bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical features of deep structures of Southern Tuscany (Italy)
Authors: A. Fiordelisi  , R. Mackie  , A. Manzella  , D. Watts  , A. Zaja
Published: June 2021

Over the last six years, magnetotelluric data were acquired at 86 sites covering much of Southern Tuscany. Twenty-four of these sites were acquired in single-site or local-reference mode, whereas 62 were aquired in very-remote-reference mode, with a remote site located on Capraia Island í 40 km from the cost í where the cultural noise is very low. The data modelling showed that Southern Tuscany is characterized by a fairly uniform middle-lower crust that has a resistivity of a few thousand W ·m below 10 km. At shallower depths in the crust, the resistivity is closer to values around 500 W ·m. This uniformity is interrupted only below the Larderello and Mt. Amiata geothermal fields where deep conductive bodies are believed to exist. A general anomalous condition can hence be depicted for this region, with low resistivity values typical of those in tectonically active areas as opposed to more resistive values typical in continental areas. These data and those from other geophysical techniques suggest that these conductive zones may be associated with hot material coming from deeper sources below the geothermal areas.
Parallelisation technique for serial 3D seismic codes: SMS approach
Authors: Arrigo Caserta  , Vittorio Ruggiero  , Maria Pia Busico  , Ivo Oprsˇal
Published: June 2021

We investigate a fast and easy way to parallelise seismological serial codes mainly oriented for simulating the

seismic wave propagation through anelastic dissipative media. Having an efficient modelling tool is important

in both assessing strong ground motion and mitigation of seismic hazard when the site effects are considered,

and in crustal propagation when the crustal geological structures are of interest. Our chosen case study is representative of a set of such seismological 3D problems. The Scalable Modelling System (SMS) tool for parallelization is considered. The IBM SP5 native compiler has been used. Results such as Speed-Up and Efficiency are shown and discussed. SMS can run both in shared and distributed memory environments. The greater advantages of using SMS in such environments become apparent with the utilisation of a higher number of multiprocessor machines arranged in a cluster. We also demonstrate how successful porting from serial to parallel codes is realised by way of minimal instructions (6% of the serial original code only) provided that an ad hoc profiling analysis of the serial code is first performed.
Microseismic feasibility study: detection of small magnitude events (Ml<0.0) for mapping active faults in the Betic Cordillera (Spain)
Authors: Martin Häge  , Manfred Joswig
Published: June 2021

We present the results of the first application of the newly developed concept «Nanoseismic Monitoring» on active
faults in the region close to Murcia, Spain. The aim of this microseismic feasibility study is to test if it is possible
to record small magnitude events (ML<0.0) within a short period of time with surface installations and to investigate
if these events are related to the regional catalog in terms of amount of events. The seismic monitoring
was performed with one small array called the Seismic Navigating System. It consists of one central three component
and three one component seismometers arranged tripartitely around the central station. In the measurement
period of two nights at two different sites we were able to detect 19 microearthquakes down to ML = -2.6. The results
correlate well with the frequency-magnitude distribution of the regional bulletin. This in turn will allow for
estimation of monitoring rates before actual field measurements just from bulletin data. Given an activity rate of
5 to 10 events per night one may map active fault zones within just a few weeks of field campaign.
Rates of Quaternary deformation in the Ouarzazate Basin (Southern Atlas Front, Morocco)
Authors: Àlvar Pastor Castilla  , Antonio Teixell  , María Luisa Arboleya
Published: June 2021

Recent studies have shown that the uplift of the Moroccan Atlas Mountains resulted from a combination of crustal shortening and mantle thermal processes in the interior of the African plate. Within this framework, to gain insight into the dynamics of these processes in recent times, we investigated the nature and rates of the Quaternary deformation in a case field area, namely, the northern Ouarzazate Basin, which contains the best dated records of fan and fluvial terrace deposits of the Atlas system. The area selected is in the southern orogenic front of the High Atlas, where thrusts and fault-related folds have affected a sequence of dated, stepped terraces to varying degrees. Based on cosmogenic nuclide surface exposure dating, we have calculated slow neotectonic deformation rates for the past ~250 ky. We have measured the local rates of structural uplift, yielding 0.2 mm/y in areas of the northern third of the Ouarzazate Basin. We have estimated slip rates at 0.09-0.15 mm/y for the most active fault within the basin. We also document that recent shortening rates (~0.1 mm/y during the last ~250 ky) almost double the average rates from the deformation onset (~0.04 mm/y since the Middle Miocene). These results raise the point of the possible relations between such increases in the deformation rates and the erosional denudation of the Ouarzazate Basin since it became externally drained in the late Pliocene or early Quaternary times.
La sismicita del « Campo fagliato » dell'Aterno
Authors: D. DI FILIPPO  , F. PERONACI
Published: June 2021

After determining the epicentral coordinates, the originhour,
the depth, and the dromochrones of the earthquaqe of June 24, 1958,
at L'Aquila, the physical nature of the quake at its hypocentre is esamined,
thus completing a lifting scheme. The comparison between the seismic, geological,
and tectonic nature of the Aterno valley supplies, together with the
results of the above-mentioned micro-seismic study, a probable explanation
of the faulted field.
Croatian geomagnetic field maps for 2008.5 epoch
Authors: Mario Brkić  , Danijel Šugar  , Marko Pavasović  , Eugen Vujić  , Enio Jungwirth
Published: June 2021

