4, 1981, M = 6.3 earthquake and created km-long surface breaks with the downthrown side to the south. The geodetic results include: determination of station coordinates in the ITRF 2005 frame, computation of station velocities with respect to stable Europe and strain rate tensor estimates. The pattern of velocities along the east-west direction (parallel to the rift axis; 40 km E-W × 12 km N-S) and azimuth of strain axes are compared to geological data and to other GPS results in central Greece. We find that strain in this region consists of an amount of shortening (66 ns/yr) in the direction approximately N 58°E, and about three times more extension (187 ns/yr) at N 32°W. A large change in strain orientation (from NW to NNE) is observed from west to east, along the active faults of Asopos rift in agreement with fault slip data. This change signifies the need for using local GPS networks to map local strain rate patterns in actively extending regions of Greece.
The Alto Tiberina Near Fault Observatory (northern Apennines, Italy)
Authors: Lauro Chiaraluce  , Alessandro Amato  , Simona Carannante  , Viviana Castelli  , Marco Cattaneo  , Massimo Cocco  , Cristiano Collettini  , Ezio D’Alema  , Raffaele Di Stefano  , Diana Latorre  , Simone Marzorati  , Francesco Mirabella  , Giancarlo Monachesi  , Davide Piccinini  , Adriano Nardi  , Antonio Piersanti  , Salvatore Stramondo  , Luisa Valoroso
Published: June 2021

The availability of multidisciplinary and high-resolution data is a fundamental requirement to understand the physics of earthquakes and faulting. We present the Alto Tiberina Near Fault Observatory (TABOO), a research infrastructure devoted to studying preparatory processes, slow and fast deformation along a fault system located in the upper Tiber Valley (northern Apennines), dominated by a 60 km long low-angle normal fault (Alto Tiberina, ATF) active since the Quaternary. TABOO consists of 50 permanent seismic stations covering an area of 120 × 120 km2. The surface seismic stations are equipped with 3-components seismometers, one third of them hosting accelerometers. We instrumented three shallow (250 m) boreholes with seismometers, creating a 3-dimensional antenna for studying micro-earthquakes sources (detection threshold is ML 0.5) and detecting transient signals. 24 of these sites are equipped with continuous geodetic GPS, forming two transects across the fault system. Geochemical and electromagnetic stations have been also deployed in the study area. In 36 months TABOO recorded 19,422 events with ML ≤ 3.8 corresponding to 23.36e-04 events per day per squared kilometres; one of the highest seismicity rate value observed in Italy. Seismicity distribution images the geometry of the ATF and its antithetic/synthetic structures located in the hanging-wall. TABOO can allow us to understand the seismogenic potential of the ATF and therefore contribute to the seismic hazard assessment of the area. The collected information on the geometry and deformation style of the fault will be used to elaborate ground shaking scenarios adopting diverse slip distributions and rupture directivity models.
Preface
Authors: Francesca Bianco  , Stefano Caliro  , Mario La Rocca  , Umberto Tammaro
Published: June 2021

Mt. Vesuvius is one of the most hazardous volcanoes in the world, due to the highly populated surrounding area, where more than 800,000 people live. It experienced various regimes of eruptive activity, from effusive to Plinian. Its last eruption, a mild effusive event, occurred on March 1944. After that the volcano started a period of quiescence, characterized by low seismicity, low deformation pattern, widespread fumaroles emissions accompanied by diffuse CO2 degassing in the crater area and CO2-rich groundwater along the southern flank and in the adjacent plain. Despite the low level of activity, Vesuvius is one of the best-monitored volcanoes in the world. During the last decades many researchers have been involved in the volcano monitoring, covering a wide range of topics, in order to discover any signals that could contribute to understand the volcano dynamics. However, in spite of so much effort, an exhaustive comprehension of the volcano system, aimed at a reliable prediction of the future activity, is far from having been reached. On the other hand, the fast technological evolution makes new instruments and methodologies available for a more sensitive monitoring in the future. [...]
Felt index, source parameters and ground motion evaluation for earthquakes at Mt. Vesuvius
Authors: Elena Cubellis  , Aldo Marturano
Published: June 2021

