bluuebunny/crossref_metadata_2025 huggingface dataset:
The Coronal and Sagittal Parameters before and after Posterior Spinal Fusion with all Pedicle Screw Construct in Adolescent Idiopathic Scoliosis (AIS) Patients and Comparing their Health-Related Outcomes Through SRS-22 Questionnaire
Authors: Chau Wai-Wang , Ng Bobby Kin-Wah , Hung Alec Lik-Hang
Published: June 2021

Background:

Sagittal balance in severe androgen insensitivity syndrome (AIS) patient has been difficult to study due to problems with imaging technique. Abnormal sagittal profiles have been frequently observed in AIS patients presenting as cervical kyphosis, thoracic hypokyphosis, and positive sagittal vertical axis (SVA) off set. The significance of these changes is not understood in these patients. The purpose of this study is to assess the sagittal profile of AIS patients before and after surgery.

Subjects and Methods:

Changes in curve correction in both coronal and sagittal planes before and after surgery. Curve type, Cobb angles, sagittal parameters, and fusion level were analyzed with conventional parameters. Patient outcomes were measured using mobile device friendly Scoliosis Research Society-22 questionnaire online.

Results:

Fourteen patients were recruited. Average age was 16 years (13–36). Postoperation and final follow-up Cobb angles were reduced to 27°, 26°, and 16° and 29°, 28°, and 16°, respectively. In the sagittal plane, the Cobb angles pre- and postoperation and final follow-up are as follows: Cervical lordosis (36.7, 39.1, and 41.9), thoracic kyphosis (33.1, 35.8, and 39.1), lumbar lordosis (51.1, 45.2, and 54.2), SVA (1.3, 1.6, and 0), pelvic tilt (19, 21, and 18), sacral slope (47, 46, and 55), and pelvic tilt (43.7, 45, and 43.5). “Function”, “satisfaction,” and “mean” were significantly improved over the period, particularly between the last seen visit and before surgery.

Conclusions:

Abnormal coronal and sagittal parameters and their changes after surgery are reported in AIS patients. Patients expressed significant improvements in their function abilities and satisfied with clinical management, as well as their general quality of life.
Micro-Core Decompression Combined with Intralesional Zoledronic Acid as a Treatment of Osteonecrosis of Femoral Head
Authors: Ashraf Muhammed , George Jyothis , Sha I. Ibad
Published: June 2021

Background:

Avascular Necrosis / Osteonecrosis of the femoral head is a debilitating condition affecting the hip joint and is one of the most common causes of total hip replacement. The available treatments include pharmacological and surgical options with Total hip arthroplasty (THA) being the mainstay of treatment. We here is studying a novel technique of combining micro core decompression with intra-lesional bisphosphonate as a treatment for osteonecrosis of the hip.

Materials and Methods:

A prospective study of 19 hips was done. There were 11 males and 4 females ranging 42 - 63 years. Four hips were stage I, ten hips were stage IIA, three hips were stage IIb and two hips were stage III. 16 hips (40%) had stage IIb and 24 hips (60%) had stage III ONFH. The minimum period of follow up was 24 months. All patients were assessed according to the Harris Hip Score (HHS). The operative procedure include decompressing the avascular area with drilling then injecting the zoledronic acid locally.

Results:

The mean preoperative modified Harris Hip Score in stage I (n=4), stage IIa (n=10), stage IIb (n=3) and Stage III (n=2) were 81.9, 72.7, 68.8 and 59.2 respectively. The mean postoperative modified Harris Hip Score at two years in stage I, stage IIa, stage IIb and Stage III were 97.3, 91.1, 88.4 and 82.5 respectively.

Conclusion:

We found that the use of micro core-decompression with intra-lesional bisphosphonate will provide higher chances towards hip preservation especially in late cases or cases with larger lesions where core decompression may not be successful.
Network Pharmacology Study of Yuebi Plus Banxia Decoction in Treating Asthma
Authors: Song Wen-Jie , Hao Zheng
Published: June 2021

Objective:

The objective of the study was to study the potential biological mechanism of Yuebi plus Banxia Decoction (YBD) in the treatment of asthma based on network pharmacology.