The status of the Croatian Geomagnetic Repeat Stations Network (CGRSN) and Croatian Geomagnetic Network for Field Mapping (CGNFM), completed in 2010, was described. Standard and new survey practices as well as reduction techniques were presented. The CGRSN data reduced in reference to the L'Aquila (AQU), Grocka (GCK) and Tihany (THY) observatories using weighted averages were given for the epoch 2008.5. Detailed pictures of Dalmatia's geomagnetic field of 2008.5 and the corresponding anomaly, obtained from the CGNFM data were shown.
Magnetic Declination Chart 2006 of Europe – produced by the MagNetE Group
Authors: Gerald Duma  , Barbara Leichter  , the MagNetE Group
Published: June 2021

During its 4th Workshop in Helsinki in 2009 the Group for European Repeat Station Surveys, MagNetE, decided to produce a European Declination Chart 2006 which is based on the numerous magnetic repeat station measurements performed in more than 20 countries in Europe. All surveys were conducted within a relatively short period between 2005 and 2007, the data set consists of declination values of 382 repeat stations and the annual mean values of 42 observatories. These first accorded surveys in Europe, providing hundreds of highly accurate magnetic vector data, can be considered the first geomagnetic survey of Europe. The resulting map shows the magnetic declination, which is of main public interest for navigation purposes.

 
ASSOCIAZIONE GEÒF1SICA ITALIANA. Riunione dell'Assemblea Generale dei soci tenuta a Roma nei giorni 17-18 giugno 1953
Authors: AAVV AAVV
Published: June 2021

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RILIEVO GRAVIMETRICO DELLA SICILIA
Authors: E. MEDI  , C. MORELLI
Published: June 2021

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ASSOCIAZIONE GEOFISICA ITALIANA - Convegno del 10-11 giugno 1952
Authors: AAVV AAVV
Published: June 2021

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THE MORPHOLOGY OF GEOMAGNETIC STORMS: AN EXTENSION OF THE ANALYSIS OF Ds, THE DISTURBANCE LOCAL-TIME INEQUALITY
Authors: SYDNEY CHAPMAN
Published: June 2021

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SU UNA POSSIBILITÀ D'IMPIEGO DEL NEFELOMETRO
Authors: FERRUCCIO MOSETTI
Published: June 2021

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The determination of earthquake mechanism, using both longitudinal and traverse waves
Authors: V. I. Keilis-Borok
Published: June 2021

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Sulla "correzione per la gravità" nelle misure delle bilance magnetiche
Authors: A. Norinelli
Published: June 2021

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SULLE MISURE DI TEMPERATURA DEL SOTTOSUOLO NEI FORI TRIVELLATI IN PRESENZA DI ACQUA E SUI RELATIVI RILIEVI FREATIMETRICI IN REGIONI IDROTERMALI
Authors: F. Penta  , b. conforto
Published: June 2021

1 diagrammi mostrano l'andamento della temperatura lungo lasse del forodurante l'avanzamento I dopo elle era cessata da 24 ore l'immissione di acquaf r e d d a nel foro), dopo la perforazione del tappo di cemento al piede della tubazione(il foro era stato svuotalo dell'acqua per provare la buona presa delcemento e successivamente il 29/11, era stalo forato il tappo di cemento senzaimmettere nuova acqua) e dopo un mese e mezzo da quando il foro era statoultimalo. Si può notare: a) la temperatura è andata aumentando con il tempolino a stabilizzarsi a 100"C ili superficie e 135"C al fondo; i bassi valori dellatemperatura riscontrati durante l'avanzamento sono quindi da a t t r i b u i r e alle grandiquantità di acqua fredda immessa nel foro durante l'avanzamento; b) un incrementodella temperatura lungo l'asse del foro fino a ili 100 circa e successivamenteun lievissimo incremento della temperatura con la profondità; i puntidi massima riscontrati nel primo diagramma (foro ancora non tubato) si trovanospostati più in basso rispetto a quelli degli altri due diagrammi (forse a causadella tubazione?); c) Da 300 metri si Ila di nuovo un discreto aumento dellatemperatura con la p r o f o n d i t à ; non si può, pertanto, dire elle la « t e r m a l i t à » cessicon la profondità.
RISULTATI DI SONDAGGI E DI RICERCHE GEOMINERARIE NELL'ISOLA D'ISCHIA DAL 1 9 3 9 AL 1 9 4 3 NEL CAMPO DEL V A P O R E , DELLE ACQUE TERMALI E DELLE « FORZE ENDOGENE » IN GENERALE
Authors: F. Penta  , b. conforto
Published: June 2021

Si comunicano schematicamente i risultati delle osservazioni termichee jreatimetriche e di varie determinazioni e f f e t t u a t e nel periodo1939-43 in 84 pozzi, per la maggior parte appositamente trivellati perindagare stdle caratteristiche idrotermali di quattro contrade dell'isolad'Ischia. Tali indagini, condotte nell'ambito dei lavori geominerarimiranti principalmente alla utilizzazione delle acque termali per forzamotrice ed alla ricerca di vapore acqueo endogeno, anche se incomplete,hanno permesso di trarre qualche idea di massima che qui siriporta sulla fenomenologia interessante le singole zone investigate.
STUDIO DEL GRAVIMETRO WORDEN N. 50 E SUA APPLICAZIONE PER UN RILIEVO GEOFISICO DI DETTAGLIO ALLE FOCI DEL TIMAYO
Authors: c. morelli
Published: June 2021