Results of non-instrumental surveys carried out on recent and past seismicity at Vesuvius have been retaken in order to propose new analyses regarding source mechanisms and causative faults. We present the results of the October 9, 1999, earthquake, the most intense event since the 1944 eruption. The intensity was evaluated by utilizing integer values of the MCS Scale and the felt index as a continuous parameter. Values of magnitude and attenuation determinated by applying macroseismic models to data, and compared to instrumental ones, were utilized to assess the “size” of the historical Vesuvian earthquakes. A magnitude of M = 5.1±.3 was considered for the A.D. 62 earthquake, the largest one of the area that preceded the A.D. 79 famous eruption. By using the macroseismic field of October 9, 1999, the source mechanism of the earthquake was obtained, and synthetic isoseisms and causative fault of the A.D. 62 are also proposed.
Groundwater geochemistry of the Mt. Vesuvius area: implications for volcano surveillance and relationship with hydrological and seismic signals
Authors: Cinzia Federico  , Paolo Madonia  , Paola Cusano  , Simona Petrosino
Published: June 2021

Geochemical data obtained between 1998 and 2011 at the Mt. Vesuvius aquifer are discussed, focusing on the effects of both the hydrological regime and the temporal pattern of local seismicity. Water samples were collected in a permanent network of wells and springs located in the areas that are mostly affected by the ascent of magmatic volatiles, and their chemical composition and dissolved gas content were analyzed. As well as the geochemical parameters that describe the behavior of groundwater at Mt. Vesuvius, we discuss the temporal distribution of volcano-tectonic earthquakes. The seismological data set was collected by the stations forming the permanent and mobile network of the Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano (INGV-OV). Our analysis of seismic data collected during 1998-2011 identified statistically significant variations in the seismicity rate, marked by phases of decreasing activity from October 1999 to May 2001 and increasing activity from August 2004 to mid-2006. The water chemistry shows peculiar patterns, characterized by a changeable input of CO2-rich and saline water, which must be related to either a changing stress field or an increased input of CO2-rich vapor. The water chemistry data from 1999 to 2003 account for both higher fluid pressure (which induced the seismic crisis of 1999 that peaked with a 3.6-magnitude earthquake in October 1999) and the increased input of CO2-rich fluids. The highest emission of CO2 from the crater fumaroles and the corresponding increase in dissolved carbon in groundwater characterize the phase of low seismicity. The termination of the phase of intense deep degassing is associated with a change in water chemistry and a peculiar seismic event that was recorded in July 2003. All these seismic and geochemical patterns are interpreted according to temporal variations in the regional and local stress field.
The seismic monitoring network of Mt. Vesuvius
Authors: Massimo Orazi  , Luca D’Auria  , Anna Tramelli  , Ciro Buonocunto  , Marco Capello  , Antonio Caputo  , Walter De Cesare  , Flora Giudicepietro  , Marcello Martini  , Rosario Peluso  , Giovanni Scarpato
Published: June 2021

Mt. Vesuvius (southern Italy) is one of the most hazardous volcanoes in the world. Its activity is currently characterized by moderate seismicity, with hypocenters located beneath the crater zone with depth rarely exceeding 5 km and magnitudes generally less than 3. The current configuration of the seismic monitoring network of Mt. Vesuvius consists of 18 seismic stations and 7 infrasound microphones. During the period 2006-2010 a seismic array with 48 channels was also operative. The station distribution provides appropriate coverage of the area around the volcanic edifice. The current development of the network and its geometry, under conditions of low seismic noise, allows locating seismic events with M<1. Remote instruments continuously transmit data to the main acquisition center in Naples. Data transmission is realized using different technological solutions based on UHF, Wi-Fi radio links, and TCP/IP client-server applications. Data are collected in the monitoring center of the Osservatorio Vesuviano (Italian National Institute of Geophysics and Volcanology, Naples section), which is equipped with systems for displaying and analyzing signals, using both real-time automatic and manual procedures. 24-hour surveillance allows to immediately communicate any significant anomaly to the Civil Protection authorities.
Volcanic precursors in light of eruption mechanisms at Vesuvius
Authors: Roberto Scandone  , Lisetta Giacomelli
Published: June 2021

