bluuebunny/crossref_metadata_2025 huggingface dataset:
On the modeling of strong motion parameters and correlation with historical macroseismic data: an application to the 1915 Avezzano earthquake
Authors: R. Berardi  , A. Mendez  , M. Mucciarelli  , F. Pacor  , G. Longhi  , C. Petrungaro
Published: June 2021

This article describes the results of a ground motion modeling study of the 1915 Avezzano earthquake. The goal was to test assuinptions regarding the rupture process of this earthquake by attempting to model the damage to historical monuments and populated habitats during the earthquake. The methodology used combines stochastic and deterministic modeling techniques to synthesize strong ground motion, starting from a simple characterization of the earthquake source on an extended fault plane. The stochastic component of the methodology is used to simulate high-frequency ground motion oscillations. The envelopes of these synthetic waveforms, however, are simulated in a deterministic way based on the isochron formulation for the calculation of radiated seismic energy. Synthetic acceleration time histories representative of ground motion experienced at the towns of Avezzano, Celano, Ortucchio, and Sora are then analyzed in terms of the damage to historical buildings at these sites. The article also discusses how the same methodology can be adapted to efficiently evaluate various strong motion parameters such as duration and amplitude of ground shaking, at several hundreds of surface sites and as a function of rupture process. The usefulness of such a technique is illustrated through the inodeling of intensity data from the Avezzano earthquake. One of the most interesting results is that it is possible to distinguish between different rupture scenarios for the 1915 earthquake based on the goodness of fit of theoretical intensities to observed values.
A structural analysis in seismic archaeology: the walls of Noto and the 1693 earthquake
Authors: E. Guidoboni  , P. Riva  , V. Petrini  , A. Madini Moretti  , G. Lombardini
Published: June 2021

A crucial problenl for seismic archeology is how to recognize seismic effects and how to date them. On an experimental basis. we proposed that the problem be reversed, and that we begin at the other end: i.e. by analyzing already known seismic effects on ancient structures, testified by written sources. to be able to .calibrate>> the types or possible observations and any subsequent elaborations. The choice of the walls of Noto was suggested by the fact that Noto was abandoned following the earthquake of l693 (I,= XI MCS. Me 7.5) which had already been studied in depth as part of an ING research programme (1988-92). Moreover, just after recent research, this event proved to be reconstructed with a high quality standard. Photogrammetric measurements were made on several parts of the town walls to plot a numerical model aimed at ascertaining specific aspects of the earthquake damage. An estimate of the ground acceleration during the earthquake has been attempted via non-linear finite-element analyses of a building located by the main city gate. The analyses show that. in order to obtain the building vault collapse, a ground acceleration of 0.5 to 0.7 g had to be reached during the earthquake. This result, typical of a strong earthquake such as the one of 1693, proves that an approach based on finite element analysis and a sound engineering judgment Inay be systematically applied to historical earthquake sites to obtain some estimates of ground acceleration in historical earthquakes. On the whole, this work aimed at starting up the second development phase of the great event of 1693 of which the macroseismic erfects are known. In the meantime, some possibilities of tackling structural analyses in seismic archaeology are being explored.
Effect of coast on magnetotelluric measurements in India
Authors: U. K. Singh  , Y. Kant  , R. P. Singh
Published: June 2021

Magnetotelluric soundings were carried out at 45 stations along a north-south profile near western coast of India. The magnetotelluric results in the E- and H-polarizatjons showed a significant difference in behaviour. Detailed two-dimensional modelling was carried out to study the effect of the western and eastern coasts of India on magnetotelluric measurements. The effect of the coast on magnetotelluric measurements was seen near the coa"t in both the polarizations. This effect was maximum in the vicinity of the coast in broad frequency range. It is suggested that magnetotelluric measurements in the coastal region of India should be carried out in the E-polarization for a reliable vertical resistivity profile.
The intraplate Euphrates fault system-Palmyrides mountain belt junction and relationship to Arabian plate boundary tectonics
Authors: D. Alsdorf  , M. Barazaugi  , R. Litak  , D. Seber  , T. Sawaf  , D. AI-Saad
Published: June 2021

We interpret seismic data and well logs to indicate that the Euphrates graben, intersecting orthogonally with the Palmyride mountains, is an intraplate transtensional feature that probably developed in response to plate boundary stress created by a latest Cretaceous convergence event along the present-day northern boundary of the Arabian plate. The principal stress direction is proposed to lie generally parallel to the graben; hence, it may have formed as a tear in the Arabian crust while, as previously documented, the Palmyride region under- went shortening and uplift. Arabian plate boundary tectonism as well as shorteningin the Palmyrides were pe- riodically active during the entire Cenozoic, especially in Neogene and Quaternary time. However, the normal fault motions that formed the Euphrates graben were not active within the study area after the end of the Cre- taceous, and were most active during the Campanian-Maastl.ichtian. A broad, Cenozoic depression overlying the Euphrates graben and most of Eastern Syria is possibly related to the Mesopotamian foredeep that devel- oped in response to the nearby Zagros continental collision zone during Neogene and Quaternary time. Cenozoic strike-slip faults lie between the Euphrates graben and the Palmyrides belt and may kinematically separate the Palmyrides from the Euphrates system.
Another way of deriving the ring current decay time during disturbed periods
Authors: M. M. Zossi de Artigas  , J. R. Manzano
Published: June 2021