II gravimetro Worden viene descritto nei particolari, e ne vieneesposta la teoria. Rettifiche e tarature a scopo geofisico vengono esposteper il Worden n. 50. In particolare, ne viene studiata la deriva egli e f f e t t i su di essa degli urti, della pressione e della temperatura:esso risulta compensato per la temperatura, ma ne risente per fortigradienti. La deriva osservata risulta compresa fra — 0,03 e -f- 0,15mgal/ora, col valore medio di -(- 0,05 mgal/ora. Opportune cautelesono quindi necessarie per determinarla ed eliminarne l ' e f f e t t o dairisultati. Con le norme indicate, la precisione di una misura a scopogeo fisico è di 0,03 mgal.A scopo sperimentale, il gravimetro è stato quindi applicato aduna prospezione di dettaglio nella bonifica alle foci del Timavo. Sonostate eseguite 52 stazioni, tutte ripetute due o più volte. Le anomaliesecondo Bouguer consentono di ricavare indicazioni sulla topografiadel fondo roccioso sottostante.
INTERPRETAZIONI GEoFISIChE DI MISURE GEODETICHE
Authors: P. Caloi
Published: June 2021

In questo lavoro l'Autore non ha inteso esporre risultati di suepersonali esperienze; si è preoccupato essenzialmente di compiere unalibera rielaborazione di quanto è stato fatto sull'argomento, specieda parte di ricercatori giaj)j>onesi.
LE SESSE DEL LAGO DI VICO
Authors: g. pannocchia
Published: June 2021

Nel presente lavoro si determinano con i metodi di Defant e diHidaka i periodi delle sesse nni-bi e tri-nodale del lago di Vico, lerelative distanze dei nodi e le curve rappresentanti l'andamento delleampiezze di oscillazione con i metodi detti. Con il metodo indicatoda Neumann si determina di nuovo il periodo della sessa uni-nodale.
SUL MOVIMENTO INIZIALE DELLE ONDE SISMICHE REGISTRATE A ROMA DURANTE IL PERIODO 1938-1943
Authors: D. DI FILIPPO  , L. MARCELLI
Published: June 2021

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SUI POSSIBILI MODI D'OSCILLAZIONE LIBERA DEL LAGO DI BRACCIANO
Authors: PIETRO CALOI
Published: June 2021

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CONTRIBUTI ALLA TEORIA DELLE SESSE IN SISTEMI COMPOSTI DI BACINI LACUSTRI
Authors: GERHARD NEUMANN
Published: June 2021

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LE SESSE NELLE BAIE MARINE E LA QUESTIONE DELLA CORREZIONE DI BOCCA
Authors: GERHARD NEUMANN
Published: June 2021

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MAGNITUDO ED ENERGIA DEI TERREMOTI IN ITALIA
Authors: D. DI FILIPPO  , L. MARCELLI
Published: June 2021

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IL PENDOLO ORIZZONTALE COME CLINOMETRO
Authors: PIETRO CALOI
Published: June 2021

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SUL GRAVIMETRO ATLAS
Authors: CARMELO AQUILIA
Published: June 2021

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SUI NUMERI CARATTERISTICI DELL'ATTIVITÀ SOLARE
Authors: G. RIGHlNI  , G. GODOLI
Published: June 2021

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Geochemical features and effects on deep-seated fluids during the May-June 2012 southern Po Valley seismic sequence
Authors: Francesco Italiano  , Marcello Liotta  , Mauro Martelli  , Giovanni Martinelli  , Riccardo Petrini  , Anna Riggio  , Andrea Luca Rizzo  , Francesca Slejko  , Barbara Stenni
Published: June 2021

A periodic sampling of the groundwaters and dissolved and free gases in selected deep wells located in the area affected by the May-June 2012 southern Po Valley seismic sequence has provided insight into seismogenic-induced changes of the local aquifer systems. The results obtained show progressive changes in the fluid geochemistry, allowing it to be established that deep-seated fluids were mobilized during the seismic sequence and reached surface layers along faults and fractures, which generated significant geochemical anomalies. The May-June 2012 seismic swarm (mainshock on May 29, 2012, M 5.8; 7 shocks M >5, about 200 events 3 > M > 5) induced several modifications in the circulating fluids. This study reports the preliminary results obtained for the geochemical features of the waters and gases collected over the epicentral area from boreholes drilled at different depths, thus intercepting water and gases with different origins and circulation. The aim of the investigations was to improve our knowledge of the fluids circulating over the seismic area (e.g. origin, provenance, interactions, mixing of different components, temporal changes). This was achieved by collecting samples from both shallow and deep-drilled boreholes, and then, after the selection of the relevant sites, we looked for temporal changes with mid-to-long-term monitoring activity following a constant sampling rate. This allowed us to gain better insight into the relationships between the fluid circulation and the faulting activity. The sampling sites are listed in Table 1, along with the analytical results of the gas phase. […]
The INGVterremoti blog: a new communication tool to improve earthquake information during the Po Plain seismic sequence
Authors: Maurizio Pignone  , Concetta Nostro  , Alessandro Amato  , Emanuele Casarotti  , Claudia Piromallo
Published: June 2021