Vesuvius entered a quiescent stage after the eruption of March-April 1944. The eruption was not much different or larger than other before, like for example the one of 1906, but it occurred at the end of a long period during which it was observed a decreasing trend of explosivity of eruptions [Scandone et al. 2008]. The parallel increase in the frequency of slow effusive eruptions, with respect to violent strombolian eruptions, point out to a process of average slower rate of magma ascent possibly due to a progressive sealing of the ascent path of magma to the surface. The small caldera collapse following the 1944 explosive phase effectively sealed the upper conduit, and since then the volcano entered a quiescence stage that was unusual with respect to the pattern of activity of the previous 300 years when the maximum repose time had been of 7 years (after the eruption of 1906). Most of the uncertainty on the duration of the present stage and character of a future renewal of activity derives by the basic questions regarding the nature of the current repose: due to a diminished supply of magma, related with structural condition or a sealing of the upper ascent path to the surface? Possibly the variation of structural conditions caused average slower ascent rates of magma favoring its cooling in the upper part of the crust, and effectively sealing the ascent path.
Acoustic ray tracing in the atmosphere: with gravitational effect and attenuation considered
Authors: Yang Song  , Yuannong Zhang  , Chen Zhou  , Zhengyu Zhao
Published: June 2021

An acoustic ray tracing model is developed to take into account the impacts of gravitational field and realistic atmospheric attenuation. Ray tracing equations are deduced from the real part of the dissipative dispersion relation, while the acoustic attenuation coefficient and growth rate in a stratified moving atmosphere are deduced from the imaginary part of the dispersion relation. To account for the non-isothermal effect and realistic attenuation, the buoyancy frequency and the cut-off frequency are substituted by the values in the slowly varying atmosphere, and the attenuation coefficient is corrected by the realistic absorption. In the validation by numerical experiment, the ray trajectory obtained by this ray tracing model agrees well with the result calculated by the FDTD method. It is shown that the acoustic trajectory can be accurately predicted by this ray tracing model. The numerical results for 5 Hz acoustic waves show that in the stratospheric ducting the gravitational effect plays a leading role while the attenuation effect could be neglected. But for the thermospheric ducting, the contribution of the absorption becomes more important.
New evidence on the geologic setting of Medjerda Valley plain (northern Tunisia) from integrated geophysical study of Triassic evaporite bodies
Authors: Amira Ayed-Khaled  , Taher Zouaghi  , Mohamed Atawa  , Mohamed Ghanmi
Published: June 2021

Integrated gravity, two dimensional (2D) seismic and field data (lithostratigraphy and tectonic deformations) help to understand the structural setting of the Triassic evaporites in the Atlas Mountains of northern Tunisia. In the Medjerda Valley plain, Triassic outcrops are bounded by NE-, ENE-, and NW-trending faults. These faults have been reactivated and have controlled the basin framework. The gravity analysis included the construction of a gravity anomaly maps, and 2D gravity model. Corresponding gravity responses of the complete Bouguer anomaly, the residual gravity anomaly, and upward continued maps reveal that the Triassic evaporites do not have a neat gravity signature. 2D seismic profiles show rising structures of Triassic strata associated with Mesozoic and Cenozoic tectonic edifices. The seismic horizons, calibrated to outcrop and well data, reveal paleohighs and diapirs of Triassic strata that were existed during the Jurassic and Early Cretaceous. These structural features induced a lateral outpouring of evaporitic strata within Late Cretaceous strata. A NW–SE-trending gravity model, which crosses the Medjerda Valley plain, highlights geometry identified on seismic lines. In the Medjerda plain, Mesozoic extensional and transtensional movements were associated with rising of Triassic evaporites, thus resulting in diapiric structures. The Late Cretaceous-Eocene structural setting was marked by outpouring of locally extruded Triassic evaporites. The Tertiary and Quaternary times are marked by major contractional events, causing inversion of pre-existing tectonic edifices. This integrated geophysical study provides a greater understanding of the Thibar deep structure, and a new geometry model of the Triassic evaporite bodies in the North Tunisia.
Ensemble Forecasting of Volcanic Emissions in Hawai’i
Authors: Andre Kristofer Pattantyus  , Steven Businger
Published: June 2021