Coupling parameter, E, and the total energy dissipated by the magnetosphere, UT, are determined for six disturbed periods, following three known criteria for UT computation. It is observed that UT exceeds E for Dst < -90 nT, for alI models. Differences between models reside on the estimated valnes for the particles' life time il1 the equatorial ring current. The values of TR, used in the models, are small during the main phase of the di."turbance, in disagreement with the charge exchange life time of the majority species, H+ and O'-. Based on this conclusion, a different criterion to calculate TR is proposed, differentiating the different stages of the perturbation. TR is calculated, for the main phase of the storm, from the rate of energy deposition estimation, Q, in the ring current. For Dst recovery phase, the vallles are obtained from a ring current decay law computation. The UTvu calculated, physically more coherent with the processes occurring during the event, is now smaller than expected. In this sense, it is understood that the power generated by the solar wind-magnetosphere dy- namo, should also be distributed in the inner magnetosphere, auroral zones and equatorial ring current, as in the outer magnetosphere, plasmoids in the tail shot in antisolar direction. A further adjustment of E, with the Chapman-Ferraro distance, 10' variable, has been made. Although the reslllts, improve the estimation of E, they are sti!l smaller than UT, except UTNU, for some disturbed periods. This result indicates the uncertainty in the computation of the input energy, by using the many expressions proposed in the literature, which are always presented as laws proportional to a given group of parameters, with an unknown factor of proportionality, which deserves more detailed physical analysis.
Assessment of potential strong ground motions in the city of Rome
Authors: A. Rovelli  , A. Caserta  , L. Malagnini  , F. Marra
Published: June 2021

A methodology is used which combines stochastic generation of random series with a finite-difference technique to estimate the expected horizontal ground motion for the city of Rome as induced by a large earthquake in the Central Apennines. In this approach, source properties and long-path propagation are modelled through observed spectra of ground motion in the region, while the effects of the near-surface geology in the city are simulated by means of a finite-difference technique applied to 2-D models including elastic and anelastic properties of geologic materials and topographic variations. The parameters commonly used for earthquake engineering purposes are estimated from the simulated time histories of horizontal ground motion. We focus our attention on peak ground acceleration and velocity, and on the integral of the squared acceleration and velocity (that are proportional to the Arias intensity and seismic energy flux, respectively). Response spectra are analyzed as well. Parameter variations along 2-D profiles visualize the effects of the small-scale geological heterogeneities and topography irregularities on ground motion in the case of a strong earthquake. Interestingly, the largest amplification of peak ground acceleration and Arias intensity does not necessarily occur at the same sites where peak ground velocity and flux of seismic energy reach their highest values, depending on the frequency band of amplification. A magnitude 7 earthquake at a distance of 100 km results in peak ground accelerations ranging from 30 to 70 gals while peak ground velocities are estimated to vary from 5 to 7 cm/s; moreover, simulated time histories of horizontal ground motion yield amplitudes of 5% damped pseudovelocity response spectra as large as 15-20 cm/s for frequencies from 1to 3 Hz. In this frequency band, the mean value is 7 cm/s for firm sites and ranges from 10 to 13 cm/s for soil sites. All these results are in good agreement with predictions based on regressions of Italian and Western North American data.
Realistic modelling of observed seismic motion in compIex sedimentary basins
Authors: D. Fah  , G. F. Panza
Published: June 2021

Three applications of a numerical technique are illustrated to model realistically the seismic ground motion for complex two-dimensional structures. First we consider a sedimentary basin in the Friuli region, and we model strong motion records from an aftershock of the 1976 earthquake. Then we simulate the ground motion caused in Rome by the 1915, Fucino (Italy) earthquake, and we compare our modelling with the damage distribution observed in the town. Finally we deal with the interpretation of ground motion recorded in Mexico City, as a consequence of earthquakes in the Mexican subduction zone. The synthetic signals explain the major characteristics (relative amplitudes, spectral amplification, frequency content) of the considered seismograms, and the space distribution of the available macroseismic data. For the sedimentary basin in the Friuli area, parametric studies demonstrate the relevant sensitivity of the computed ground motion to small changes in the subsurface topography of the sedimentary basin, and in the velocity and quality factor of the sediments. The relative Arias Intensity, determined from our numerical simulation in Rome, is in very good agreoment with the distribution of damage observed during the Fucino earthquake. For epicentral distances in the range 50 km-100 km, the source location and not only the local soil conditions control the local effects. For Mexico City, the observed ground motion can be explained as resonance effects and as excitation of local surface waves, and the theoretical and the observed maximum spectral amplifications are very similar. In general, our numerical simulations estimate the maximum and average spectral amplification for specific sites, i.e. they are a very powerful tool for accurate micro-zonation
Source mechanisms and near-source wave propagation from broadband seismograms
Authors: J. Virieux  , A. Deschamps  , J. Perrot  , J. Campos
Published: June 2021