During a seismic sequence, it is extremely important that the population shaken by the earthquakes has continuous and timely information about the ongoing seismic activity. For this reason, a few days after the beginning of the Po Plain sequence, we opened a new informative channel, namely a blog (http://ingvterremoti.wordpress.com), through which we released tens of updates and in-depth scientific explanations on the earthquake sequence, as well as the classical information provided on the INGV web sites. Through the collaboration of Istituto Nazionale di Geofisica e Vulcanologia (INGV) researchers and technicians, we published more than 80 posts about the sequence, to describe ongoing activities during the emergency, and the first scientific results obtained from preliminary data processing. The response of the public was immediately encouraging, and reached its maximum on June 3, 2012, when a Ml 5.1 earthquake was strongly felt in the region previously shaken by the May 20, 2012, Ml 5.9 and the May 29, 2012, Ml 5.8 events. We recorded more than 850,000 views on that particular day, and had more than six million contacts (6,403,843) in the first two months (May 29 to July 29), mostly concentrated in the first 15 days. Even if the number of contacts is surely the main indicator of the effectiveness of a blog, it is important to carry out an in-depth analysis of the audience, to have useful material to further improve this blog. A broader research project could also include cross-media comparisons, taking into account the whole set of social media used by the INGV (YouTube, Twitter, Facebook, Flickr, Apple). Future developments include the creation of new categories and new articles for other regions of Italy, and in-depth scientific articles to explain the results of the research activities. We also plan to find a way to implement the interactions with the public, for answering questions and making comments. The INGVterremoti blog is an original tool to provide information to people, not only during a seismic sequence, but also 'in times of peace', thus contributing to the work of prevention that remains the best defense against earthquakes.
Active tectonics around the Mediterranean region: site studies and application of new methodologies
Authors: Luigi Cucci  , Paolo Marco De Martini  , Eulalia Masana  , Kris Vanneste
Published: June 2021

More than 25 years have passed since the definition of Active Tectonics as "tectonic movements that are expected to occur within a future time span of concern to society", formulated in a milestone book by the National Research Council on this topic (Studies in Geophysics, Active Tectonics, National Academy Press, Washington, D.C. 1986), and those words have still to be considered the most suitable and exhaustive way to explain this branch of the Earth Sciences. Indeed only bridging together basic studies ("tectonic movements"), rates of occurrence ("time span") and hazard assessment ("society") can we fully evaluate ongoing tectonic activity and its associated hazards. The broad Mediterranean Sea region is a paradigmatic area from this point of view, as on one hand this region displays in a relatively limited geographic extent a great variety of tectonic processes such as plate collision, subduction, volcanic activity, large-magnitude earthquakes, active folding and faulting, vertical uplift and/or subsidence. On the other hand, all the above mentioned tectonic processes can potentially affect a total population of about 450 million, mostly concentrated in fast-growing urban areas and/or close to industrial compounds and critical facilities often located nearby hazard sources. […]
Recognition of Pleistocene marine terraces in the southwest of Portugal (Iberian Peninsula): evidences of regional Quaternary uplift
Authors: Paula M. Figueiredo  , João Cabral  , Thomas K. Rockwell
Published: June 2021

Southwest mainland Portugal is located close to the Eurasia-Nubia plate boundary and is characterized by moderate seismicity, although strong events have occurred as in 1755 (Mw≥8), 1969, (Mw 7.9), and more recently in 2007 (Mw 5.9) and 2009 (Mw 5.5), all located in the offshore. No historical earthquakes with onshore rupture are known for this region. At the coastline, high sea cliffs, incised drainages, emergent marine abrasion platforms and paleo sea cliffs indicate that this region is undergoing uplift, although no morphological features were found that could be unequivocally associated with the 1755 mega earthquake. To better understand the recent tectonic activity in this sector of Iberia, it is necessary not only to analyze active structures on land, but also to search for evidence for deformation that may relate to inferred offshore active structures. We thus conducted a study of marine terraces along the coastline to identify regional vertical crustal motions. Several poorly preserved surfaces with thin sedimentary deposits, comprising old beach sediments, were recognized at elevations starting at 2 m elevation and rising inland up to a regional abrasion platform situated at about 120 m a.s.l.. We identified distinct paleo sea level references at several locations at consistent elevations. This terrace sequence is likely Late Pleistocene in age, with individual platforms correlative to MIS 5 high stands and is coherent with a long-term slow uplift of the littoral zone for the southwest of Portugal. Although dating of discrete platforms is an ongoing and difficult task, preliminary correlations of paleo-shoreline elevations suggest that the uplift rate is in the range of 0.1-0.2 mm/yr.
Study of thin clouds at CNR-IMAA Atmospheric Observatory (CIAO)
Authors: Marco Rosoldi  , Pilar Gumà Claramunt  , Fabio Madonna  , Aldo Amodeo  , Ioannis Binietoglou  , Giuseppe D'Amico  , Aldo Giunta  , Lucia Mona  , Nikolaos Papagiannopoulos  , Gelsomina Pappalardo
Published: June 2021

Space-based measurements allow us to study atmospheric variables at global scale, but ground-based observations are necessary for calibration and validation [GCOS, 2006]. Upcoming satellite missions aim at showing the benefit coming from the availability of technological improvements and innovations. However, research is necessary to improve retrieval algorithms of atmospheric variables and to assess the real advances in the knowledge of weather and climate. Quality-controlled vertical profiles of atmospheric key variables provided by ground-based advanced atmospheric observatories represent the optimal basis for the satellite cal/val programs. So far, atmospheric observatories are working towards the development of new observation strategies and the full exploitation of the synergy among active and passive profiling sensors. This is highly relevant for the new generation satellites equipped with multiple sensors on board the same observation platform. [...]
The seismic microzonation of level 3 of Sant’Agata Fossili (northern Italy) based on a multidisciplinary approach
Authors: Giuseppe Di Capua  , Massimo Compagnoni  , Giuseppe Di Giulio  , Marco Marchetti  , Giuliano Milana  , Silvia Peppoloni  , Floriana Pergalani  , Vincenzo Sapia
Published: June 2021