Deterministic model forecasts do not convey to the end users the forecast uncertainty the models possess as a result of physics parameterizations, simplifications in model representation of physical processes, and errors in initial conditions. This lack of understanding leads to a level of uncertainty in the forecasted value when only a single deterministic model forecast is available. Increasing computational power and parallel software architecture allows multiple simulations to be carried out simultaneously that yield useful measures of model uncertainty that can be derived from ensemble model results. The Hybrid Single Particle Lagrangian Integration Trajectory and Dispersion model has the ability to generate ensemble forecasts. A meteorological ensemble was formed to create probabilistic forecast products and an ensemble mean forecast for volcanic emissions from the Kilauea volcano that impacts the state of Hawai’i. The probabilistic forecast products show uncertainty in pollutant concentrations that are especially useful for decision-making regarding public health. Initial comparison of the ensemble mean forecasts with observations and a single model forecast show improvements in event timing for both sulfur dioxide and sulfate aerosol forecasts. 

 
Volcanic Ash and SO2 retrievals using synthetic MODIS TIR data: comparison between inversion procedures and sensitivity analysis
Authors: Stefano Corradini  , Sergio Pugnaghi  , Alessandro Piscini  , Lorenzo Guerrieri  , Luca Merucci  , Matteo Picchiani  , Marco Chini
Published: June 2021

In this work the volcanic ash and SO2 retrievals obtained by applying three different procedures (LUT - Look Up Table, NN - Neural Network and VPR - Volcanic Plume Removal) on MODIS TIR synthetic measurements have been compared. The synthetic measurements are generated using MODTRAN RTM for defined volcanic cloud configurations. The results, presented as the percentage difference between the retrieved values and the true values used for the synthetic data generation, indicate maximum differences of +/- 15% and +/- 10% for all the procedures and for ash and SO2 retrievals respectively. A sensitivity analysis has been also realized to investigate the influence of volcanic cloud altitude and water vapour profile on SO2 retrievals at 7.3 and 8.6 micron. Results confirm the high sensitivity of the 7.3 micron retrieval to the volcanic cloud altitude and show that the SO2 total masses estimated at 7.3 and 8.6 micron separately can be used to improve the information on the volcanic cloud altitude. Finally, the water vapour profile is used to compute the minimum altitude over which the 7.3 m retrieval is effective.
Volcanic Ash Cloud Observation using Ground-based Ka-band Radar and Near-Infrared Lidar Ceilometer during the Eyjafjallajökull eruption
Authors: Frank S. Marzano  , Luigi Mereu  , Mario Montopoli  , Domenico Cimini  , Giovanni Martucci
Published: June 2021

Active remote sensing techniques can probe volcanic ash plumes, but their sensitivity at a given distance depends upon the sensor transmitted power, wavelength and polarization capability. Building on a previous numerical study at centimeter wavelength, this work aims at i) simulating the distal ash particles polarimetric response of millimeter-wave radar and multi-wavelength optical lidar; ii) developing and applying a model-based statistical retrieval scheme using a multi-sensor approach. The microphysical electromagnetic forward model of volcanic ash particle distribution, previously set up at microwaves, is extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena for both millimeter and optical bands. Monte Carlo generation of radar and lidar signatures are driven by random variability of volcanic particle main parameters, using constraints from available data and experimental evidences. The considered case study is related to the ground-based observation of the Eyjafjallajökull (Iceland) volcanic ash plume on May 15, 2010, carried out by the Atmospheric Research Station at Mace Head (Ireland) with a 35-GHz Ka-band Doppler cloud radar and a 1064-nm ceilometer lidar. The detection and estimation of ash layer presence and composition is carried out using a Bayesian approach, which is trained by the Monte Carlo model-based dataset. Retrieval results are corroborated exploiting auxiliary data such as those from a ground-based microwave radiometer also positioned at Mace Head.
Empirical relationships of shear wave velocity, SPT-N value and vertical effective stress for different soils in Mashhad, Iran
Authors: Azam Ghazi  , Naser Hafezi Moghadas  , Hosein Sadeghi  , Mohamad Ghafoori  , Gholam Reza Lashkaripur
Published: June 2021

