bluuebunny/crossref_metadata_2025 huggingface dataset:
Computation of improved tidal parameters at the gravimetric station of Brasimone
Authors: G. Casula  , P. Baldi
Published: June 2021

Since 1991 a GWR superconducting gravimeter has been working in a laboratory at the Brasimone ENEA Research Centre, near Bologna (Italy), in the frame of an experimental program to verify Newton's law over distances of the order of 10-100 m. Owing to the aim of the experiment, the gravimeter was moved to different laboratories in the same area, but from August 1995 to date it has been working continuously in the same laboratory in the frame of the preliminary program of the Global Geodynamics Project. The site, belonging to a building of a dismissed nuclear power plant, is free from noise due to human activities, and is thus highly suitable for recording Earth tides. Starting from a set of gravimetric and atmospheric pressure data of high quality relative to 22 months of observation, we performed the tidal analysis using Eterna 3.2 software in order to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura 1987 catalogue. The accuracy of the method adopted for the calibration of the gravimeter, the values of the principal waves and the result of the computation of atmospheric pressure admittance are described.
On the origin of medium-period ionospheric waves and their possible modelling: a short review
Authors: P. Dominici  , L. R. Cander  , B. Zolesi
Published: June 2021

This article introduces the concept of ionospheric waves with periods from about 15 min to about 4 h as one of the acoustic-gravity wave-induced phenomena. The existence of these medium-period ionospheric waves in the various ionospheric layers is supported by the results of a data analysis which has shown remarkable characteristics in occurrence and direction of the waves with a period not longer than about 2 h. The explanation offered is based on the assumption that a unique phenomenon capable to launch acoustic-gravity waves related to such ionospheric waves is the sudden change in physical conditions of the atmosphere due to the passage of the solar terminator.
Real-time monitoring of seismic data using satellite telemetry
Authors: G. Calderoni  , B. De Simoni  , F. M. De Simoni  , L. Merucci
Published: June 2021

This article describes the ARGO Satellite Seismic Network (ARGO SSN) as a reliable system for monitoring, collection, visualisation and analysis of seismic and geophysical low-frequency data, The satellite digital telemetry system is composed of peripheral geophysical stations, a centraI communications node (master sta- tion) located in CentraI Italy, and a data collection and processing centre located at ING (Istituto Nazionale di Geofisica), Rome. The task of the peripheral stations is to digitalise and send via satellite the geophysical data collected by the various sensors to the master station. The master station receives the data and forwards them via satellite to the ING in Rome; it also performs alI the monitoring functions of satellite communications. At the data collection and processing centre of ING, the data are received and analysed in real time, the seismic events are identified and recorded, the low-frequency geophysical data are stored. In addition, the generaI sta- tus of the satellite network and of each peripheral station connected, is monitored. The procedure for analysjs of acquired seismic signals allows the automatic calculation of local magnitude and duration magnitude The communication and data exchange between the seismic networks of Greece, Spain and Italy is the fruit of a recent development in the field of technology of satellite transmission of ARGO SSN (project of European Community "Southern Europe Network for Analysis of Seismic Data" )
Georesistivity precursors to the Tangshan earthquake of 1976
Authors: F. Qian  , B. Zhao  , F. Lu
Published: June 2021

Georesistivity precursors and corresponding coseismic effects to the Tangshan earthquake of 1976 are given as follows: 1) resistivity measurements with accuracies of 0.5% or better for over 20 years show that resistivity decreases of several percent, which began approximately 3 years prior to the Tangshan earthquake, were larger than the background fluctuations and hence statistically significant. An outstanding example of an intermediate-term resistivity precursor is given. 2) Georesistivity decreases of several percent observed simultaneously at 9 stations beginning 2-3 years prior to the 1976 Tangshan earthquake are such a pervasive phenomenon that the mean decrease, in percent, can be contoured on a map of the Beijing-Tianjin-Tangshan region. This shows the maximum decrease centered over the epicenter. 3) Corresponding coseismic resistivity changes, ??c/?c, during the M 7.8 Tangshan earthquake were observed at all 16 stations within 240 km from the epicentre. These observed ??c/?c are opposite in sense but similar in spatial distribution to corresponding georesistivity precursors. This observation suggests that the Tangshan earthquake is a rebound process. Calculation indicates that these georesistivity precursors could be represented by a virtual dislocation, of opposite sign to the real dislocation produced at the time of the Tangshan earthquake. These reported ??c/?c offer very convincing evidence for accepting corresponding anomalies prior to the earthquake as its precursors. 4) It is inferred from observed anisotropic decreases in georesistivity that before the Tangshan earthquake the crust was compressed and that the angle between the maximum principal stress ?1 and the earthquake fault was about 80° before the earthquake i.e., the fault was locked by the ?1 which is almost normal to the fault.
Preliminary objective regionalization of the Mediterranean basin derived from surface-wave tomography
Authors: M. D. Martínez  , X. Lana  , J. Badal  , J. A. Canas  , L. Pujades
Published: June 2021