In this paper the results of a detailed seismic microzonation, performed at Sant’Agata Fossili (Piemonte region, northern Italy) are presented. We study the local seismic response of this small village using a level 3, that is the most accurate level following the Italian code of seismic microzonation. The activity steps consist in a gradual widening of knowledge of the different aspects of the amplification phenomena. A multidisciplinary approach has been performed to obtain the local seismic response: including a study of local geology, geophysical and geotechnical characterization of the lithologies, and numerical and experimental analyses. We finally compare the obtained elastic response spectra to the prescribed spectra of the Italian Building Code (in Italian: Norme Tecniche per le Costruzioni). Our results show the geologic and geophysical differences of the subsoil, that produce different local seismic response in terms of amplification factors and acceleration response spectra.
Eruption column height estimation of the 2011-2013 Etna lava fountains
Authors: Simona Scollo  , Michele Prestifilippo  , Emilio Pecora  , Stefano Corradini  , Luca Merucci  , Gaetano Spata  , Mauro Coltelli
Published: June 2021

In this paper, we use calibrated images collected by the video-surveillance system of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, to retrieve the height of the eruption column during the recent Etna explosive activity. The analysis is carried out on nineteen lava fountains from the New South East Crater dataset. The novel procedure described in this work is achieved in three main steps: at first we calibrated the camera, then we selected the images which recorded the maximum phase of the eruptive activity, and finally we applied an appropriate correction to account for the plume projection on the camera line of sight due to the wind. The results show that the column altitudes range between 6 and 9 km (upper limit of the camera system). The comparison with the plume height values estimated from the analysis of several SEVIRI and MODIS satellite images, show a good agreement. Finally, for nine events we also evaluated the thickness of the volcanic plumes in the umbrella region which ranges between 2 and 3 km.
Influence of Indian Ocean high pressure on streamflow variability over southwestern Australia
Authors: Saqib Ur Rehman
Published: June 2021

 

The seasonal and interannual variability of the southwestern Australia streamflow was examined based on re-analysis dataset from the National Centers for Environmental Prediction / National Center for Atmospheric Research, plus monthly streamflow data from 17 meteorological stations obtained from the Department of Water of the Australian Water Resource Council (1976-2008). Significant findings reveal that since the middle of the last century, the early winter (May-August) streamflow variability over southwestern Australia has been associated with variability in the intensity of the Indian Ocean high pressure (IOHP) system, as well as the zonal movement of the high pressure system across the Indian Ocean. Of note, however, the emphasis in the previous studies has linked the ongoing winter drought in western Australia to changes in sea level pressure, both on a local basis and over larger areas. We introduce objective indices for the area-weighted pressure of the IOHP, and the IOHP area-weighted latitude (IOHLT) and longitude (IOHLN) positions. When the IOHP is shifted to the east, there is less streamflow in the southwestern Australian rivers that are examined in this study. The situation is reversed when the IOHP is shifted to the west, when there is more streamflow in the southwestern Australian rivers. The characteristics of the streamflow pattern are determined for the river catchment areas located around the coastal region over southwestern Australia using principal component analysis. The first principal component taken into consideration describes 84.43% of the total variance. The multiple correlation between the loading of the first principal component scores of the streamflow and the IOHP and IOHLN is 0.54, while the correlation between the southern oscillation index is 0.44. Centers of action indices explain 29% of the streamflow variability, while the southern oscillation index explains only of the 19% streamflow variability. This discovery is of real importance for the definition of the physical mechanism of seasonal (May-August) streamflow variability of southwestern Australian and the IOHP.
Krakatau caldera deposits: revisited and verification by geophysical means
Authors: Izumi Yokoyama
Published: June 2021

 

One of the differences between volcanic craters and calderas is that the latter bottoms are flatways filled with caldera deposit with lower density in comparison to country rocks. The 1883 Krakatau eruption affords us important knowledge on caldera formation even if it was not observed with modern sophisticated instruments. First, volcanic activities of the Krakatau Islands before and after the 1883 eruption are reexamined: previous suppositions involving a caldera-forming eruption of the proto-Krakatau prior to 1883 proved to be unsupported by the bathymetric topographies and gravity anomalies on and around the Krakatau Islands. Then, Anak Krakatau is interpreted as a parasitic cone of the main Krakatau volcano. As supplementary knowledge to discussion of caldera deposits, the results of drillings at several calderas in Japan and Mexico are introduced. Mass deficiency of the caldera deposit at Krakatau caldera is estimated by the gravity anomaly observed there and converted to probable volume with suitable density. For quantitative examination of the subsurface structure beneath the Krakatau complex, spatial distributions of seismic S-wave attenuation and Vp/Vs ratios have been already studied by temporary seismological observations and their results have been published. The high ratios of Vp/Vs observed approximately at Krakatau caldera may be attributable to the caldera deposit that is low density and contain much water. As additional remarks, a zone having both the characters, S-wave attenuation and zones of relatively high Vp/Vs ratio, may be a probable magma reservoir centering at a depth of about 10 km.
Short-term seismic crustal deformation of Iran
Authors: Shoja Ansari  , Ahmad Zamani
Published: June 2021