Shear wave velocity, Vs, is one of the important input parameters in seismic response analysis of the ground. Various methods have been examined to measure the soil Vs directly. Direct measurement of Vs is time consuming and costly, therefore many researchers have been trying to update empirical relationships between Vs and other geotechnical properties of soils such as SPT Blow count, SPT-N. In this study the existence of a statistical relationship between Vs, SPT-N60 and vertical effective stress, signanu´, is investigated. Data set we used in this study was gathered from geotechnical and geophysical investigations reports. The data have been extracted from more than 130 numbers of geotechnical boreholes from different parts of Mashhad city. In each borehole the Vs has been measured by downhole method at two meter intervals. The SPT test also has performed at the same depth. Finally relationships were developed by regression analysis for gravels, sands and fine grain soils. The proposed relationships indicate that Vs is strongly dependent on signanu´. In this paper the effect of fine percent also is considered on the Vs estimation.
Neural network multispectral satellite images classification of volcanic ash plumes in a cloudy scenario
Authors: Matteo Picchiani  , Marco Chini  , Stefano Corradini  , Luca Merucci  , Alessandro Piscini  , Fabio Del Frate
Published: June 2021

This work shows the potential use of neural networks in the characterization of eruptive events monitored by satellite, through fast and automatic classification of multispectral images. The algorithm has been developed for the MODIS instrument and can easily be extended to other similar sensors. Six classes have been defined paying particular attention to image regions that represent the different surfaces that could possibly be found under volcanic ash clouds. Complex cloudy scenarios composed by images collected during the Icelandic eruptions of the Eyjafjallajökull (2010) and Grimsvötn (2011) volcanoes have been considered as test cases. A sensitivity analysis on the MODIS TIR and VIS channels has been performed to optimize the algorithm. The neural network has been trained with the first image of the dataset, while the remaining data have been considered as independent validation sets. Finally, the neural network classifier’s results have been compared with maps classified with several interactive procedures performed in a consolidated operational framework. This comparison shows that the automatic methodology proposed achieves a very promising performance, showing an overall accuracy greater than 84%, for the Eyjafjalla - jökull event, and equal to 74% for the Grimsvötn event. 
Volcanic SO2 by UV-TIR satellite retrievals: validation by using ground-based network at Mt. Etna
Authors: Claudia Spinetti  , Giuseppe Giovanni Salerno  , Tommaso Catalbiano  , Elisa Carboni  , Lieven Clarisse  , Stefano Corradini  , Roy Gordon Grainger  , Pascal Andre Hedelt  , Maria Elissavet Koukouli  , Luca Merucci  , Richard Siddans  , Lucia Tampellini  , Nicolas Theys  , Pieter Valks  , Claus Zehner
Published: June 2021

Mt. Etna volcano in Italy is one of the most active degassing volcanoes worldwide, emitting a mean of 1.7 Mt/year of Sulphur Dioxide (SO2) in quiescent periods. In this work, SO2 measurements retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS), hyper-spectral Infrared Atmospheric Sounding Interferometer (IASI) and the second Global Ozone Monitoring Experiment (GOME-2) data are compared with the ground-based data from the FLux Automatic MEasurement monitoring network (FLAME). Among the eighteen lava fountain episodes occurring at Mt. Etna in 2011, the 10 April paroxysmal event has been selected as a case-study for the simultaneous observation of the SO2 cloud by satellite and ground-based sensors. For each data-set two retrieval techniques were adopted and the measurements of SO2 mass and flux with their respective uncertainty were obtained. With respect to the FLAME SO2 mass of 4.5 Gg, MODIS, IASI and GOME-2 differ by about 10%, 15% and 30%, respectively. The SO2 flux correlation coefficient between MODIS and FLAME is 0.84. All the retrievals within the respective errors are in agreement with the ground-based measurements supporting the validity of these space measurements. 
Density-thermal dependence of sedimentary associations calls to reinterpreting detailed gravity surveys
Authors: Vagif G. Gadirov  , Lev V. Eppelbaum
Published: June 2021