Recording seismic events at teleseismic distances with broadband and high dynamic range instruments provides new high-quality data that allow us to interpret in more detail the complexity of seismic rupture as well as the heterogeneous structure of the medium surrounding the source where waves are initially propagating. Wave propagation analysis is performed by ray tracing in a local cartesian coordinate system near the source and in a global spherical coordinate system when waves enter the mantle. Seismograms are constructed at each station for a propagation in a 2.5-D medium. Many phases can be included and separately analyzed; this is one of the major advantages of ray tracing compared to other wave propagation techniques. We have studied four earthquakes, the 1988 Spitak Armenia Earthquake (Ms = 6.9), the 1990 Iran earthquake (Ms = 7.7), the 1990 romanian earthquake (Ms = 5.8) and the 1992 Erzincan, Turkey earthquake (Ms = 6.8). These earthquakes exhibit in different ways the complexity of the rupture and the signature of the medium surrounding the source. The use of velocity seismograms, the time derivative of displacement, increases the difficulty of the fit between synthetic seismograms and real seismograms but provides clear evidence for a need of careful time delay estimations of the different converted phases. We find that understanding of the seismic rupture as well as the influence of the medium surrounding the source for teleseismically recorded earthquakes requires a multi-stop procedure: starting with ground displacement seismograms, one is able to give a first description of the rupture as well as of the first-order influence of the medium. Then, considering the ground velocity seismograms makes the fit more difficult to obtain but increases our sensitivity to the rupture process and early converted phases. With increasing number of worldwide broadband stations, a complex rupture description is possible independently of field observations, which can be used to check the adequacy of such complicated models.
Teleseismic analysis of the 1990 and 1991 earthquakes near Potenza
Authors: G. Ekstrom
Published: June 2021

Analysis of the available teleseismic data for two moderate earthquakes near the town of Potenza in the Southern Apennines shows that both involve strike-slip faulting on a plane oriented approximately east-west. Only the larger, 5 May 1990, earthquake is sufficiently large for analysis by conventional teleseismic waveform inversion methods, and is seen to consist of a foreshock followed 11 seconds later by the main release of moment. The focal mechanism and seismic moment of the 26 May 1991 earthquake is determined by quantitative comparison of its 15-60 s period surface waves with those generated by the 5 May 1990 event. The focal mechanisms for the two events are found to be very similar. The 1991 earthquake has a scalar moment that is approximately 18% that of the 1990 mainshock. Comparison of higher frequency P waves for the two events, recorded at regional distance, shows that the ratio of trace amplitudes is smaller than the ratio of scalar moments, suggesting that the stress drop for the 1991 event is distinctly smaller than for the 1990 mainshock.
Broad-band moment tensor inversion from single station, regional surface waves for the 1990, NW-Iran earthquake sequence
Authors: D. Giardini  , L. Malagnini  , B. Palombo  , E. Boschi
Published: June 2021

e present a method for the inversion of complete waveforms in the 5-30 mHz frequency band for moment tensor determination. The method is based on the calibration of phase and group velocity dispersion curves for Rayleigh and Love fundamental modes to account for heterogeneous lithospheric structure, and is applied to the analysis of single station records of the VSL MEDNET station for the 1990 NW Iran earthquake sequence (the events of June 20, 21 and 24). The revised seismic moment of the June 20, 1990 Iranian earthquake is Mo = 1.56 x 1027 dyne-cm, corresponding to Mw = 7.4. The method proves to be a very robust tool for the analysis of moderate and large earthquakes at regional distances, producing consistent moment tensor solutions trom single station inversions in narrow (2-4 mHz) and wide (up to 20 mHz) frequency bands across the whole band of interest.
Current knowledge on the crustal properties of Italy
Authors: C. Morelli
Published: June 2021

The recent advances in experimental petrography together with the information derived from the super-deep drilling projects have provided additional constraints for the interpretation of refraction and reflection seismic data. These constraints can also be used in the interpretation of magnetic and gravity data to resolve nonuniqueness. In this study, we re-interpret the magnetic and gravity data of the Italian peninsula and neighbouring areas. In view of the constraints mentioned above, it is now possible to find an agreement between the seismic and gravity models of the Central Alps. By taking into account the overall crustal thickness, we have recognized the existence of three types of Moho: 1) European which extends to the north and west of the peninsula and in the Corsican-Sardinian block. Its margin was the foreland in the Alpine Orogeny and it was the ramp on which European and Adriatic mantle and crustal slices were overthrusted. This additional load caused bending and deepening and the Moho which now lies beneath the Adriatic plate reaching a maximum depth of approximately 75 km. 2) Adriatic (or African) which lies beneath the Po plain, the Apennines and the Adriatic Sea. The average depth of the Moho is about 30-35 km below the Po plain and the Adriatic Sea and it increases toward the Alps and the Tyrrhenian Sea (acting as foreland along this margin). The maximum depth (50 km) is reached in Calabria. 3) Pery-Tyrrhenian. This is an oceanic or thinned continental crust type of Moho. It borders the oceanic Moho of the Tyrrhenian Sea and it acquires a transitional character in the Ligurian and Provençal basins (<15 km thickness) while further thickening occurs toward the East where the Adriatic plate is overthrusted. In addition, the interpretation of the heat flow data appears to confirm the origin of this Moho and its geodynamic allocation.
Statistical study of epicentre alignment in the broader Aegean area
Authors: P. Tosi  , V. De Rubeis  , E. Papadirnitriou  , P. Dimitriu
Published: June 2021

Accurate data concerning shallow (h = 60 km) earthquakes (Ms =4.5) that occurred in the broader Aegean area are used to point out the presence of linear seismogenic structures (seismolineaments). The earthquake data were analyzed by the use of a specific algorithm, and the directions of the best alignment of epicentres were found. The algorithm is based on statistical criteria applied within a circular area with the aim of searching for the best direction of alignment; this is then tested, to discriminate whether or not the pattern could stem from a random distribution of epicentres, or whether it is effectively the result of a linear seismic structure; the procedure is repeated to cover the whole area examined. The resulting lineaments can be regarded as individual tectonic units, as they usually coincide with known active faults or fault systems. An interpretation is given of the spatio-temporal evolution of the seismicity along the lineaments in terms of the asperity model.
The Australian National Seismograph Network
Authors: D. Jepsen
Published: June 2021