In this paper the short-term seismic deformation of Iran is determined by the earthquake moment tensor summation. The study areas include the Alborz, Kopeh-Dagh, eastern Iran, Makran and Zagros orogenic belts. The spatial distribution and focal mechanisms of the earthquakes delineate the deformation zones. The mean directions of the P and T axes are determined by the equal area projection of the seismic moment tensors. The orientations of the P-axes are dominantly correlated with the NE crustal motion of Iran relative to Eurasia. The average strain rates are calculated in all of the regions. The maximum shear strain and dilatation rates are defined by the eigenvalues of the average strain rate tensors. The dilatation rate indicates that not only the dominant compression but also the subsidiary tension affects the Alborz and Makran orogenic belts. The velocity tensor components discriminate the vertical thickening and thinning of the crust in some regions of Iran. The seismic deformation rates, which are determined by the velocity tensors, are smaller than the geodetic deformation rates. In the high seismic deformation zones, such as the eastern Iran and Alborz, the geodetic deformation rate is comparable with the seismic deformation rate. Our results indicate that the NW Zagros and Kopeh-Dagh have the lowest seismic deformation rates. The seismic shortening rate increases from NW to SE in the Zagros orogenic belt. The seismic deformation orientations are different from the P-axes, probably due to the lateral translation. The maximum percentage of the seismic deformation in the study areas is related to the eastern Iran and the minimum one is related to the Makran orgenic belt. The average shape tensors indicate that the focal mechanisms in the Kopeh-Dagh have the highest internal similarity. The eastern Iran has the largest seismic moment rate, while the central Zagros has the lowest one.
Earthquake geology: science, society and critical facilities
Authors: Christoph Grützner  , Salvatore Barba  , Ioannis Papanikolaou  , Raul Pérez-López
Published: June 2021

Earthquake geology studies the effects, the mechanics and the impacts of earthquakes in the geological environment. Its role is also to decode the fault history, therefore its approach is fault specific and its outcomes are of decisive value for seismic hazard assessment and planning. The term Earthquake geology includes aspects of modern instrumental studies, tectonics and structural geology, historical surface deformation and tectonic geomorphology, whereas paleoseismology is considered part of earthquake geology [...].
Crustal velocity structure of the Deccan Volcanic Province, Indian Peninsula, from observed surface wave dispersion
Authors: Gaddale Suresh  , Satbir S. Teotia  , Sankar N. Bhattacharya
Published: June 2021

Through inversion of fundamental mode group velocities of Love and Rayleigh waves, we study the crustal and subcrustal structure across the central Deccan Volcanic Province (DVP), which is one of the world’s largest terrestrial flood basalts. Our analysis is based on broadband seismograms recorded at seismological station Bhopal (BHPL) in the central India from earthquakes located near west coast of India, with an average epicentral distance about 768 km. The recording station and epicentral zone are situated respectively on the northern and southern edges of DVP with wave paths across central DVP. The period of group velocity data ranges from 5 to 60 s for Rayleigh waves and 5 to 45 s for Love waves. Using the genetic algorithm, the observed data have been inverted to obtain the crust and subcrustal velocity structure along the wavepaths. Using this procedure, a similar velocity structure was also obtained earlier for the northwestern DVP, which is in the west of the present study region. Comparison of results show that the crustal thickness decreases westward from central DVP (39.6 km) to northwestern DVP (37.8 km) along with the decrease of thickness of upper crust; while the thickness of lower crust remains nearly same. From east to west S-wave velocity in the upper crust decreases by 2 to 3 per cent, while P-wave velocity in the whole crust and subcrust decreases by 3 to 6 per cent. The P- and S-wave velocities are positively correlated with crustal thickness and negatively correlated with earth’s heat flow. It appears that the elevated crustal and subcrustal temperature in the western side is the main factor for low velocities on this side.
Preface
Authors: Domenico Di Mauro
Published: June 2021

The following collection of papers is dedicated to geophysical research and experiments conducted in the polar regions of the Earth, during a period centered around the last third International Polar Year (IPY, 2007-2009) and extending into succeeding years. The issues celebrating the IPY are intended to stimulate interest in the physical processes occurring at the polar regions, with the involvement of all the nations that collaborate and play key roles in these remote areas. [...]
Detection of Volcanic Plumes by GPS: the 23 November 2013 Episode on Mt. Etna
Authors: Massimo Aranzulla  , Flavio Cannavò  , Simona Scollo
Published: June 2021

The detection of volcanic plumes produced during explosive eruptions is important to improve our understanding on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve volcanic plumes is one of the new challenges of the last years in volcanic plume detection. In this work, we analyze the Signal to Noise Ratio (SNR) data from 21 permanent stations of the GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, that are located on the Mt. Etna (Italy) flanks. Being one of the most explosive events since 2011, the eruption of November 23, 2013 was chosen as a test-case. Results show some variations in the SNR data that can be correlated with the presence of an ash-laden plume in the atmosphere. Benefits and limitations of the method are highlighted.
Passive degassing at Nyiragongo (D.R. Congo) and Etna (Italy) volcanoes
Authors: Sergio Calabrese  , Sarah Scaglione  , Silvia Milazzo  , Walter D'Alessandro  , Nicole Bobrowski  , Giovanni Bruno Giuffrida  , Dario Tedesco  , Francesco Parello  , Mathiew Yalire
Published: June 2021