An objective regionalization of the Mediterranean basin is derived from a tomographic study based on the fundamental mode of Rayleigh waves. The database is formed by seismic wavetrains recorded at very-broadband stations belonging to MedNet and other cooperative stations, located in the Mediterranean area. The data treatment consists of application of spectral filtering techniques aimed to determine path-averaged group velocities, computation of local group velocity maps for some periods and classification of the studied area in several homogeneous regions according to Principal Component Analysis (PCA) and Average Linkage (AL) algorithms. Finally, the group velocity dispersion curves representing each homogeneous region are compared and possible correlation between these regions and seismotectonic and structural characteristics are discussed.
A proper methodology aimed at surface wave tomography
Authors: F. J. Sabadell  , F. J. Serón  , J. Badal
Published: June 2021

When applying a methodology for obtaining the 3D shear-wave velocity structure of a medium from surface wave dispersion data, the problem must be considered with caution since one inverts path-averaged velocities and the use of any inversion method entails some drawbacks such as lack of uniqueness, unwarranted stability and constraints affecting the data. In order to avoid the application of consecutive inversions and to overcome these drawbacks, we propose alternative mapping methods, for example spatial prediction methods, or else the use of an algorithm that, from a mathematical viewpoint, can be understood through the application of the orthogonal projection theorem onto convex sets (POCS). Among the first ones, we try inverse weighted distance interpolation. The POCS algorithm we have used discretises a second order differential equation for the velocity field with boundary conditions. All these imaging techniques aimed at volumetric modelling and the visualisation of data are discussed, and finally we show some results based on ray path velocities obtained previously by inversion of phase and group velocities of Rayleigh waves propagating across the Iberian peninsula.
Global volcanic earthquake swarm database and preliminary analysis of volcanic earthquake swarm duration
Authors: J. P. Benoit  , S. R. McNutt
Published: June 2021

Global data from 1979 to 1989 pertaining to volcanic earthquake swarms have been compiled into a custom-designed relational database. The database is composed of three sections: 1) a section containing general information on volcanoes, 2) a section containing earthquake swarm data (such as dates of swarm occurrence and durations), and 3) a section containing eruption information. The most abundant and reliable parameter, duration of volcanic earthquake swarms, was chosen for preliminary analysis. The distribution of all swarm durations was found to have a geometric mean of 5.5 days. Precursory swarms were then separated from those not associated with eruptions. The geometric mean precursory swarm duration was 8 days whereas the geometric mean duration of swarms not associated with eruptive activity was 3.5 days. Two groups of precursory swarms are apparent when duration is compared with the eruption repose time. Swarms with durations shorter than 4 months showed no clear relationship with the eruption repose time. However, the second group, lasting longer than 4 months, showed a significant positive correlation with the log10 of the eruption repose period. The two groups suggest that different suites of physical processes are involved in the generation of volcanic earthquake swarms.
Structural and seismological segmentation of the Gulf of Corinth fault system: implications for models of fault growth
Authors: G. P. Roberts  , I. Koukouvelas
Published: June 2021

The positions and dimensions of fault segments within the Gulf of Corinth fault system have been identified by analysing spatial variation in fault displacements and fault kinematics. Growth of these fault segments is assessed by comparing their geometry and kinematics with the geometry and kinematics of the three sets of earthquake surface ruptures that are known to have affected the area in the last -200 years. Areas along the Gulf of Corinth fault system exhibiting low fault displacement (tens of metres) are identified as persistent segment boundaries which separate the fault system into a number of fault segments characterised by displacements which achieve maxima of -3 km. Fault-slip directions defined by lineations on fault planes vary systematicalIy with fault displacement, showing a converging pattem towards the hanging-walls of the fault segments: the fault-slip directions change by -90° across persistent segment boundaries. It is unclear where fault segments end and persistent segment boundaries begin, but if the persistent segment boundaries are considered to be -10-15 km across, the intervening fault segments achieve lengths of 30-35 km. In contrast known surface ruptures during the last -200 years, including those for the 1995 Egion earthquakes, have all been < 15 km in Length. these so-caIled earthquake segmens are, therefore, considerably shorter than the fault segmentss that hosted the earthquakes. Also, the positions of earthquake segments have varied relative to the positions of the fault segments during successive earthquakes. It appears, therefore, that a Modified Overlap Model is more appropriate than the Characteristic Earthquake Model to describe the seismological behaviour of fault segments around the Gulf of Corinth through a number of earthquake cycles. A pattern of coseismic slip vectors converging towards the hanging-wall has been measured for the surface ruptures to 1995 Egion earthquakes; a similar pattern was noted for the 1981 Alkyonides earthquake ruptures. Repetition of such ruptures in different positions along fault segments, in accordance with a Modified Overlap Model, will produce systematic variations in the scatter of fault-slip directions, with fault displacement. Thus, scatter in the orientations of lineations on fault planes may contain information concerning the lengths and positions of numerous pre-historic earthquake segments; information which may be used to constrain both the palaeoseismology and the future seismjcity in areas of active extension.
Spectral analysis of the f0F2 data obtained at five PRIME sites during a 15 minute campaign in June 1993
Authors: Y. Tulunay  , S. A. Baykal  , Y. G. Yigit  , I. Stanislawska  , A. Rokicki  , Z. Zbyszynski  , A. Özgüc  , T. Atac  , L. Altas  , O. Barlas
Published: June 2021