The modern gravimetric equipment allows to register very small effects of gravity field changes and can be applied solving different geological, geophysical and environmental problems. However, sometimes insufficient calculation of various kinds of geological noise complicates effective application of detailed gravity field analysis. One of such factors is the temperature regime over and outside different buried objects of investigation. In this paper temperature changes in a subvertical zone over a hydrocarbon deposit and outside its contour are analyzed. The integrated density change and corresponding gravity effects are calculated for the Muradkhanly oil deposit situated within the south-east part of the Middle Kura Depression (central Azerbaijan). Calculation of these effects on the basis of density- temperature data correlation analysis could significantly improve the microgravity field examination over the hydrocarbon deposits. The similar correction procedure may be applied also over underground water horizons and some environmental targets.
Background electromagnetic noise characterization: the role of external and internal Earth sources
Authors: Antonio Meloni  , Cesidio Bianchi  , Giuliana Mele  , Paolo Palangio
Published: June 2021

The Earth is surrounded by the ionosphere and magnetosphere that can roughly be seen schematically as two concentric shells. These two composed and inhomogeneous structured shells around the Earth selectively affect electromagnetic (EM) waves propagation. Both ionosphere and magnetosphere interact also with particles and waves coming from external sources, generating electromagnetic phenomena that in turn might become sources of EM waves. Conversely, EM waves generated inside the ionosphere remain confined at various altitudes in this region, up to a so-called critical frequency limit, depending on frequency, EM waves can escape out of the ionosphere and magnetosphere or get through. The EM waves generated inside the magnetospheric cavity mainly originate as a result of the electrical activity in the atmosphere. It is well known that also man-made sources, now widely spread on Earth, are a fundamental source of EM waves; however, excluding certain frequencies employed in power distribution and communication, man-made noise can be dominant only at local scale, near their source. According to recent studies, EM waves are also generated in the Earth’s lithosphere; these waves were sometimes associated with earthquake activity showing, on the Earth’s surface, intensities that are generally orders of magnitude below the background EM noise. In this review paper, we illustrate EM waves of natural origin and discuss their characterization in order to try discriminate those of lithospheric origin detectable at or near the Earth’s surface.
The first ultra-high resolution Digital Terrain Model of the shallow-water sector around Lipari Island (Aeolian Islands, Italy)
Authors: Alessandro Bosman  , Daniele Casalbore  , Marco Anzidei  , Filippo Muccini  , Cosmo Carmisciano  , Francesco Latino Chiocci
Published: June 2021

 

Very high resolution bathymetric map obtained through multibeam echo-sounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultra-high resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters.
New insight into the 2011-2012 unrest and eruption of El Hierro Island (Canary Islands) based on integrated geophysical, geodetical and petrological data
Authors: Stavros Meletlidis  , Alessio Di Roberto  , Itahiza Domínguez Cerdeña  , Massimo Pompilio  , Laura García-Cañada  , Antonella Bertagnini  , Maria Angeles Benito-Saz  , Paola Del Carlo  , Sergio Sainz-Maza Aparicio
Published: June 2021