Materials and Methods:

Literature databases were used to collect information on the chemical components and pharmacokinetics of YBD as comprehensively as possible. According to pharmacokinetic information and effective ingredient screening criteria, effective chemical components of YBD were screened, and the target genes corresponding to the effective components were collected by the ligand prediction method. At the same time, literature databases including five disease target gene databases were used to collect asthma disease target genes. Then, the effective component target network of YBD and the asthma disease target network can be constructed using Cytoscape 3.2.1 software. The core targets of YBD for the treatment of asthma were screened according to topological analysis based on degree parameters. Through the analysis ofKyoto Encyclopedia of Genes and Genomes (KEGG) signal pathway, the main mechanisms of YBD in treating asthma were found out.

Results:

A161 active ingredients of YBD and 136 core targets for the treatment of asthma were screened out. The effective signaling pathways of YBD in the treatment of asthma were mainly focused on ErbB, MAPK, Estrogen, PI3K-Akt, Neurotrophin, Hippo, HIF-1, TGF-, FoxO, Wnt, Chemoking, Toll-like receptor, vascular endothelial growth factor (VEGF), GnRH, and Notch.

Conclusion:

YBD has the characteristics of multiple targets and multiple pathways in the treatment of asthma. Its main biological mechanism is related to ErbB, MAPK, Estrogen, PI3K-Akt, neurotrophin, Hippo, HIF-1, TGF-, FoxO, Wnt, Chemoking, Toll-like receptor, VEGF, GnRH, and Notch.
Correlation bounds for fields and matroids
Authors: Huh June , Schröter Benjamin , Wang Botong
Published: June 2021

Let G be a finite connected graph, and let T be a spanning tree of G chosen uniformly at random. The work of Kirchhoff on electrical networks can be used to show that the events

e_1 \in\rm T

and

e_2 \in\rm T

are negatively correlated for any distinct edges

e_1

and

e_2

. What can be said for such events when the underlying matroid is not necessarily graphic? We use Hodge theory for matroids to bound the correlation between the events

e \in\rm B

, where B is a randomly chosen basis of a matroid. As an application, we prove Mason’s conjecture that the number of

k

-element independent sets of a matroid forms an ultra-log-concave sequence in

k

.
Harmonic quasiconformal mappings between $\mathcal{C}^1$ smooth Jordan domains
Authors: Kalaj David
Published: June 2021

We prove the following result. If

f

is a harmonic quasiconformal mapping between two Jordan domains

D

and

\Omega

having

\mathcal{C}^1

boundaries, then the function

f

is globally Hölder continuous for every

\alpha<1

but it is not necessarily Lipschitz in general. This result extends and improves a classical theorem of S. Warschawski for conformal mappings.
Seasonal variations in natural processesand atmospheric precipitation
Authors: A. V. Descherevsky  , A. Ya. Sidorin
Published: June 2021

To study the nature of seasonal variations in time series measured at the Garm test site, a local model based on the experimental data of atmospheric precipitation penetration into the soil has been proposed. It is intended for filtration of exogenous variations in the data of various time series and a study of statistical structure of different natural processes, including earthquake preparation processes, and the mechanisms of their effect on the biosphere. Using this model, we analyze and compare variations in apparent resistivity and properties of rock moistening. It has been shown that at small current-electrode (AB) separations among all the parameters of water regime, only water saturation of the active soil layer reveals a significant correlation with apparent resistivity variations. When increasing the current-electrode separation, the seasonal variation form varies from quasisinusoidal in the upper layer up to quasi-triangular at the largest investigated depths (maximum separations).
Scientific overview and historical context of the 1811-1812 New Madrid earthquake sequence
Authors: S. E. Hough
Published: June 2021

The central and eastern United States has experienced only 5 historic earthquakes with Mw 7.0, four during the New Madrid sequence of 1811-1812: three principal mainshocks and the so-called «dawn aftershock» following the first mainshock. Much of the historic earthquake research done in the United States has focused on the New Madrid Seismic Zone (NMSZ), because the largest New Madrid earthquakes may represent the archetype for the most damaging earthquakes to be expected in intraplate regions. Published magnitude values ranging from 7.0 to 8.75 have generally been based on macroseismic effects, which provide the most direct constraint on source size for the events. Critical to the interpretation of these accounts is an understanding of their historic context. Early settlments clustered along waterways, where substantial amplification of seismic waves is expected. Analyzing the New Madrid intensity values with a consideration of these effects yields preferred values of Mw 7.2-7.3, 7.0, and 7.4-7.5 for the December, January, and February mainshocks, respectively, and of 7.0 for the «dawn aftershock». These values are consistent with other lines of evidence, including scaling relationships. Finally, I show that accounts from the New Madrid sequence reveal evidence for remotely triggered earthquakes well outside the NMSZ. Remotely triggered earthquakes represent a potentially important new wrinkle in historic earthquake research, as their ground motions can sometimes be confused with mainshock ground motions.
A critical history of British earthquakes
Authors: R. M. W. Musson
Published: June 2021