During the COST 238: PRIME project there was a campaign of 15-min intervals of the f0F2 soundings at Kandilli, Rome, Sofia, Poitiers and Lannion. The campaign took place for one month in June 1993. The spectral analysis of the data using a Fast Fourier Transform (FFT) algorithm proved a relatively easy method to reconstruct the original data at the confidence level = 0.05.
Mid-latitude ionosphere during two great geomagnetic storms
Authors: I. M. Vasiljevic  , L. R. Cander
Published: June 2021

The ionospheric disturbances observed at many European ionosonde stations in association with the severe geomagnetic storms occurring on 19-20 December 1980 and 11-12 April 1981 were investigated by using the available ionospheric and geomagnetic data. During these storms the ionospheric F region underwent major changes at all mid-latitudes. However, the variations from storm to storm were much larger at lower mid-latitudes. These results support the view that even in assessing the response of the mid-latitude ionosphere to severe geomagnetic storms it is necessary to distinguish carefully between global, regional and local behaviour.
Modelling of the electron density height profiles in the mid-latitude ionospheric D-region
Authors: D. V. Pancheva  , P. Y. Mukhtarov
Published: June 2021

A new mid-latitude D-region (50-105 km) model of the electron density is presented obtained on the basis of a full wave theory and by a trial-and-error inversion method. Daytime (at different solar zenith angles) absorption measurements by A3-technique made in Bulgaria yielded data with the aid of which the seasonal and diurnal courses of the Ne(h)-profiles were derived. Special attention is drawn to the event diurnal asymmetry, or uneven formation of the ionosphere as a function of insulation. The latter is probably connected with the influence of the diurnal fluctuations in the local temperature on the chemistry involved in the electron loss rate, as well as the diurnal variations of the main ionizing agent (NO) in the D-region. That is why the Ne(h)-profiles in the midlatitude D-region are modelled separately for morning and afternoon hours.
A steady-state F-region model and its use for satellite data analysis
Authors: S. M. Stankov
Published: June 2021

A steady-state mathematical model of the Earth's upper ionosphere and plasmasphere is presented. In the model the equations of continuity, momentum, and energy balance for O+, H+, and He+ ions are solved numerically along dipole magnetic field lines. As an extension of the model, a searching method is developed for de- termination of the boundary values in a self-consistent manner. Model results are compared with Atmosphere Explorer satellite measurements.
Evidence for a geomagnetic jerk in 1990 across Europe
Authors: L. Cafarella  , A. Meloni
Published: June 2021

The analysis of geomagnetic data from magnetic observatories demonstrated the existence of very rapid changes, or jerks, in the secular variation, especially the occurrence of the well known geomagnetic jerks of 1969 and 1978. A new geomagnetic jerk seems to have appeared around 1990 and is clearly visible at a selec- tion of European magnetic observatories as a rapid and sudden change in the secular variation pattern. The comparison between all day and quiet day means for two different observatories, respectively at high and middle latitude, suggests that this phenomenon, as stated by many authors for the other jerks, could be generated by an internal source.
Geoelectric and electromagnetic measurements within an organized archaeological framework: the Marzabotto example
Authors: E. Bozzo  , S. Lombardo  , F. Merlanti  , M. Pavan
Published: June 2021

Geophysical prospecting was Performed in the Etruscan settlement of Marzabotto, near Bologna (Italy), to find shallow anthropic structures within an almost homogeneous environment. This paper describes some results of the geoelectric and electromagnetic VLF methods used. Non-standard geoelectric devices, such as the tripotential, twin-probe and the Offset-Wermer methods, were applied. The set of results was compared to classical dipolar sections. The Offset-Wenner device was useful for detecting vertically striking structures. Conversely, the electromagnetic VLF techniques are not suitable for investigating structures with a negligible contrast of conductivity with the environment. Prospecting data generated a general pattern of anomalies and some were confirmed by excavation samples, showing walIs, floors, water wells and other remains of urban structures.
Seismic modeling of two depositional systems
Authors: G. Brancolini  , G. Casula  , C. De Cillia  , A. Manzella  , A. Polonia  , M. Rebesco  , G. Seriani
Published: June 2021

Two ideal lithologic sections representing a tidal bar system and a fluvial complex were drawn in order to run seismic modeling programs developed by OGS on behalf of the European Community. The simulations allowed an accurate analysis of the seismic expressions of the two sections. The tidal bar system is formed by a number of sandstone lenses interlayered with siltstone and mudstone deposits. These lenses meet together on an erosion surface, while they thin and vanish in the other direction. The fluvial complex is fonned by a limestone basement overlain by coarse alluvial plain sediments which in turn are transgressed by finer flood plain sediments, including sandstone lenses stacking towards the top in a meandering belt. These lithofacies associations represent potential multi-pool reservoirs in which the mudstone layers constitute the plugs. As a function of the granulometric and depositional features of each lithological unit, together with fluid content, wave velocities and densities were evaluated. A 2D modeling for elastic plane wave propagation in these hypothesized geologic sections was run on a Cray supercomputer. The numerical scheme is based on solving the full wave equation by pseudospectral methods.
Detection capability of the Italian network for teleseismic events
Authors: R. Di Maro  , A. Marchetti
Published: June 2021