Volcanoes are well known as an impressive large natural source of trace elements into the troposphere. Etna (Italy) and Nyiragongo (D.R. Congo) are two stratovolcanoes located in different geological settings, both characterized by persistent passive degassing from their summit craters. Here, we present some results on trace element composition in volcanic plume emissions, atmospheric bulk deposition (rainwater) and their uptake by the surrounding vegetation, with the aim to compare and identify differences and similarities between these two volcanoes. Volcanic emissions were sampled by using active filter-pack for acid gases (sulfur and halogens) and specific teflon filters for particulates (major and trace elements). The impact of the volcanogenic deposition in the surrounding of the crater rims was investigated by using different sampling techniques: bulk rain collectors gauges were used to collect atmospheric bulk deposition, and biomonitoring technique was carried out to collect gases and particulates by using endemic plant species. The estimates of the trace element fluxes confirm that Etna and Nyiragongo are large sources of metals into the atmosphere, especially considering their persistent state of passive degassing. The large amount of emitted trace elements has a strong impact on the close surrounding of both volcanoes. This is clearly reflected by in the chemical composition of rainwater collected at the summit areas both for Etna and Nyiragongo. Moreover, the biomonitoring results highlight that bioaccumulation of trace elements is extremely high in the proximity of the crater rim and decreases with the distance from the active craters.
Reappraising a wartime earthquake: the October 3, 1943 event in the southern Marches (central Italy)
Authors: Andrea Tertulliani  , Viviana Castelli  , Antonio Rossi  , Maurizio Vecchi
Published: June 2021

The earthquake of October 3, 1943, is an important event for characterization of hazard in central Italy, but none of the earlier studies provide an exhaustive description of its effects. The context in which the earthquake occurred was very complex and many relevant records were not available for consultation when the studies were made. This study set out to improve our understanding of the earthquake and its effects by giving special care to the interpretative problems deriving from the peculiar historical and seismological context of the 1943 earthquake, with reference to the possible interactions between earthquake damage and war damage, and between the effects of the 1943 earthquake and those of other local earthquakes occurred between 1936 and 1951. The historical data set collected by earlier studies was critically revised and more data were sought in repositories that had not been previously considered. The number of localities for which a macrosesmic intensity can be assessed increased from 131 to 170. All intensity values were reassessed; from these we calculate a new macroseismic magnitude Mw 5.5 of the October 3, 1943, earthquake.
Processing of noisy magnetotelluric time series from Koyna-Warna seismic region, India: a systematic approach
Authors: Ujjal K. Borah  , Prasanta K. Patro  , Vaddeboina Suresh
Published: June 2021

Rolling array pattern broad band magnetotelluric (MT) data was acquired in the Koyna-Warna (Maharashtra, India) seismic zone during 2012-14 field campaigns. The main objective of this study is to identify the thickness of the Deccan trap in and around the Koyna-Warna seismic zone and to delineate the electrical nature of the sub-basalt. The MT data at many places got contaminated with high tension power line noise due to Koyna hydroelectric power project. So, in the present study an attempt has been made to tackle this problem due to 50 Hz noise and their harmonics and other cultural noise using commercially available processing software MAPROS. Remote site was running during the entire field period to stand against the cultural noise problem. This study is based on Fast Fourier Transform (FFT) and mainly focuses on the behaviour of different processing parameters, their interrelations and the influences of different processing methods concerning improvement of the S/N ratio of noisy data. Our study suggests that no single processing approach can give desirable transfer functions, however combination of different processing approaches may be adopted while processing culturally affected noisy data.
Evaluation of a global model of ionospheric slab thickness for foF2 estimation during geomagnetic storm
Authors: Buldan Muslim  , Haris Haralambous  , Christina Oikonomou  , Sefria Anggarani
Published: June 2021

This study aims to evaluate the performance of the global model of ionospheric slab thickness (GMIST) in terms of F2 layer critical frequency (foF2) estimation during geomagnetic disturbed conditions. Hourly values of foF2 as obtained from ionosonde stations located at equatorial, low- and mid-latitude regions are compared with the corresponding GMIST and IRI-STORM modeled values. For this purpose, the correlation coefficient, daily mean, root mean square error and improvement percentage are calculated at different regions and geomagnetic disturbance levels. The results show that GMIST is more accurate than IRI-STORM model in terms of foF2 estimation at low- and mid-latitude regions, while at equatorial areas GMIST is less accurate during geomagnetically disturbed and quiet conditions.
Annex 2 to: Passive Degassing at Nyiragongo (D.R. Congo) and Etna (Italy) Volcanoes.
Authors: Sergio Calabrese  , Sarah Scaglione  , Silvia Milazzo  , Walter D'Alessandro  , Nicole Bobrowski  , Giovanni Bruno Giuffrida  , Dario Tedesco  , Francesco Parello  , Mathiew Yalire
Published: June 2021

Plumes [...]
Resolving high frequency anomalies of gas cloud using full waveform inversion
Authors: Srichand Prajapati  , Deva Ghosh
Published: June 2021