This paper reviews the history of the study of historical British earthquakes. The publication of compendia of British earthquakes goes back as early as the late 16th Century. A boost to the study of earthquakes in Britain was given in the mid 18th Century as a result of two events occurring in London in 1750 (analogous to the general increase in earthquakes in Europe five years later after the 1755 Lisbon earthquake). The 19th Century saw a number of significant studies, culminating in the work of Davison, whose book-length catalogue was published finally in 1924. After that appears a gap, until interest in the subject was renewed in the mid 1970s. The expansion of the U.K. nuclear programme in the 1980s led to a series of large-scale investigations of historical British earthquakes, all based almost completely on primary historical data and conducted to high standards. The catalogue published by BGS in 1994 is a synthesis of these studies, and presents a parametric catalogue in which historical earthquakes are assessed from intensity data points based on primary source material. Since 1994, revisions to parameters have been minor and new events discovered have been restricted to a few small events.
On historical earthquakes in Switzerland: summary of compilations and investigations
Authors: D. Mayer-Rosa  , G. Schwarz-Zanetti
Published: June 2021

Studies of historical earthquakes in Switzerland are contained in monographs, chronological collections of effects and parametric catalogues. The systematic collection of macroseismic material started with the creation of the Swiss Seismological Commission in 1878. All parametric catalogues since 1975 have been prepared for seismic hazard assessment. The most up-to-date investigation of macroseismic data and compilation into a catalogue (ECOS) was made in the 2002 in context of the re-assessment of seismic hazard for nuclear sites.
Assessing the completeness of Italian historical earthquake data
Authors: M. Stucchi  , P. Albini  , M. Mirto  , A. Rebez
Published: June 2021

The assessment of the completeness of historical earthquake data (such as, for instance, parametric earthquake catalogues) has usually been approached in seismology - and mainly in Probabilistic Seismic Hazard Assessment(PSHA) - by means of statistical procedures. Such procedures look «inside» the data set under investigation and compare it to seismicity models, which often require more or less explicitly that seismicity is stationary. They usually end up determining times (Ti), from which on the data set is considered as complete above a given magnitude (Mi); the part of the data set before Ti is considered as incomplete and, for that reason, not suitable for statistical analysis. As a consequence, significant portions of historical data sets are not used for PSHA. Dealing with historical data sets - which are incomplete by nature, although this does not mean that they are of low value - it seems more appropriate to estimate «how much incomplete» the data sets can be and to use them together with such estimates. In other words, it seems more appropriate to assess the completeness looking «outside » the data sets; that is, investigating the way historical records have been produced, preserved and retrieved. This paper presents the results of investigation carried out in Italy, according to historical methods. First, the completeness of eighteen site seismic histories has been investigated; then, from those results, the completeness of areal portions of the catalogue has been assessed and compared with similar results obtained by statistical methods. Finally, the impact of these results on PSHA is described.
Evidence of historical seismicity and volcanism in the Armenian Highland (from Armenian and other sources)
Authors: A. Karakhanian  , Y. Abgaryan
Published: June 2021

This work presents a summary on the development of studies of historical earthquakes in Armenia and adjacent parts of Turkey and Iran. Since ancient times, this region has been an arena where active geodynamic and seismic history intermingled with no less active and dynamic evolution of human cultures and societies. A long-term historical record in this region beginning as early as the 8th century B.C. provides abundant evidence that can make an inestimable contribution to studies of historical seismicity and volcanism in the area. We discuss the main research methodology and sources used, and dwell on the principal catalogues of historical earthquakes compiled to date.
History of earthquake studies in Russia
Authors: R. Tatevossian
Published: June 2021

To evaluate the completeness of modern knowledge on historical seismicity it is necessary to know the general geopolitical and socio-cultural background in the country. It determines the possibility to record the evidence of an earthquake and conserve the record in original form for a long time-period. The potential duration of historical earthquake study in Russia is assessed based on these considerations. Certain stages of earthquake study in Russia have been detected. Specific problems of seismicity studies of low active areas are discussed as an example of Russian platform. The value of each (even moderate magnitude) event becomes crucial for seismic hazard assessment in such territories. A correct identification of event nature (tectonic earthquake or exogenous phenomena - landslides, karsts, etc.) is practically impossible without using primary sources with detailed descriptions. Occurrence of modern earthquakes can be used to assess the accuracy of historical seismicity knowledge.
Local stresses, dyke arrest and surface deformation in volcanic edificesand rift zones
Authors: A. Gudmundsson  , L. S. Brenner
Published: June 2021

Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes) that are opened by magmatic overpressure. While (inferred) dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces) infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear) strength while the same strength is not exceeded at the (arrested) dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses), layers with relatively high dyke-normal compressive stresses (stress barriers), and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward inversion of surface geodetic data may lead to unreliable geometries of arrested dykes in active rift zones and volcanic edifices.
The revised aeromagnetic anomaly map of Italy
Authors: F. Caratori Tontini  , P. Stefanelli  , I. Giori  , O. Faggioni  , C. Carmisciano
Published: June 2021

This paper presents the revised aeromagnetic anomaly map of Italy and its surrounding seas, projected at reference altitude of 2500 m and geomagnetic epoch 1979.0. The magnetic data set used for the map compilation is composed of the total intensity field data acquired partly during the aeromagnetic surveys performed by the Italian National Oil Company (Agip - Direzione Esplorazione Idrocarburi) between 1971 and 1980, and during the new surveys committed by the Geophysical Corporate Services of Eni Spa - Exploration & Production Division in the years 2001-2002. In both campaigns the recorded data were very dense and uniformly distributed over the examined area. A detailed re-processing of this data set and a re-organization into a new digital database were carried out. The re-processing was done using modern adequate techniques, obtaining a remarkable exploitation of the data information content. The result is a colour shaded relief map that shows on a large scale many of the structural lineaments of the Italian area. The inclusion of a larger number of data and the subtraction of an appropriate magnetic reference field are the main reasons of an enhancement in the anomaly definition. This new map replaces the previous Agip version, and aims to become the reference aeromagnetic cartography of the Italian area. We think this work will be useful both for researchers interested in large scale tectonic studies, and for anyone interested in the investigation of smaller scale structures, such as volcanic complexes or infra-sedimentary magnetic bodies, as well as for mining research.
A probabilistic seismic hazard assessment for Greece and the surrounding region including site-specific considerations
Authors: T. M. Tsapanos  , P. Mäntyniemi  , A. Kijko
Published: June 2021

A probabilistic approach was applied to map the seismic hazard in Greece and the surrounding region. The procedure does not require any specification of seismic sources or/and seismic zones and allows for the use of the whole seismological record, comprising both historical and instrumental data, available for the region of interest. The new seismic hazard map prepared for Greece and its vicinity specifies a 10% probability of exceedance of the given Peak Ground Acceleration (PGA) values for shallow seismicity and intermediate soil conditions for an exposure time of 50 years. When preparing the map, the new PGA attenuation relation given by Margaris et al. (2001) was employed. The new map shows a spatial distribution of the seismic hazard that corresponds well with the features of shallow seismicity within the examined region. It depicts the level of seismic hazard in which the exceedance of the PGA value of 0.25 g may be expected to occur within limited areas. The highest estimated levels of seismic hazard inside the territory of Greece are found in the Northern Sporades Islands, where PGA values in excess of 0.50 g are reached at individual sites, and in the Zante Island in Western Greece, where PGA values in the range of 0.35 g to 0.40 g are obtained at more numerous localities. High values are also observed in the sea between the Karpathos and Rhodes islands, near the Island of Amorgos (Cyclades Archipelago) and in the Southwestern Peloponnesus. The levels of seismic hazard at the sites of seven Greek cities (Athens, Jannena, Kalamata, Kozani, Larisa, Rhodes and Thessaloniki) were also estimated in terms of probabilities that a given PGA value will be exceeded at least once during a time interval of 1, 50 and 100 years at those sites. These probabilities were based on the maximum horizontal PGA values obtained by applying the design earthquake procedure, and the respective median values obtained were 0.24 g for Athens, 0.28 g for Jannena, 0.30 g for Kalamata, 0.21 g for Kozani, 0.24 g for Larisa, 0.43 g for Rhodes and 0.35 g for Thessaloniki. The probabilities of exceedance of the estimated maximum possible PGA value were also calculated for the cities to illustrate the uncertainty of maximum PGA assessment.
Seismogenesis in Central Apennines, Italy: an integrated analysis of minor earthquake sequences and structural data in the Amatrice-Campotosto area
Authors: P. Boncio  , G. Lavecchia  , G. Milana  , B. Rozzi
Published: June 2021