The future GSE experiment is based on a global seismic monitoring system, that should be designed for monitoring compliance with a nuclear test ban treaty. Every country participating in the test will transmit data to the International Data Center. Because of the high quality of data required, we decided to conduct this study in order to determine the set of stations to be used in the experiment. The Italian telemetered seismological network can detect all events of at least magnitude 2.5 whose epicenters are inside the network itself. For external events the situation is different: the capabilíty of detection is conditioned not only by the noise condition of the station, but also by the relative position of epicenter and station. The ING bulletin (January 1991-June 1992) was the data set for the present work. Comparing these data with the National Earthquake Information Center (NEIC) bulletin, we established which stations are most reliable in detecting teleseismic events and, moreover, how distance and back-azimuth can influence event detection. Furthermore, we investigated the reliability of the automatic acquisition system in relation to teleseismic event detection.
A single-station prediction model as a contribution to instantaneous mapping
Authors: I. Stanislawska
Published: June 2021

The paper presents two opposite approaches for single-station prediction and forecast. Both methods are based on different assumptions of physical processes in the ionosphere and need the different set of incoming data. Different heliogeophysical data, mainly f0F2 parameters from the past were analyzed for f0F2 obtaining for the requested period ahead. In the first method - the autocovariance prediction method - the time series of f0F2 from one station are used for daily forecast at that point. The second method may be used for obtaining f0F2 not only at the particular ionospheric station, but also at any point within the considered area.
Three years of high precision gravity measurements at the gravimetric station of Brasimone - Italy
Authors: G. Casula
Published: June 2021

From August 1995 up to now, at the Enea Research Center of Brasimone, in the Italian Apennines between Bologna and Florence (Italy: 44º07'N, 11º.07'E, 890 m height), the superconducting gravimeter GWR model TT70 number T015 has been continuously recording the variation of the local gravity field, in the frame of the Global Geodynamics Project. The gravimetric laboratory, being a room of the disused nuclear power plant of Brasimone, is a very stable site, free from noise due to human activities. Data blocks of several months of continuous gravity records have been collected over a time span of three years, together with the meteorological data. The gravimeter has been calibrated at relative accuracy better than 0.3% with the aid of a mobile mass system, by imposed perturbations of the local gravity field and recording the gravimeter response. The results of this calibration technique were checked by two comparison experiments with absolute gravimeters performed during this period: the first, in May 1994 with the aid of the symmetrical rise and fall gravimeter of the Institute of Metrology Colonnetti of Turin, and the second in October 1997 involving an FG5 absolute gravimeter of the Institute de Physique du Globe of Strasbourg. The gravimeter signal was analysed to compute a high precision tidal model for Brasimone site. Starting from a set of gravimetric and atmospheric pressure data of high quality, relative to 46 months of observation, we performed the tidal analysis using Eterna 3.2 software to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura catalogue. Finally a comparison experiment between two of the STS-1/VBB broadband seismometers of the MedNet project network and the gravity records relative to the Balleny Islands earthquake (March 25, 1998) were analysed to look for evidence of normal modes due to the free oscillations of the Earth.
Spatial distribution of horizontal seismic strain in the Apennines from historical earthquakes
Authors: G. Selvaggi
Published: June 2021

Horizontal principal seismic strain rate axes have been calculated within a regular mesh of triangles covering the Italian peninsula in a time interval of 700 years. I have used both the method of Kostrov (1974), that requires knowledge of the seismic moment tensor of earthquakes, and the modified version provided by England and Molnar (1997) that makes use of length and kinematics of the activated faults. Seismic moment tensor of historical earthquakes can be inferred from recent literature, while length of faults has been obtained from the observation that strain drop is almost constant for large Apenninic earthquakes. Spatial strain distribution from historical earthquakes shows that the Apennines can be divided into three homogeneous structural arcs (Northern Apenninic, Southern Apenninic and Calabrian arcs) within which strain is roughly constant. Although NE-SW extension is the main deformation process along the two Apenninic arcs it involves a velocity more than five times greater in the Southern Apennines. Along the Calabrian arc, I tested the effect on the strain field of the contemporaneous ~WNW-ESE and ~NNE-SSW extension due to the longitudinal dilatation of the arc during its still ESE migration.
Modelling of karst structures by geophysical methods. An example: the doline of S. Pietro dei Monti (Western Liguria)
Authors: E. Armadillo  , F. Massa  , G. Caneva  , M. Gambetta  , E. Bozzo
Published: June 2021

Integrated geophysical investigations of karst structures were carried out in Liguria and Piedmont (NW Italy); this paper refers to the S. Pietro dei Monti doline, in the karst area of Mt. Carmo (Savona). The techniques used in the integrated study were magnetics, electromagnetics and seismic refraction. The target was to identify, without drilling, the nature of the doline, for example if it is of dissolution or collapse type. A preliminary susceptibility sampling of the outcrop and topsoil and the diffuse fractures with a probable water seepage suggested magnetics and VLF electromagnetics. Such methods applied in an area with an extremely low cultural noise allowed modelling of the buried structure of the doline.
A test site for the magnetic detection of buried steel drums
Authors: M. Marchetti  , M. Chiappini  , A. Meloni
Published: June 2021