High resolution models with structurally improved results significant to the physical properties of rocks in geologically complex areas require advance modeling methodologies. Low frequencies are required to understand the geological properties of the rocks while high frequencies is needed to address the structural challenges. Recent industry success in inversion have shown the accurate and robust results for the low frequencies. In this work, we provide a strategy to resolve geologically complex area such as gas cloud (at high frequencies) using full waveform inversion (FWI) based on 2D wave equation. Our contribution here, is the improvement in FWI imaging by: (i) solving the wave field equation to recover high resolution inversion results which is consistence to physical properties and shows structural enhancements; (ii) estimating the distribution of local minima which is largely affected by initial velocity model. To validate our approach, we demonstrate algorithms on synthetic gas cloud model.
Gravity field models derived from the second degree radial derivatives of the GOCE mission: a case study
Authors: Alexander N. Marchenko  , Dmitriy A. Marchenko  , Alexander N. Lopushansky
Published: June 2021

The GOCE satellite mission is one of the main achievements of the satellite geodesy for the Earth’s gravitational field recovery. Three different approaches have been developed for the estimation of harmonic coefficients from gradiometry data measured on board of GOCE-satellite. In this paper a special version of the space-wise method based on the second method of Neumann for fast determination of the harmonic coefficients Cnm, Snm of the Earth’s gravitational potential is given based on the radial gravity gradients of the EGG_TRF_2 product, except of two polar gaps filled by radial gradients from the EGM2008 gravity model. In the pre-processing stage GOCE-based second degree radial derivatives were averaged to the regular grid through Kalman static filter with additional Gaussean smoothing of residual radial derivatives. All computations are made by iterations. As the first step the determination of the preliminary NULP-01S model up to degree/order 220 derived from the Gaussean grid of the GOCE radial derivatives with respect to the WGS-84 reference field was developed based only one of the radial gradients EGG_TRF_2 in the EFRF-frame. In the second iteration the same algorithm is applied to build the NULP-02S gravity field model up to degree/order 250 using the same Gaussean grid with respect to the NULP-01S reference field. The NULP-02S model was verified by means of applying various approaches for the construction of the gridded gravity anomalies and geoid heights in the Black sea area using processing of datasets from six altimetry satellite missions. Comparison of different models with GNSS-levelling data in the USA area demonstrates the independent verification of achieved accuracy of the constructed NULP-02S Earth’s gravity field model.
The TOMO-ETNA experiment: an imaging active campaign at Mt. Etna volcano. Context, main objectives, working-plans and involved research projects
Authors: Jesús M. Ibáñez  , Janire Prudencio  , Alejandro Díaz-Moreno  , Domenico Patanè  , Giuseppe Puglisi  , Birger-Gottfried Lühr  , Francisco Carrión  , Juan José Dañobeitia  , Mauro Coltelli  , Francesca Bianco  , Edoardo Del Pezzo  , Torsten Dahm  , Veronica Willmott  , Valérie Mazauric
Published: June 2021

The TOMO-ETNA experiment was devised to image of the crust underlying the volcanic edifice and, possibly, its plumbing system by using passive and active refraction/reflection seismic methods. This experiment included activities both on-land and offshore with the main objective of obtaining a new high-resolution seismic tomography to improve the knowledge of the crustal structures existing beneath the Etna volcano and northeast Sicily up to Aeolian Islands. The TOMO ETNA experiment was divided in two phases. The first phase started on June 15, 2014 and finalized on July 24, 2014, with the withdrawal of two removable seismic networks (a Short Period Network and a Broadband network composed by 80 and 20 stations respectively) deployed at Etna volcano and surrounding areas. During this first phase the oceanographic research vessel “Sarmiento de Gamboa” and the hydro-oceanographic vessel “Galatea” performed the offshore activities, which includes the deployment of ocean bottom seismometers (OBS), air-gun shooting for Wide Angle Seismic refraction (WAS), Multi-Channel Seismic (MCS) reflection surveys, magnetic surveys and ROV (Remotely Operated Vehicle) dives. This phase finished with the recovery of the short period seismic network. In the second phase the Broadband seismic network remained operative until October 28, 2014, and the R/V “Aegaeo” performed additional MCS surveys during November 19-27, 2014. Overall, the information deriving from TOMO-ETNA experiment could provide the answer to many uncertainties that have arisen while exploiting the large amount of data provided by the cutting-edge monitoring systems of Etna volcano and seismogenic area of eastern Sicily.
P-wave scattering and the distribution of heterogeneity around Etna volcano
Authors: Toni Zieger  , Christoph Sens-Schönfelder  , Joachim R.R. Ritter  , Birger-Gottfried Lühr  , Torsten Dahm
Published: June 2021

Volcanoes and fault zones are areas of increased heterogeneity in the Earth crust that leads to strong scattering of seismic waves. For the understanding of the volcanic structure and the role of attenuation and scattering processes it is important to investigate the distribution of heterogeneity. We used the signals of air-gun shots to investigate the distribution of heterogeneity around Mount Etna. We devise a new methodology that is based on the coda energy ratio which we define as the ratio between the energy of the direct P-wave and the energy in a later coda window. This is based on the basic assumption that scattering caused by heterogeneity removes energy from the direct P-waves. We show that measurements of the energy ratio are stable with respect to changes of the details of the time windows definitions. As an independent proxy of the scattering strength along the ray path we measure the peak delay time of the direct P-wave. The peak delay time is well correlated with the coda energy ratio. We project the observation in the directions of the incident rays at the stations. Most notably is an area with increased wave scattering in the volcano and east of it. The strong heterogeneity found supports earlier observations and confirms the possibility to use P-wave sources for the determination of scattering properties. We interpret the extension of the highly heterogeneous zone towards the east as a potential signature of inelastic deformation processes induced by the eastward sliding of flank of the volcano.