We present a seismotectonic study of the Amatrice-Campotosto area (Central Italy) based on an integrated analysis of minor earthquake sequences, geological data and crustal rheology. The area has been affected by three small-magnitude seismic sequences: August 1992 (M=3.9), June 1994 (M=3.7) and October 1996 (M=4.0). The hypocentral locations and fault plane solutions of the 1996 sequence are based on original data; the seismological features of the 1992 and 1994 sequences are summarised from literature. The active WSWdipping Mt. Gorzano normal fault is interpreted as the common seismogenic structure for the three analysed sequences. The mean state of stress obtained by inversion of focal mechanisms (WSW-ENE-trending deviatoric tension) is comparable to that responsible for finite Quaternary displacement, showing that the stress field has not changed since the onset of extensional tectonics. Available morphotectonic data integrated with original structural data show that the Mt. Gorzano Fault extends for ~28 km along strike. The along-strike displacement profile is typical of an isolated fault, without significant internal segmentation. The strong evidence of late Quaternary activity in the southern part of the fault (with lower displacement gradient) is explained in this work in terms of displacement profile readjustment within a fault unable to grow further laterally. The depth distribution of seismicity and the crustal rheology yield a thickness of ~15 km for the brittle layer. An area of ~530 km2 is estimated for the entire Mt. Gorzano Fault surface. In historical times, the northern portion of the fault was probably activated during the 1639 Amatrice earthquake (I = X, M~ 6.3), but this is not the largest event we expect on the fault. We propose that a large earthquake might activate the entire 28 km long Mt. Gorzano Fault, with an expected Mmax up to 6.7.
Evaluation of the seismic hazard parameters for selected regions of the world: the maximum regional magnitude
Authors: T. M. Tsapanos
Published: June 2021

Parameters of seismic hazard are estimated by the application of the maximum likelihood method. The technique is based on a procedure which utilizes data of different quality, e.g., the ones where the uncertainty in the assessment of the magnitudes is great and those where the magnitudes are computed with great precision. In other words, the data were extracted from both historical (incomplete) and recorded (complete) files. The historical part of the catalogue contains only the strongest events, whereas the complete part can be divided into several subcatalogues each one assumed to be complete above a specified threshold magnitude. Uncertainty in the determination of magnitudes has also been taken into account. The method allow us to estimate the seismic hazard parameters which are the maximum regional magnitude, Mmax , the activity rate, l, of the seismic events and the well known b-value, the slope of the magnitude-frequency relationship. The parameter b, which is interrelated to b (b = bloge), is also obtained. All these parameters are of physical significance. The mean Return Periods, RP, of earthquakes with a certain lower magnitude M ³ m are also determined. The method is applied in some regions of the circum-Pacific belt, which includes various tectonic features, and where catastrophic earthquakes are known from the historical era. The seismic hazard level is also calculated as a function of the form q(Mmax , RP7.5 ) and a relative hazard scale (defined as an index K) is defined for each seismic region. According to this, the investigated regions are classified into five groups of very low, low, intermediate, high and very high seismic hazard levels. This classification is useful for both theoretical and practical reasons and provides a picture of quantitative seismicity.
New magnetotelluric soundings in the Mt. Somma-Vesuvius volcanic complex: preliminary results
Authors: A. Manzella  , G. Volpi  , A. Zaja
Published: June 2021

During 1997 ten magnetotelluric (MT) soundings were recorded in single-site mode above the Mt. Somma-Vesuvius volcanic area. A first campaign of MT measurements was carried out, during spring, by the researchers of the University of Padua with their MSPM acquisition system. During autumn, the researchers of the International Institute of Geothermal Research (CNR Pisa) with their Phoenix equipment performed a second campaign. A teach site, the horizontal components of the electrical and magnetic fields were recorded in the frequency band between 300-0.003 Hz. The MSPM system could record signals up to the frequency of 800 Hz. Data were recorded at one common site with both the different equipments to verify the compatibility of the two different acquisition systems. The soundings over the area of the volcano's caldera show a continuous morphology of the apparent resistivity and phase curves with small error bars: it means a good correlation between the orthogonal electrical and magnetic fields. The quality of data decreases going further from the caldera and approaching the sources of electromagnetic incoherent noise such as villages, antennas and repeaters. After a very accurate data analysis, the apparent resistivity and phase curves were interpreted with a 1D modelling instead a 2D one as it seems a more appropriate interpretative approach looking at the morphology of the curves and taking into account the 3D geological conditions of the area. The results show an extended conductive structure at a depth of 0.3-1.2 km. It could be connected with a change in the physico-chemical characteristics of the volcano-sedimentary cover (alteration paragenesis and possible hydrothermalism). A 3D MT forward modelling was then used to define the response MT curves for sites above this particular volcanic structure. This approach seems to be very interesting in view of specific interpretative targets, such as dimension and position of the magma chamber, when planning future MT surveys.
An experiment on a sand-dune environment in Southern Venetian coast based on GPR, VES and documentary evidence
Authors: A. Galgaro  , E. Finzi  , L. Tosi
Published: June 2021