An environmental investigation test site for the application of magnetic techniques to detect buried steel drums was performed in Central Italy. A magnetic survey was carried out on the area of the test site, where 12 steel drums had previously been buried. The survey was performed by means of a proton precession magnetometer for total field measurements in single sensor as well as in gradiometer configurations. The experiment has led to the definition of the magnetic signature of vertically oriented drums buried at 4.5 m below ground level. A digitally enhanced magnetic anomaly map was then produced, allowing further modelling procedures. Data reduction, processing procedures and results are presented.
New geomagnetic measurements in the Republic of Macedonia
Authors: Marjan Delipetrev  , Nenad Novkovski  , Todor Delipetrov
Published: June 2021

This study presents measurements of the geomagnetic field of the Republic of Macedonia, performed through a network of newly defined repeat stations. The measurements of these elements were in the intervals of 3.378° ≤ DD ≤ 3.983°, 57.276° ≤ I ≤ 59.005°, and 46 235 nT ≤ F ≤ 46903 nT. The geomagnetic data were processed and the results of the observed elements of the geomagnetic field on the repeat stations are presented. Additional data processing was performed to calculate the reduced values of the intensive elements of the field at the level of H500 a.s.l.. Based on these data, new maps of the geomagnetic field of the Republic of Macedonia are developed, together with the polynomial model of the elements of the geomagnetic field for the 2010.0 epoch.
Relaxation phenomena of electrical signal emissions from rock following application of abrupt mechanical stress
Authors: Dimos Triantis  , Filippos Vallianatos  , Ilias Stavrakas  , George Hloupis
Published: June 2021

The emission of electrical signals during application of mechanical stress to brittle geo-materials (the so-called pressure-stimulated current; PSC) can provide significant information regarding the mechanical status of a studied rock sample. PSCs originate as a result of the opening of cracks and microfractures in rock. In this study, such electrical signal emissions are detected and studied when rock samples are subjected to step-wise mechanical stress, increased from low stress levels vL up to higher stress levels vH. This increase is performed at high stress rates and consequently the stress is maintained practically constant for a long period. During this time, the applied stress reaches its maximum value, and the emitted PSC decays gradually and relaxes back to a minimum value. The conducted experiments suggest that the characteristics of the relaxation processes of the PSC depend directly on the high level of the applied stress that is maintained constant after the application of each stress step. Analysis of the macroscopic parameters that characterize the relaxation phenomenon of the PSC provides clear information regarding the proximity of the applied stress to the fracture limit of the rock sample.
Comparison of the reference mark azimuth determination methods
Authors: Danijel Šugar  , Mario Brkić  , Drago Špoljarić
Published: June 2021

The knowledge of the azimuth of the reference mark is of crucial importance in the determination of the declination which is defined as the ellipsoidal (geodetic) azimuth of the geomagnetic meridian. The accuracy of the azimuth determination has direct impact on the accuracy of the declination. The orientation of the Declination-Inclination Magnetometer is usually carried out by sighting the reference mark in two telescope faces in order to improve the reliability of the observations and eliminate some instrumental errors. In this paper, different coordinate as well as azimuth determination methods using GNSS (Global Navigation Satellite System) observation techniques within VPPS (High-Precision Positioning Service) and GPPS (Geodetic-Precision Positioning Service) services of the CROPOS (CROatian POsitioning System) system were explained. The azimuth determination by the observation of the Polaris was exposed and it was subsequently compared with the observation of the Sun using hour-angle and zenith-distance method. The procedure of the calculation of the geodetic azimuth from the astronomic azimuth was explained. The azimuth results obtained by different methods were compared and the recommendations on the minimal distance between repeat station and azimuth mark were given. The results shown in this paper were based on the observations taken on the POKU_SV repeat station.
Repeat-station surveys: implications from chaos and ergodicity of the recent geomagnetic field
Authors: Angelo De Santis  , Enkelejda Qamili  , Gianfranco Cianchini
Published: June 2021

The present geomagnetic field is chaotic and ergodic: chaotic because it can no longer be predicted beyond around 6 years; and ergodic in the sense that time averages correspond to phase-space averages. These properties have already been deduced from complex analyses of observatory time series in a reconstructed phase space and from global predicted and definitive models of differences in the time domain. These results imply that there is a strong necessity to make repeat-station magnetic surveys more frequently than every 5 years. This, in turn, will also improve the geomagnetic field secular variation models. This report provides practical examples and case studies.