A shallow water eruption started on October 10, 2011, ~2 km south off the coast of El Hierro (Canary Islands, Spain). The eruption lasted about five months and ended by early March 2012. Three months of unrest preceded this event with more than 10,000 localized earthquakes and up to 6 cm of vertical ground deformation. In the Canary Islands, this is the first eruption to be monitored by the network of Instituto Geográfico National (IGN) since the very beginning of the seismic unrest. This provided unprecedented time series that include geophysical (seismic and gravimetric), geodetic, geochemical and petrological data. In this work we discuss and interpret these data in order to describe the mechanisms of 2011-2012 El Hierro eruption, including ascent from magmatic source, a crustal storage, and the final intrusion in the South Rift before the eruption. Our research approach provides a multidisciplinary view of the dynamics of magma ascent and improves previous interpretations formulated during or shortly after the end of the eruption. According to our results, a major intrusion occurred beneath and around preexisting high-density magmatic bodies, localized at depth below the central part of the island. After a failed attempt to reach the surface through a low fractured zone located below the central-northern part of the island, the ascending magma finally found its way nearby the El Hierro South Rift Zone and erupted off the coast of La Restinga village, 350 m below sea level. The eruption was fed by the ascent of an important volume of material from the upper mantle that was emplaced near the crust-mantle boundary and progressively tapped during the eruption.
Annex to: Volcanic Ash Cloud Observation using Ground-based Ka-band Radar and Near-Infrared Lidar Ceilometer during the Eyjafjallajökull eruption
Authors: Frank S. Marzano  , Luigi Mereu  , Mario Montopoli  , Domenico Cimini  , Giovanni Martucci
Published: June 2021

Volcanic ash plumes are formed during explosive volcanic eruptions. After advection over several thousands of kilometers, volcanic ash particles are highly fragmented, dispersed and aged with micron- sized sorting. This Annex describes the ash microphysical modeling and the simulated radar and lidar signatures. [...]
Geomagnetic coast effect at two Croatian repeat stations
Authors: Eugen Vujić  , Mario Brkić
Published: June 2021

Knowledge of inductive effects is important for the reliability of geomagnetic surveys as well as reduction of measurements, and hence for the accuracy of models and maps of the Earth’s magnetic field. Detection of anomalous induced fields, due to the geomagnetic coast effect, was carried out by the transfer function method to estimate the induction arrows indicating areas of anomalous induced currents. To determine the transfer function at the two coastal Croatian repeat stations used in this study, the so-called geomagnetic plane-wave events from July 2010 were used. Analysis of transfer functions for Krbavsko polje and Sinjsko polje first order repeat stations, using observatories Grocka and Tihany as references, revealed the existence of the Adriatic coastal effect on periods of 10-65 minutes.
DE-1 versus Cluster spectral density observations: the effect on ion outflow above the polar cap
Authors: Hamza A. Abudayyeh  , Imad A. Barghouthi  , Ghadeer Al-Sarsour  , Husain Alsamamra
Published: June 2021

Wave-particle interaction is a very important mechanism in describing the outflow of ions at high latitudes and high altitudes. Quasi-linear perpendicular velocity diffusion coefficients are used to describe the effect of wave-particle interactions, therefore it is essential to determine the correct diffusion coefficients that must be used to model the outflow of ions. In this study a Monte Carlo method is used to assess the role of different diffusion coefficients for O+ and H+ ions at high altitudes above the polar cap. Two different sets of diffusion coefficients obtained from Barghouthi [1997]; Barghouthi et al. [1998] and Nilsson et al. [2013] are used. Barghouthi [1997]; Barghouthi et al. [1998] used spectral density measurements from Dynamic Explorer 1 spacecraft (DE-1) observations to calculate the diffusion coefficients, while Nilsson et al. [2013] used spectral density measurements from the Cluster spacecraft to obtain the diffusion coefficients. It was found that diffusion coefficients from Barghouthi [1997]; Barghouthi et al. [1998] in the cusp (aurora) and central polar cap (polar wind) respectively, describe well the observations of ion outflow at altitudes lower than 5 RE, but yield unreasonably high parallel velocities and temperatures at higher altitudes. Also diffusion coefficients from Cluster spectral density measurements produce reasonable results for high altitudes and unreasonably low parallel velocities and temperatures for the low altitude region. Therefore it is suggested that a combination of these diffusion coefficients is used where the diffusion coefficients given by Barghouthi [1997]; Barghouthi et al. [1998] are used at low altitudes and the diffusion coefficients obtained from Cluster measurements are used at high altitudes.
Geometric quality term for station-based total electron content estimation
Authors: Murat Selim Çepni  , Erman Şentürk
Published: June 2021