The internal structures of some surviving sand dunes and the ancient shore-lines along the coast south of Venice have been investigated integrating Ground Probing Radar (GPR) profiles, Vertical Electrical Soundings (VES) and water conductivity measurements in some boreholes. The GPR penetration depth has been limited (4-5 m,using a 400 MHz antenna) by the high conductivity of salt water saturating pores of the shallow sediments. On the other hand, the excellent spatial resolution of the radar survey provided an estimate of internal dune bedding features, such as cross lamination and forwarding ancient covered coast-lines dated in the Thirties. The interpretation of the data, in particular along one line 360 m long intercepting a sizable sand-dune bank, seems to offer clues to the evolutional history of the coast line and the depth of transition from fresh-water to brackish-salt water. The water table was detected with electrical measurements and direct observations in boreholes, whereas the transition between fresh and salt water (brackish water) was pointed out indirectly by the high energy absorption and total back-reflection of the EM waves, encountered at this boundary, and directly by the strong decrease in VES resistivity values.
Magnetic stratigraphy of the Villafranchian type-section:(Villafranca d'Asti, Italy)
Authors: P. Boano  , D. Bormioli  , F. Carraro  , R. Lanza
Published: June 2021

A detailed magnetostratigraphic investigation has been carried out along the section of the Fornace RDB quarry (Villafranca d'Asti, NW Italy), which is the type-section of the Villafranchian and has provided many of the land mammal remains used by Azzaroli (1977) to define the Val Triversa faunal unit (zone MN16a). Poorly consolidated clay and clayey silt are the prevailing lithologies and samples were collected with plastic boxes. Isothermal remanent magnetization measurements showed that haematite is the main ferromagnetic mineral and occurs through the section, whereas iron sulphide is subordinate and only occurs in the lower part. Alternating field demagnetization usually succeeded in isolating a stable component and was used to derive the characteristic remanence by demagnetizing the specimens at 4 to 7 steps in the range 15 to 80 mT. The magnetic fabric was investigated by measuring the anisotropy of the magnetic susceptibility. It was always well defined and characterized by a horizontal foliation matching the bedding plane. The anisotropy of isothermal remanent magnetization was measured on some specimens and yielded fully comparable results. This consistency shows that detrital haematite carries the primary magnetization in these sediments and explains the 20° inclination shallowing of the site mean palaeomagnetic direction. Only one reverse to normal polarity transition has been detected and a direct correlation with the GPTS reference scale of Cande and Kent (1992, 1995) is thus not possible. The age of the Triversa fauna has been much debated in recent literature. Some authors have recently suggested that it is transitional between Ruscinian and Villafranchian, i.e. a little older than previously assumed. According to this hypothesis, the lower part of the RDB section would correlate to the chron C2Ar (upper Gilbert) and the upper part to the chron C2An.3n (lower Gauss), whereas according to the traditional interpretation correlation is to one of the polarity inversions within the middle Gauss (Kaena and Mammoth). An independent age constraint based on magnetostratigraphy will only be possible when other Ruscinian and Villafranchian sections are investigated in the same detail and a correlation between palaeosecular variation is established.
Geometry of the Aegean Benioff zones
Authors: M. Knapmeyer
Published: June 2021

The morphology of the Aegean Benioff zone was reconstructed using 1366 hypocentres from the PDE catalogue 1973-1997. Two such zones are identified under the Aegean area, a large one (Main Aegean Subduction, MAS) spanning the whole Hellenic arc and a smaller and younger one under the Western Peloponnesus. The geometry of the MAS suggests that it blocks its own subduction and, therefore, causes the development of the smaller western zone as a result of a step back process in the Pliocene.
Merging aeromagnetic data collected at different levels: the GEOMAUD survey
Authors: D. Damaske
Published: June 2021