 
Observing geoethics in mining and in ground-water development: An Indian experience
Authors: Shrikant Daji Limaye
Published: June 2021

Two famous quotes from ‘Mahatma Gandhi’, the Indian philosopher, are helpful in describing the foundation of geoethics: (a) “God has provided enough resources for everyone’s need but not for everyone’s greed” and (b) “Before starting a development project, first think about the effects which the project would have on the poorest of the poor people in the Society”. Geoethics is relatively a new branch in geosciences. It lies at the meeting point of geosciences, sociology and philosophy. Much earlier in the history of sciences such as nuclear physics, biology or chemistry, ethical principles attracted the attention of social leaders and philosophers while using laboratory research for field trials and applications on a large scale. Using the research not for atomic bombs but for atomic energy and not for chemical weapons but for chemical products and drugs was the priority of social leaders. In Italy, geoethics originated with philosophers and later on got the support from geologist. In other countries geoscientists working primarily in mining industry promoted geoethics for ensuring socially responsible behavior on the part of mining companies.
Aspetti diversi applicativi dell'elettrogeosmosi transitoria
Authors: A. BELLUIGI
Published: June 2021

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La crosta terrestre, dagli Appennini all'Atlantico, ricostruita sulla base dei rilievi sismici
Authors: P. CALOI
Published: June 2021

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SULLA MISURA DELL'ASSORBIMENTO IONOSFERICO
Authors: PIERO DOMINICI
Published: June 2021

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STRUTTURA DELLA CROSTA TERRESTRE IN CORRISPONDENZA DELL'ITALIA CENTRALE (Gran Sasso)
Authors: D. DI FILIPPO  , L. MARCELLI
Published: June 2021

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Un metodo obiettivo per la determinazione della subsidenza degli anticicloni dinamici
Authors: F. Di Benedetto
Published: June 2021

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Caratteristiche della crosta terrestre dalle Alpi agli Appennini
Authors: P. Caloi
Published: June 2021

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Analysis of the displacement of geodetic stations during the Emilia seismic sequence of May 2012
Authors: Alessandro Caporali  , Luca Ostini
Published: June 2021

The two events of Mw 6.11 and 5.96 [EMERGEO Working Group 2012, this volume] that took place on May 20 and 29, 2012, respectively, in the Po Plain, and the associated seismic sequence, represent the response of the brittle upper crust (hypocentral depth ca. 10 km) to the compressive stress in the outer Apennine Arc. Kinematically, the motion of the Apennines that has led to a compressional regime in the Po Plain can be represented as a counterclockwise rotation, as demonstrated by the shortening of the transalpine baselines, with a rate that decreases going west [Caporali and Martin 2000]. The compressive stress field is known from borehole breakout data [Pierdominici and Heidbach 2012] and it agrees with the principal directions of the strain rate derived from global positioning system (GPS) data. The geodetic strain rate for seismic zone 912 (Dorsale Ferrarese, according to Meletti et al. [2008]) is 92.86 ±0.04 nstrain/yr, which is a relatively high value [Caporali et al. 2011]. On a more local scale, the Mirandola fault is described in the Database of Individual Seismic Sources (DISS; http://diss.rm.ingv.it/) under the ID ITIS107 as a possible individual source, and it has a position, strike, dip, size and expected maximum magnitude [Burrato et al. 2003, Carminati et al. 2010, Scrocca et al. 2007] that are very close to the main events of the 2012 sequence. Several permanent GPS stations were in activity in the area. Using ultrarapid international Global Navigation Satellite Systems (GNSS) Service (IGS) orbits and the Bernese BSW 5.0 software [Dach et al. 2007] at our computing facility, a fast solution for the coseismic displacement was published on the May 21, 2012, and on the May 30, 2012, for the events of May 20 and 29, 2012, respectively. The largest signal was about 2 cm in the North direction at the station SGIP (San Giovanni in Persiceto), which was relatively consistent with the fault-plane solution [Devoti 2012, this volume]. In this study, we present more detailed estimates of the coseismic offsets at several other stations in the area, including a kinematic solution at 30 s temporal resolution. The coseismic displacements are inverted using the Okada [1985] model and a preliminary model of the two faults is obtained for each of the two main events, taking into account the available synthetic aperture radar (SAR) data. […]

 
Quick regional centroid moment tensor solutions for the Emilia 2012 (northern Italy) seismic sequence
Authors: Silvia Pondrelli  , Simone Salimbeni  , Paolo Perfetti  , Peter Danecek
Published: June 2021

In May 2012, a seismic sequence struck the Emilia region (northern Italy). The mainshock, of Ml 5.9, occurred on May 20, 2012, at 02:03 UTC. This was preceded by a smaller Ml 4.1 foreshock some hours before (23:13 UTC on May 19, 2012) and followed by more than 2,500 earthquakes in the magnitude range from Ml 0.7 to 5.2. In addition, on May 29, 2012, three further strong earthquakes occurred, all with magnitude Ml ≥5.2: a Ml 5.8 earthquake in the morning (07:00 UTC), followed by two events within just 5 min of each other, one at 10:55 UTC (Ml 5.3) and the second at 11:00 UTC (Ml 5.2). For all of the Ml ≥4.0 earthquakes in Italy and for all of the Ml ≥4.5 in the Mediterranean area, an automatic procedure for the computation of a regional centroid moment tensor (RCMT) is triggered by an email alert. Within 1 h of the event, a manually revised quick RCMT (QRCMT) can be published on the website if the solution is considered stable. In particular, for the Emilia seismic sequence, 13 QRCMTs were determined and for three of them, those with M >5.5, the automatically computed QRCMTs fitted the criteria for publication without manual revision. Using this seismic sequence as a test, we can then identify the magnitude threshold for automatic publication of our QRCMTs.
Evaluation of soil thermal diffusivity algorithms at two equatorial sites in West Africa
Authors: Taofeek Abiodun Otunla  , Ezekiel Oluyemi Oladiran
Published: June 2021