The Australian Seismological Centre of the Australian Geological Survey Organisation, operates and co-operates a national seismograph network consisting of 24 analogue and 8 digitally telemetred (3 broadband) stations (see fig. 1 and table 1). The network covers the Australian continent and the Australian Antarctic Territory.
The IRIS Global Seismographic Network
Authors: R. Butler
Published: June 2021

Since the last FDSN meeting in December 1992, the IRIS Global Seismographic Network (GSN) has made significant progress toward meeting its goals of a uniform, globally distributed, network of broadband seismographic stations. More GSN stations were installed or upgraded than in any previous year. A total of 15 new stations entered into operation, bringing the total number of stations in the GSN to 54. Additionally, 4 existing GSN stations were upgraded with 24-bit data acquisition systems.
The capability of three component substation FIA1 at local and regional distances. Comparisons with FINESA and Helsinki bulletins
Authors: M. Tarvainen
Published: June 2021

The automatic analysing capability of the three component substation called hereafter also FIA1 (coordinates: 61.4444°N, 26.0793°E) is studied. The detections and daily bulletins of FINESA (renamed as FINESS since August 1993) are used as a basis of the study. At the three component substation FIA1 a detector bulletin producer of type Husebye Ruudwas used to detect events and after forming a single station daily bulletin the common detections with FINESA were taken into a more detailed examination. From 689 detections of FINESA (also referred to as FIAO) the three component substation could associate 258 events. The main part of events were mining and quarry explosions in Estonia, Russia, north of St. Petersburg and Finland, at distances up to 250 km. The diurnal distribution of events was studied and the connections to certain mines were attempted to be determined. It is found that certain mining areas have very specified shooting times, thus making it possible to monitor this kind of areas under predefined procedure. The median difference of azimuths obtained from the three component station compared with FINESA azimuths was 50 and the median difference of distance was as small as 6.2 km. In these comparisons the siting of the three component sensor was not taken into account, even though it is not located in the centre of the array. The main sources of location differences are found to be the errors of azimuth and veiled later phases. Sometimes the phase pickings of the two different methods did not give any coinciding results, even though the P detections occurred simultaneously. Also, the deviation of azimuths under poor SNR circumstances caused clear location biases. To investigate the detection and locating performance of the three component sub station FIA1 at local and regional distances, the results were compared with the preliminary weekly analysis and Helsinki bulletins of the Finnish National Data Centre (FNDC), which handled 480 events during the test period. Altogether 205 events located by FIA1 could easily be connected with the results of the Finnish National Data Centre. The median errors in azimuth and distance of these connected events were quite small, 8.9° and 9.1 lan, respectively.
On site inspection for nuclear test ban verirication
Authors: P. D. Marschall
Published: June 2021

The problem of verifying compliance with a nuclear test ban treaty is mainly a technical one. However the problem of detecting, locating and identifying nuclear explosions has, since the late 1950s, been intimately involved with the political problems associated with negotiating a treaty. In fact there are few other areas in which policy, diplomacy and science have been so interwoven. This paper attempts to illustrate how technology can. be applied to solve some of the political problems which arise when considering the role of an On Site Inspection (OSI) to determine whether or not a nuclear explosion, in violation of a treaty, has occurred or not. It is hoped that the reader, with a scientific background, but with little or no experience of treaty negotiations, will gain an. insight as to how technical matters can interact with political requirements. The demands made on scientists to provide technical support for negotiating and rnonitoring compliance of a treaty have increased significanfly over the last 40 years. This is a period in which a number of major treaties have contained a significant technical component e.g. the Limited Test Ban Treaty (Threshold Treaty) and the Chemical Weapon Convention. This paper gives an indication of some of the political decisions which will have to be made and suggests some of the technical methods which are of value in the identification of a clandestine nuclear explosion.
Magnetic investigations for studying planetary interiors
Authors: M. Chiappini  , A. De Santis
Published: June 2021

Most of the magnetic methods used for investigating planetary interiors are based on the reasonable hypothesis that the mechanism for the origin of the field is an Earth-like hydromagnetic dynamo: in this case the planet has an electrically conducting fluid shell within it as in the case of the Earth's core. The present paper describes several techniques of planetary magnetic investigation which give important clues on the internal constitution of planets. Some considerations on the possible mechanisms for maintaining a dynamo and simple concepts with the help of a few non-dimensional numbers are also introduced and discussed. Then some fundamental relationships are given in order to relate the planetary magnetism to other physical parameters, such as angular rotation, core dimensions etc. It finally summarizes some results available for the planets of the Solar System.
Morphotectonics of the Mascarene Islands
Authors: R. Hantke  , A. E. Scheidegger
Published: June 2021