As part of the German GEOMAUD-expedition an aeromagnetic survey was carried out in Central Queen Maud Land. The helicopter-borne survey was designed in a conventional form of a regional survey with a spacing of profile-lines of 4.4 km. Due to terrain considerations - surveying from the coast across the mountain ranges to the high altitudes of the polar plateau - the survey was split into two sections flown at different constant levels. Over the coastal part survey elevation was 570 m (above sea level) while for the mountain section 2845 m was chosen. Both survey parts were processed separately. The low level section was upward continued before merging with the high level section. Though this leads to a homogeneous magnetic anomaly map, in some applications it may be more advantageous to present the anomalies of the magnetic field in original survey levels as a simple combined map because small scale features are preserved and can be used in recognizing magnetic units and patterns for geological/geophysical interpretation.
The anatomy of a tornillo: puzzles from three-component measurements at Galeras volcano (Colombia)
Authors: D. Seidl  , M. Hellweg  , H. Rademacher  , D. M. Gomez M.  , R. A. Torres C.
Published: June 2021

Many of the recent ash eruptions of Galeras volcano (Colombia) have been preceded by tornillos. These unusual seismic events of unknown origin have screw-like profiles on seismograms and can last up to several minutes. In March, 1996, a broadband, three-component seismometer station was installed 1.6 km south of Cono, Galeras' active vent. With high quality recordings acquired by this system, and methods which work well with narrow band signals, we investigate the frequency content and polarization properties of two tornillos. They have slighty different predominant frequencies, 3.0420 Hz and 3.0595 Hz which remain highly stable for the entire tornillo duration. The polarization analysis shows that the polarization for the two events also differs slightly but remains constant. Most of their energy is linearly polarized and lies in the horizontal plane. If these waves are taken to be SH waves, the remaining energy is confined to the beginning of the tornillo during its initiation or excitation. The remainder of the tornillo is characterized by exponential decay. These observations provide parameters for the classification of tornillos and constraints for source models.
Listening carefully: unique observations of harmonic tremor at Lascar volcano, Chile
Authors: M. Hellweg
Published: June 2021

During the deployment of Proyecto de Investigación Sismológica de la Cordillera Occidental 94 (PISCO'94) in the Atacama Desert of Northern Chile, a broadband seismic station and a network of three short-period three-component stations were installed around the active volcano Lascar. The resulting data set includes a sequence of harmonic tremor with a fundamental at about 0.63 Hz and up to 30 overtones lasting 18 h. Power spectra and spectrograms of Lascar's harmonic tremor from the various stations demonstrate that the frequencies recorded cannot be explained as path effects, and must therefore be attributed to mechanisms at or near the source. The polarization of the wavefield cannot simply be explained as the propagation of any of the classical types of seismic waves, thus we apply new methods to the data to investigate the narrowband signals of the harmonic peaks. While the amplitude characteristics of these signals cannot be correlated across the network, frequency characteristics of the harmonic wavefield are consistent across stations and components. The tremor's fundamental frequency changes at the same time at all stations, indicating that such changes must be caused at the source. In addition, a change in the frequency of the fundamental, f1, is reflected exactly in the frequencies of the overtones, nf1 and peak-broadening in the power spectrum is the result of shifts in the fundamental frequency. It is therefore unlikely that the overtones are produced as resonances. This spectral behavior indicates rather that the source is some resonance at a single frequency within the magma, magma/gas or gas parts of the volcano whose amplitude exceeds the range for which the assumptions of linear acoustics are valid.
A detailed analysis of some local earthquakes at Somma-Vesuvius
Authors: P. Capuano  , U. Coppa  , G. De Natale  , F. Di Sena  , C. Godano  , C. Troise
Published: June 2021

In this paper, we analyze local earthquakes which occurred at Somma-Vesuvius during two episodes of intense seismic swarms, in 1989 and 1995 respectively. For the selected earthquakes we have computed accurate hypocentral locations, focal mechanisms and spectral parameters. We have also studied the ground acceleration produced by the largest events of the sequences (ML 3.0), at various digital stations installed in the area during the periods of higher seismic activity. The main result is that seismicity during the two swarm episodes presents similar features in both locations and focal mechanisms. Strong site dependent effects are evidenced in the seismic radiation and strong amplifications in the frequency band 10-15 Hz are evident at stations located on the younger Vesuvius structure, with respect to one located on the ancient Somma structure. Furthermore, seismic stations show peak accelerations for the same events of more than one order of magnitude apart.
A repeatable seismic source for tomography at volcanoes
Authors: U. Wegler  , B. G. Lühr  , A. Ratdomopurbo
Published: June 2021