This study presents comparisons between six algorithms used in the calculation of apparent thermal diffusivity (Kh) of the topsoil during measurement campaigns conducted at two equatorial sites. It further investigates the effects of transient and seasonal variations in soil moisture content (theta) on the estimation of Kh. The data used comprise soil temperatures (T) measured at depths of 0.05 m and 0.10 m, and theta within the period of transition from the dry season to the wet season at Ile Ife (7.55˚ N, 4.55˚ E), and for the peak of the wet season at Ibadan (7.44˚ N, 3.90˚ E). The thermal diffusivity, Kh, was calculated from six algorithms, of: harmonic, arctangent, logarithmic, amplitude, phase, and conduction-convection. The reliability of these algorithms was tested using their values to model T at a depth of 0.10 m, where direct measurements were available. The algorithms were further evaluated with statistical indices, including the empirical probability distribution function of the differences between the measured and modeled temperatures ([delta capitalized]T). The maximum absolute values of [delta capitalized]T for the six algorithms investigated were: 0.5˚C, 0.5˚C, 0.5˚C, 1˚C, 1˚C and 1˚C, respectively. Kh showed an increasing trend as theta increased from the dry season to the peak of the wet season, with R2 = 0.70 for the harmonic algorithm. The accuracy of all of the algorithms in modeling T reduced with transient variations of theta. The harmonic, arctangent and logarithmic algorithms were the most appropriate for calculating Kh for the region of study. The empirical relation between theta and Kh and the values of Kh obtained in this study can be used to improve the accuracy of meteorological and hydrological models.
The May 2012 Emilia (Italy) earthquakes: preliminary interpretations on the seismogenic source and the origin of the coseismic ground effects
Authors: Alberto Pizzi  , Vittorio Scisciani
Published: June 2021

On May 20, 2012, a Ml 5.9 earthquake (T1) occurred in the Emilia-Romagna Region of northern Italy. This was preceded by a Ml 4.1 foreshock on May 19, 2012, and followed by several aftershocks, including two Ml 5.1 events, both on the same day. On May 29, 2012, a second strong event of Ml 5.8 (T2) hit the same region, with its epicenter ca. 12 km to the WSW of the first mainshock, T1. The epicentral area of the seismic sequence covers an alluvial lowland that is occupied by both agricultural and urbanized areas, and there were 17 casualties and about 14,000 people left homeless. […] In the present study, we provide a preliminary model of the seismogenic source(s) responsible for the two mainshocks, by comparing the seismic reflection profile interpretation with the available seismological and interferometric data. Furthermore, we show the coseismic ground effects that were observed in the epicentral area during two field survey campaigns: the first conducted after the May 20, 2012, event and the second soon after the May 29, 2012, earthquake, when several sites were revisited to observe the occurrence of newly formed or 're-activated' liquefaction features. Hence, we discuss the origin and location of the coseismic features observed in the context of the local geological–geomorphological setting and with respect to the epicentral distance. Finally, we provide our interpretation for the question: "Why did the mainshock ruptures not break the surface?" […]
Activation of the SIGRIS monitoring system for ground deformation mapping during the Emilia 2012 seismic sequence, using COSMO-SkyMed InSAR data
Authors: Stefano Salvi  , Cristiano Tolomei  , John Peter Merryman Boncori  , Giuseppe Pezzo  , Simone Atzori  , Andrea Antonioli  , Elisa Trasatti  , Roberta Giuliani  , Simona Zoffoli  , Alessandro Coletta
Published: June 2021

On May 20, 2012, at 02:03 UTC, a moderate earthquake of local magnitude, Ml 5.9 started a seismic sequence in the central Po Plain of northern Italy The mainshock occurred in an area where seismicity of comparable magnitude has neither been recorded nor reported in the historical record over the last 1,000 years. The aftershock sequence evolved rapidly near the epicenter, with diminishing magnitudes until May 29, 2012, when at 07:00 UTC a large earthquake of Ml 5.8 occurred 12 km WSW of the mainshock, starting a new seismic sequence in the western area; a total of seven earthquakes with Ml >5 occurred in the area between May 20 and June 3, 2012. Immediately after the mainshock, the Italian Department of Civil Protection requested the Italian Space Agency to activate the Constellation of Small Satellites for Mediterranean Basin Observation (COSMO-SkyMed) to provide Interferometric Synthetic Aperture Radar (InSAR) coverage of the area. COSMO-SkyMed consists of four satellites in a 16-day repeat-pass cycle, with each carrying the same SAR payload. In the current orbital configuration, within each 16-day cycle, image pairs with temporal baselines of 1, 3, 4 and 8 days can be formed from the images acquired by the four different sensors. Combined with the availability of a wide range of electronically steered antenna beams with incidence angles ranging from about 16˚ to 50˚ at near-range, this capability allows trade-offs between temporal and spatial coverage to be exploited during acquisition planning. A joint team involving the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA-CNR) was activated to generate InSAR-based scientific products to support the emergency management. In this framework, the ASI and DPC requested that INGV activated the Space-based Monitoring System for Seismic Risk Management (SIGRIS). SIGRIS consists of a hardware/software infrastructure that is designed to provide the DPC with value-added information products in the different phases of the seismic cycle. During earthquake emergencies, its goal is to rapidly provide decision-support products, such as validated ground-displacement maps and seismic source models. This study reports the details of the activation of the SIGRIS system in the case of the Emilia sequence. It provides a description of the COSMO-SkyMed datasets and processing procedures, as well as selected interferometric results for the coseismic and post-seismic ground deformation. […]
Is blind faulting truly invisible? Tectonic-controlled drainage evolution in the epicentral area of the May 2012, Emilia-Romagna earthquake sequence (northern Italy)
Authors: Pierfrancesco Burrato  , Paola Vannoli  , Umberto Fracassi  , Roberto Basili  , Gianluca Valensise
Published: June 2021