A study is made of the orientations (strikes/trends) of joints, valleys, ridges and lineaments, i.e. of the (potentially) morphotectonic features, of the Mascarene Islands (Reunion, Mauritius and Rodrigues) in the Indian Ocean. It turns out that a connection exists between these features on all islands. For the joints alone, the results for Mauritius as a whole agree closely with those for Rodrigues as a whole, and also partially with those of Reunion. Inasmuch as the trends of the valleys, ridges and lineaments are related to the trends (strikes) of the joints, a common morphotectonic predesign seems to be present for all features studied. The morphotectonic orientations on the island also agree closely with the trends of fracture zones, ridges and trenches in the nearby ocean bottom; which has had a bearing on the theories of the origin of the Mascarene Islands. Generally, a hot-spot origin is preferred for Reunion, and may be for Mauritius as well, although differing opinions have also been voiced. The dynamics of a hot-spot is hard to reconcile with the close fit of the joint strikes in Réunion with the trends of the Madagascar and Rodrigues fracture zones. The closely agreeing joint maxima in Mauritius and Rodrigues í across the deep Mauritius trench í also agree with the trend of that trench and with the trend of the Rodrigues fracture zone. Thus, it would appear as most likely that the trends of joints and of fracture zones are all part of the same pattern and are due to the same cause: viz. to action of the neotectonic stress field.
Displacement field of the Italian area from permanent GPS stations
Authors: F. Riguzzi  , A. Zanutta
Published: June 2021

A network of nine permanent GPS stations, six of them located in Italy (Cagliari, Matera, Medicina, Noto, Padova and Torino), the other three in Central Europe (Graz, Zimmervald and Wettzell) was been analyzed four times from October 1996 till 1998. After the GPS data processing, a rigorous statistical analysis based on the F (Fisher) test applied on the detected coordinate differences showed significant displacement at Matera, Medicina and Noto. The mean velocities computed for these sites with respect to Wettzell are (0.6 ± 0.3) cm/yr for Matera, (0.7 ± 2) cm/yr for Medicina and (0.6 ± 0.3) cm/yr for Noto.GPS velocities agree with those derived by VLBI and ITRF96 solutions, provided error ellipses are taken into account. The deformation analysis of the last time span shows a suspicious horizontal jump at Padova of (1.0 ± 0.1) cm corresponding to an antenna changing within the same period. This fact shows, in spite of the care used in permanent GPS installation, how the results of the deformation analysis may be strongly conditioned by site problems.
The intrusive complexof the Island of Giglio: geomagnetic characteristics of plutonic facies with low susceptibility contrast
Authors: O. Faggioni  , D. Westerman  , F. Innocenti  , N. Beverini  , C. Carmisciano  , R. Cavallini  , A. Dini
Published: June 2021

Two main plutonic facies characterize the intrusive complex of the Island of Giglio, and the trend of their contact at depth has been modelled using a 2D½ analysis based on a detailed geomagnetic survey in order to verify the geological hypothesis of the subsurface geometry of this contact. The magnetic anomaly connected with the discontinuity is quite low, due to the small difference between the magnetic susceptibilities of the two granitic facies. Development of this model of inversion of the magnetic field, which is in good agreement with the geological interpretation, was made possible by: 1) accurate control of the geomagnetic time variations and consequent temporal reduction, 2) a very low level of the artificial magnetic noise, 3) high density of the magnetic survey, 4) detailed knowledge of the mapped geologic contact between facies and of their petrologic characteristics, and 5) direct local measurements of the magnetic susceptibilities of the key lithologies. The model shows the trends of the geological contact, as projected in three E-W sections, that dips eastward in the range between 210 and 540, supporting the geologic hypothesis that the Pietrabona facies represents an external shell of the shallowly emplaced Giglio monzogranite intrusion.
Examples of ac resistivity prospecting in archaeological research
Authors: P. Mauriello  , D. Monna  , I. Bruner
Published: June 2021

In this paper we present the results of an alternating current resistivity survey, with a view to future tomographic processing. Two examples are given to evaluate the validity and the resolution of the method. The first in the Sabine Necropolis of Colle del Forno (Montelibretti, Rome), the second in the Etruscan settlement of Poggio Colla (Vicchio, Florence). All the measurements were carried out utilising current up to 512 Hz and a mobile dipole MN along straight lines, having two fixed current probes A and B. It was found that skin effect is uninfluential in the frequency range adopted. Given the absence of natural or artificial disturbances in the signal (e.g. electrode polarization and self potential), it was possible to perform very fast measurements with two operators only. Moreover, the use of a multiple dipole source configuration allows the calculation of the determinant of the apparent resistivity tensor. In the examples shown, this parameter detects the actual position of buried structures independently of the direction of the electric sources.
Potential field continuation: a comparative analysis of three different types of software
Authors: M. Ciminale  , M. Loddo
Published: June 2021

DARING.F is a new Fortran77 computer program which has been developed to perform the continuation of potential field data between arbitrary surfaces. The implemented equivalent source algorithm inverts a system of linear equations by using sparse matrix. A comparative analysis between the performance of this software and that of two computer programs (named UPWARD.F and UPNEW.F) previously written by the same authors is carried out. As a result of this analysis, some useful and important suggestions on how to obtain the highest level of accuracy of transformed data in various situations (i.e. large matrices of data, close surfaces) are given.
An experimental aeromagnetic survey in the Volturno valley area (South-Eastern Latium)
Authors: M. Chiappini  , F. Ferraccioli  , V. Bosi  , E. Bozzo  , G. Caneva  , R. Funiciello
Published: June 2021