Global ionospheric maps (GIMs) are still commonly used to represent total electron content (TEC). However, a large number of permanent GPS receivers provide significant data for monitoring ionosphere. The GIMs supply accurate TEC results, although spherical models are not able to fit local ionospheric perturbations as a source of local receiver data. Therefore, the use of station-based TEC computation becomes more preferred and convenient. The station-based TEC approach is established on weighting averaging or modeling vertical TECs. Using this approach to reveal ionospheric activity depends on geometric distribution of ionospheric piercing points (IPP). The most effective parameter for examination of station-based TEC estimation is a function of relative geometry between receiver and satellite. In this study, a quality term has been used to define, for TEC estimation according to distribution of IPPs, similar to geometric dilution of precision (GDOP). The quality term has been described for the first time in this field and it was named as R-TEC (reliability of total electron content).
The local ionospheric modeling by integration ground GPS observations and satellite altimetry data
Authors: Mohammad Ali Sharifi  , Saeed Farzaneh
Published: June 2021

The free electrons in the ionosphere have a strong impact on the propagation of radio waves. When the signals pass through the ionosphere, both their group and phase velocity are disturbed. Several space geodetic techniques such as satellite altimetry, low Earth orbit (LEO) satellite and very long baseline interferometry (VLBI) can be used to model the total electron content. At present, the classical input data for development of ionospheric models are based on dual-frequency GPS observations, However, a major problem with this observation type is the nonuniform distribution of the terrestrial GPS reference stations with large gaps notably over the sea surface and ocean where only some single stations are located on islands, leading to lower the precision of the model over these areas. In these regions the dual-frequency satellite altimeters provide precise information about the parameters of the ionosphere. Combination of GPS and satellite altimetry observations allows making best use of the advantages of their different spatial and temporal distributions. In this study, the local ionosphere modeling was done by the combination of space geodetic observations using spherical Slepian function. The combination of the data from ground GPS observations over the western part of the USA and the altimetry mission Jason-2 was performed on the normal equation level in the least-square procedure and a least-square variance component estimation (LS-VCE) was applied to take into account the different accuracy levels of the observations. The integrated ionosphere model is more accurate and more reliable than the results derived from the ground GPS observations over the oceans.
Ionospheric perturbations related to the earthquake in Vrancea area on November 22, 2014, as detected by electromagnetic VLF/LF frequency signals
Authors: Maria Solovieva  , Alexander Rozhnoi  , Viktor Fedun  , Konrad Schwingenschuh  , Masashi Hayakawa
Published: June 2021

Data from the European network of very low/ low frequency (VLF/LF) receivers has been used to study the response of the lower ionosphere to the earthquake of magnitude 5.5 in Vrancea area on November 22, 2014. Negative amplitude anomalies have been observed during 3 days before the earthquake and two days after, on the LF (45.9 kHz) signal passed above the seismic area. No perturbations have been found for the same signal in control paths during this period. Other possible influences both from above and below which can produce perturbations in the ionosphere have been taken into consideration.
A new MD-ML relationship for Mt. Etna earthquakes (Italy)
Authors: Tiziana Tuvè  , Salvatore D'Amico  , Elisabetta Giampiccolo
Published: June 2021

A homogenous database of magnitude observations is a basic requirement for seismic hazard estimation and other seismic studies. Unfortunately, the magnitude reported in the seismic catalogue of Mt. Etna is not homogenous.  Until 2005 only the duration magnitude (MD) is available, though since then the more stable local magnitude (ML) has also been calculated. To overcome this limitation, earthquake data recorded at Mt. Etna during the period 2005 – 2014 were used to derive a new relationship between local and duration magnitude, by applying the General Orthogonal Regression (GOR) which is an alternative to least squares when the ratio between errors on the independent and the dependent variables can be estimated. The relationship obtained is:

     ML = 1.164 (± 0.011) * MD - 0.337 (± 0.020)                                          

 The new relationship allows to back-extend the local magnitude dataset to cover a period of about 15 years.