For decades, alluvial plains have been the areas of the fastest population growth over most of the globe. Modern societies demand growing extensions of flat and easily accessible land to accommodate the swelling urban areas, booming industrial districts, large power plants, and multi-runway airports. But how can we tell if such flat areas hide large active faults? How can we assign a significant pre-instrumental earthquake to its causative source? In other words, how can modern societies deal with buried, that is to say, 'invisible' faults, and with the elusiveness of the hazards they can pose? The issue of blind faulting became widely debated in the Earth sciences community in 1989, following the publication of a summary on a sequence of 'hidden earthquakes' that hit central and southern California, USA, between 1983 and 1987, and following the October 17, 1989, Loma Prieta, California, earthquake (Mw 6.9). These earthquakes shattered the accepted belief that large earthquakes are associated with large topographic contrasts; i.e., that they usually take place in mountainous terrains, and that their causative faults are expressed at the surface. Stein and Yeats [1989] spelled out clearly that "...large earthquakes can take place not only on faults that cut the Earth's surface, but also on 'blind' faults under folded terrain". Due to the growing concentrations of population and infrastructures in low topography areas, although such earthquakes might pose comparable hazards, they can come with substantially greater risk than earthquakes that occur in hilly or mountainous terrains. [...]
Earth electricity: a review of mechanisms which cause telluric currents in the lithosphere
Authors: Daniel S. Helman
Published: June 2021

Telluric currents are natural electrical phenomena in the Earth or its bodies of water. The strongest electric currents are related to lightning phenomena or space weather. Earth electricity can cause damage to structures, and may be useful for earthquake forecasting and other applications. Thirty-two distinct mechanisms that cause Earth electricity are described, and a broad selection of current research is highlighted.
Magnetic anomalies of steel drums: a review of the literature and research results of the INGV
Authors: Marco Marchetti  , Vincenzo Sapia  , Alessandro Settimi
Published: June 2021

The detection and evaluation of the status of disposal sites that contain hazardous waste materials is becoming an increasingly important element in environmental investigations. Close cooperation between the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Volcanology and Geophysics) in Rome and the Italian environmental police has resulted in numerous underground investigations of different buried materials. Among the geophysical investigation tools, magnetometry is the most effective, rapid and precise of all of the geophysical methods for localizing buried steel drums. Analysis of magnetic map anomalies can provide a variety of information about buried materials, including extension, distribution and depth, with processing of the acquired magnetic data. This information is also very useful in case of excavations that are aimed at the recovery of hazardous waste. This study determines the most relevant analyses reported in the literature, with modeling of magnetometric methods for environmental applications both theoretically and experimentally. Some studies and research results achieved by the INGV in relation to magnetic anomalies produced by buried steel drums are also reported, as found in field operations and as achieved from test sites.
Late Quaternary paleoseismic sedimentary archive from deep central Gulf of Corinth: time distribution of inferred earthquake-induced layers
Authors: Corina Campos  , Christian Beck  , Christian Crouzet  , Eduardo Carrillo  , Aurélien Van Welden  , Efthymios Tripsanas
Published: June 2021

A sedimentary archive corresponding to the last 17 cal kyr BP has been studied by means of a giant piston core retrieved on board R/V MARION-DUFRESNE in the North Central Gulf of Corinth. Based on previous methodological improvements, grain-size distribution and Magnetic Susceptibility Anisotropy (MSA) have been analysed in order to detect earthquake-induced deposits. We indentified 36 specific layers -Homogenites+Turbidites (HmTu) - intercalated within continuous hemipelagictype sediments (biogenic or bio-induced fraction and fine-grained siliciclastic fraction). The whole succession is divided into a non-marine lower half and a marine upper half. The “events” are distributed through the entire core and they are composed of two terms: a coarse-grained lower term and an upper homogeneous fine-grained term, sharply separated. Their average time recurrence interval could be estimated for the entire MD01-2477 core. The non-marine and the marine sections yielded close estimated values for event recurrence times of around 400 yrs to 500 yrs.