A helicopter-borne experimental aeromagnetic survey, covering an area of 200 km2, was performed in the Volturno valley area north of the Roccamonfina volcano and south of Venafro in November 1994. Although severe logistical, instrumental and meteorological conditions significantly reduced the planned coverage, the processed magnetic image still shows a remarkable improvement in the description of the geological and structural features of the area in comparison with previous regional aeromagnetic data. A multi-directional shaded relief anomaly map displays two moderately positive NW magnetic bands associated with lavas, pyroclastics and dykes of the Roccamonfina volcanic district together with N-S, NNE-SSW and NE-SW lineations. A comparative magnetic-geologic map allows correlation with known Pleistocene faults and reveals the existence, especially in the area between Sesto Campano and Presenzano, of a larger presence of high susceptibility dykes than seen in the outcrop, which is dominated by non-magnetic carbonatic rocks. We interpret the curvilinear and intricate pattern of magnetic lineaments as suggestive of an extensional setting along the main NW structures with previous strike slip components and of tectonic activity along a N-S fabric; the latter has no superficial evidence and has also been used for magma upwelling. Overall, this local scale investigation shows both the utility and the need for further efforts in high resolution aeromagnetics in Italy both for geological and environmental purposes similar to those successfully carried out in many other countries throughout the world.
The effects of zoning methods on forecasting of the next earthquake occurrences, according to semi-Markov models
Authors: Ramin Sadeghian
Published: June 2021

Earthquakes are natural phenomena that can be viewed in three dimensions: time, space and magnitude. Earthquakes can be investigated not only physically, but also mathematically. In this study, semi-Markov models are applied, which can be considered as useful methods to analyze and forecast the occurrence of future earthquakes based on previous earthquake data. In the present study, the target region, Iran, is divided into zones, and each zone is examined as one of the semi-Markov model states. Several methods to determine the levels of forecasting error are then introduced and applied to the target area. The results of the application of these semi-Markov models to investigate and forecast the occurrence of future earthquakes are obtained and analyzed mathematically. A new zoning method is developed and compared with that of Karakaisis, through the proposed forecasting method. Moreover, the effects of the type of zoning and the number of zones on the forecasting error of the next earthquake occurrences are investigated using several algorithms.
Studio luacrosismico del terremoto di Reggio Calabria del 16 Gennaio 1975
Authors: A BOTTARI  , E. Lo GIUDICE
Published: June 2021

The results of a macroseismic investigation carried out in 362 inhabited centres of the provincies of Reggio Calabria, Messina, Catania, and Catanzaro are presented in relation to the Reggio earthquake of 16 January 1975. The importance and the location of damage, as well as
Some seismologieal results and geostructural suggestions from a study of the Reggio Calabria earthquake of 16 January, 1975
Authors: A BOTTARI  , F. BROCCIO  , E. L o GIUDICE
Published: June 2021

Starting from the analytic determination of the most important parameters of the Reggio Calabria earthquake, several geostructural hypotheses are analyzed and discussed. The statistical hvpocentre, calculated in two separate phases for (lie epicentral coordinates (q> = 38°04'28"; A = 15°38'55") and for the depth (h = 10.04 km), is consistent with an earlier macroseismic estimation. The travel times for the first arrivals, limited to the distance interval 0 ^ ¿1° ^ 12 can be approximated by means of the three linear equations: which can be interpreted as the travel-time curves of the direct (Pg) and refracted (Pn i , P„2) longitudinal waves. The existence of a focal mechanism, compatible with a couple + oppositely directed force model is deduced from a study of the signs of the first impulses. This model includes faulting and displacement with dislocation plane N 22"K and inclination of ~ 75° towards XI 12°E. Considering the focal location and our geostructural knowledge of the area involved, the Reggio Calabria earthquake can be explained by a process of tectonic distension due to the drift of the Calabrian Arc and to other reliable geostructural elements. The explanation is critically evaluated in relation to the tectonic forces involving the Strait of Messina and the volcanic zone of Etna.
The estimation of seismic risk for central Italy
Authors: M. CAPUTO  , V. I. KEILIS-BOROK  , T. I. KRONROD  , G. M. MOLCHAN  , G. F. PANZA  , A. PIVA  , V. M. PODGAETSKAJA  , D. POSTPISCHI
Published: June 2021

The estimation of seismic risk is made for three types of objects in the central Italy, considering three kinds of models: 1) - A(2I,g): the intensity of the Poisson's flow of earthquakes, M being the magnitude, g the liypocentre. 2) - I(g,g,M): giving the distribution on the surface for a single earthquake (g,M), g being the epicentre. 3) - x(g,I): giving the effect x of the shakings of intensity / , g being the position of the object. For actual decision-making additional computations may be necessary in order to estimate how our results are influenced by the errors in these models. However practical decision can be made on the basis of these data, because the experience shows that normally results are exagerated.
A teleseismic finite-fault rupture model for the August 17, 1999, İzmit earthquake (Mw = 7.6): implications for the seismic nucleation phase
Authors: Murat Utkucu  , Hatice Durmuş
Published: June 2021

A linear finite-fault inversion procedure is applied to teleseismically recorded broadband P and SH velocity waveforms of the August 17, 1999, İzmit earthquake, to derive spatial and temporal distributions of the co-seismic slip over the representative three-segment model fault. The model fault is longer than the mapped surface rupture, and it extends offshore for 25 km in the west, to define the western end of the earthquake rupture. The teleseismically derived slip model suggests a bilateral rupture with a total seismic moment release of 2.6 ×1020 Nm, and that the rupture was dominated by failure of two major asperities with peak slip amplitudes reaching 7 m. The hypocentral area was represented by the relatively low displacement that separated the large asperities. In the west, the rupture reached the eastern entrance of the Çınarcık basin beneath the Sea of Marmara, with an average slip of ca. 2 m. This indicates that the rupture propagated offshore for ca. 20 km after crossing Hersek Peninsula. The analysis also reveals that the total rupture process time was 32 s, while the main seismic moment release, which corresponded to the rupture of the two large asperities, occurred between 4 s and 16 s after rupture initiation. The strong wave energy arrivals from the failure of the large asperities were preceded by weak wave arrivals in the initial section of the teleseismic waveforms used in this study. Along with some observations from previous studies, this emergent onset of the wave arrivals prompts us to discuss the possibility of a seismic nucleation process for this earthquake.
Sistemi di propulsione elettrotermica
Authors: R. MONTI
Published: June 2021

Si pongono ill risalto le liniitazioni della propulsione
chimica rispetto a quella terinica non eonvenzionale e si esaniinano i problemi
e le applicazioni dei sistemi elettrotermiei. Si illustrano alcune proposte per
migliorare il processo di riassociazione aH'interno deH'ugello in presenza di
fenomeni di non-equilibrio chimico.
ALCUNI RISULTATI DI UNA RICERCA SULLA DENSITA DEI CORPI METEORICI
Authors: F. VERNIANI
Published: June 2021

Dopo una breve discussione delle cause dell'incertezza
attualmente esistente al riguardo della densita e della struttura dei corpi
meteorici, viene presentato un inetodo per calcolare la densita delle meteore
utilizzando dati fotograflci. Inflne vengono esposti i risultati ottenuti dall'autore
analizzando dati pubblicati ad Harvard. Tali risultati mostrano
chiaramente clie quasi t u t t e le meteore hanno una densita minore di 1 g cm-3
e quindi una struttura porosa in accordo con il modello cometario di Whipple.
Hungarian repeat station survey, 2010
Authors: Péter Kovács  , András Csontos  , Balázs Heilig  , András Koppán
Published: June 2021

The last Hungarian repeat station survey was completed between October 2010 and February 2011. Declination, inclination and the total field were observed using one-axial DMI fluxgate magnetometer mounted on Zeiss20A theodolite and GSM 19 Overhauser magnetometer. The magnetic elements of the sites were reduced to the epoch of 2010.5 on the basis of the continuous recordings of Tihany Geophysical Observatory. In stations located far from the reference observatory, the observations were carried out in the morning and afternoon in order to decrease the effect of the distant temporal correction. To further increase the accuracy, on-site dIdD variometer has also been installed near the Aggtelek station, in the Baradla cave, during the survey of the easternmost sites. The paper presents the technical details and the results of our last campaign. The improvement of the accuracy of the temporal reduction by the use of the local variometer is also reported.
Modalità di immissione elettrica di liquidi nel suolo (EGE integrale)
Authors: A. Belluigi
Published: June 2021

Si da la teoria dell'elettrogetto EGE integrale EGEI,un liquido, isobaricamente immesso tramite anodo in un mezzo poroso, esua rimozione (più o meno parziale, ritmica o no), al catodo.Caratterizzano quest'effetto elettrogeocinetico: pressioni idrogeostatica,catodica, portate anodica e catodica, liquidi immessi, estratti, ritenuti nelterreno.Con elettrotrattamento a tensione (c.c.) costante, rapidi emungimenti,sufficientemente distanziati nel tempo, le precedenti grandezze, semplificate,constano di più addendi, i primi dei quali coincidenti con quelli già riconosciutiper l'EGE parziale (senza prelievi fluidi), altri apporti specifici dell'EGEintegrale (con prelievi fluidi).L'assorbimento anodico appare dapprima quasi insensibile al pompaggio,aumenta, tocca un massimo, torna a diminuire più dolcemente neltempo.L'effetto estrattivo si fa risentire, con incremento iniettivo massimosfasato in ritardo, per poi estinguersi.Isoprelievi catodici, intervallati con tempi adeguati (frequenza ottima),correlativi ad adduzioni anodiche, comporteranno « contenimenti fluidi massimi», notevolmente maggiori che per intervalli diversi.Così operando, pur sostando al « monoprelievo », si realizza un « invasamentodi liquido » massimo possibile, in tempo relativamente breve.
LE SESSE DEL LAGO DI GARDA. Parte IV. OSCILLAZIONI LIBERE DEL BACINO ORIENTALE
Authors: P. CALOI  , M. C. SPADEA
Published: June 2021

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L'ATTUALE DEFORMAZIONE DELLA CROSTA TERRESTRE
Authors: SILVIO POLLI
Published: June 2021

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Note sopra un breve periodo sismico svoltosi nel territorio di Montespertoli durante il mese di giugno 1958
Authors: M. DE PANFILIS
Published: June 2021

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SULLE OSCILLAZIONI LIBERE DEL LAGO DI CALDONAZZO
Authors: P. CALOI  , M. C. SPADEA
Published: June 2021

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SUL GRADIENTE ADIABATICO DI TEMPERATURA NELL'INTERNO DELLA TERRA
Authors: PAOLO EMILIO VALLE
Published: June 2021

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SULLA CURVATURA E TORSIONE DEL CAMPO DI GRAVITA'
Authors: ANTONIO MARUSSI
Published: June 2021

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DROMOCRONE PER TERREMOTI VICINI E VELOCITA' DELLE ONDE NELL'ITALIA CENTRALE
Authors: D. DI FILIPPO  , L. MARCELLI
Published: June 2021

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LA SPEDIZIONE DELL'I.N.G. A KHARTOUM IN OCCASIONE DELL'ECLISSE TOTALE DI SOLE DEL 25/2/1952
Authors: R. ClALDEA
Published: June 2021

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PERFEZIONAMENTI APPORTATI AD UN APPARATO FAC-SIMILE
Authors: MARCO FRANK
Published: June 2021

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NORME E RISULTATI NELL'USO DEL COMPENSATORE A CORRENTE ALTERNATA «BICARAM»
Authors: A. BELLUIGI
Published: June 2021

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L'OSSERVATORIO GEOFISICO INSTALLATO A KHARTOUM IN OCCASIONE DELL'ECLISSE DI SOLE DEL 25-2-1952
Authors: R ClALDEA  , P. DOMINICI
Published: June 2021

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STUDIO DELLA RADIOATTIVITA' DELLE LAVE DELL'ETNA COL METODO DELLE EMULSIONI NUCLEARI
Authors: L. BARBERA  , M. CURATOLO  , M. M. INDOVINA ADDARIO  , M. SANTANGELO
Published: June 2021

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Coefficienti di portata delle stazioni radio
Authors: S. Silleni
Published: June 2021

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Sulla dispersione delle onde sismiche nell'ambito delle altissime frequenze
Authors: P. Caloi
Published: June 2021

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Sulla teoria delle maree atmosferiche gravitazionali
Authors: F. Mariani
Published: June 2021

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La natura fisica dell'ipocentro del terremoto profondissimo nell'Argentina settentrionale (14 agosto 1950)
Authors: D. Di Filippo  , L. Marcelli
Published: June 2021

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DETERMINAZIONI DELLE COSTANTI ARMONICHE E NON ARMONICHE DELLE MAREE PER I PORTI DI BELVEDERE, CORTELLAZZO, FARO ROCCHETTA E CHIOGGIA
Authors: SILVIO POLLI
Published: June 2021

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PERIODICITA' DENDROLOGICHE E CICLI SOLARI
Authors: FRANCESCO VERCELLI
Published: June 2021

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IL BATISISMO DEL 28 AGOSTO 1946 E LA PRONDITA' DEL NUCLEO TERRESTRE
Authors: P. CALOI  , F. PERONACCI
Published: June 2021

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SULLA NATURA DELLE CAUSE CHE GENERANO I MICROSISMI
Authors: M. GIORGI  , E. ROSINI
Published: June 2021

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ANCORA SULLA VELOCITA' DI PROPAGAZIONE DELLE ONDE SUPERFICIALI PER TRAGITTI SUBATLANTICI. TENTATIVO DI PROSPEZIONE PROFONDA DEL BACINO ATLANTICO, MEDIANTE LE CURVE DI DISPERSIONE DELLE ONDE Lq
Authors: P. CALOI  , L. MARCELLI  , G. PANNOCCHIA
Published: June 2021

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SULLA RAPPRESENTAZIONE IN SUPERFICIE DELLA NATURA DINAMICA DI UNA SCOSSA ALL'IPOCENTRO
Authors: DOMENICO DI FILIPPO
Published: June 2021

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RECENSIONI
Authors: AAVV AAVV
Published: June 2021

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RACCOLTA DI DATI IOSFERICI DEDOTTI DA PROVE DIRETTE DI COLLEGAMENTI R.T. EFFETTUATI SULLA RETE DELL'ESERCITO. PARTE II
Authors: STELIO SILLENI
Published: June 2021

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Automated control procedures and first results from the temporary seismic monitoring of the 2012 Emilia sequence
Authors: Simone Marzorati  , Simona Carannante  , Marco Cattaneo  , Ezio D'Alema  , Massimo Frapiccini  , Chiara Ladina  , Giancarlo Monachesi  , Daniele Spallarossa
Published: June 2021

After moderate to strong earthquakes in Italy or in the surrounding areas, the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute for Geophysics and Volcanology) activates a temporary seismic network infrastructure. This is devoted to integration with the Italian National Seismic Network (RSN) [Delladio 2011] in the epicentral area, thus improving the localization of the aftershocks distribution after a mainshock. This infrastructure is composed of a stand-alone, locally recording part (Re.Mo.) [Moretti et al. 2010] and a real-time telemetered part (Re.Mo.Tel.) [Abruzzese et al. 2011a, 2011b] that can stream data to the acquisition centers in Rome and Grottaminarda. After the May 20, 2012, Ml 5.9 earthquake in the Emilia region (northern Italy), the temporary network was deployed in the epicentral area; in particular, 10 telemetered and 12 stand-alone stations were installed [Moretti et al. 2012, this volume]. Using the dedicated connection between the acquisition center in Rome and the Ancona acquisition sub-center [Cattaneo et al. 2011], the signals of the real-time telemetered stations were acquired also in this sub-center. These were used for preliminary quality control, by adopting the standard procedures in use here (see next paragraph, and Monachesi et al. [2011]). The main purpose of the present study is a first report on this quality check, which should be taken into account for the correct use of these data. […]
Fault-plane solutions from moment-tensor inversion and preliminary Coulomb stress analysis for the Emilia Plain
Authors: Angela Saraò  , Laura Peruzza
Published: June 2021

We investigate the seismicity occurred in the Po area, in the period July 2011-June 1012, by means of moment tensor and we use our set of revised focal mechanisms - computed for M> 3.7 earthquakes - to evaluate Coulomb elastic stress changes in order to detect potential intermediate-distance faults interaction, and the main features of this complex structural system.