One major problem associated with the interpretation of seismic signals on active volcanoes is the lack of knowledge about the internal structure of the volcano. Assuming a 1D or a homogeneous instead of a 3D velocity structure leads to an erroneous localization of seismic events. In order to derive a high resolution 3D velocity model ofMt. Merapi (Java) a seismic tomography experiment using active sources is planned as a part of the MERAPI (Mechanism Evaluation, Risk Assessment and Prediction Improvement) project. During a pre-site survey in August 1996 we tested a seismic source consisting of a 2.5 l airgun shot in water basins that were constructed in different flanks of the volcano. This special source, which in our case can be fired every two minutes, produces a repeatable, identical source signal. Using this source the number of receiver locations is not limited by the number of seismometers. The seismometers can be moved to various receiver locations while the source reproduces the same source signal. Additionally, at each receiver location we are able to record the identical source signal several times so that the disadvantage of the lower energy compared to an explosion source can be reduced by skipping disturbed signals and stacking several recordings.
The geodynamics of Mt. Etna volcano during and after the 1984 eruption
Authors: S. La Delfa  , G. Patanè  , C. Centamore
Published: June 2021

Data concerning M > 2.5 earthquakes that occurred at Mt. Etna volcano (Sicily, Italy) during the period April 15th - October 29th, 1984 are here presented and discussed. Only those events with reliable focal mechanisms (at least eight polarities) have been considered. Instrumental information comes from local seismic networks run by the University of Catania and the CNRS (Grenoble, France). The results obtained support the hypothesis that the seismicity and the volcanic activity at Mt. Etna are related to a complex stress field, due to the combined effects of the tectonics associated with the interaction between the African and Eurasian plates and the movement of magma into the crust. In particular, we hypothesize that the tectonic forces caused the end of the 1984 eruption, by means of a "locking mechanism".
Luigi Palmieri: first scientific bases for geophysical surveillance in Mt. Vesuvius area
Authors: S. Borgstrom  , M. De Lucia  , R. Nave
Published: June 2021

Luigi Palmieri (Faicchio 1807 -Naples 1896), was appointed Director of the Vesuvius Observatory in 1855. He rea1ized the first model of electromagnetic seismograph and the uninterrupted use at the Observatory of this instrument represented the first step towards a geophysical sensu strictu surveillance of Mt. Vesuvius area. Already at the end of the 18th century, Ascanio Filomarino had built a mechanical seismograph which was ab1e to record the amplitude of the seismic waves, the incoming direction of the earthquake and its starting time. In 1862 Michele Baldacchini proposed to the Neapolitan scientific community a question about the possibility to use the study of precursory signs of the Vesuvian eruptions to inform in advance people living near the vo1cano. Palmieri answered Baldacchini's request, giving proof of extreme far-sightedness from the scientific point of view but, similarly, much concreteness from the practica1 point of view: he described, with modern ideas, the things to do in order to carry out the surveillance in the Mt. Vesuvius area, but concluded thus: "Till we have not the (economic and instrumental) means we have spoken above, I think it is useless to entertain the Academy about the nature and the method of the observations and investigations to be performed".
Coseismic displacement of the 27th September 1997 Umbria - Marche (Italy) earthquakes detected by GPS: campaigns and data
Authors: M. Anzidei  , P. Baldi  , A. Galvani  , A. Pesci  , I. Hunstad  , E. Boschi
Published: June 2021

On September 26,1997 two earthquakes of Mw 5.7 (00.33 GMT) and Mw 6.0 (9.40 GMT), occurred in the Umbria-Marche region (Central Apennines, Italy). The epicentres were located in an area of the Apenninic chain that experienced historical earthquakes up to X degrees of the MCS scale. During the time span 1992-1996, the Italian Istituto Geografico Militare (IGM) set up a new national geodetic network measured by Global Positioning System space geodetic technique, consisting of more than 1200 vertices uniformly distributed on the Italian peninsula and islands. From October 7 to 11, 1997, a short while after the main shocks of the Umbria-Marche seismic sequence, we reoccupied thirteen stations belonging to the IGM and TYRGEONET networks to measure coseismic displacement. The determinations of the post-seismic coordinates at 13 GPS monuments detected significant coseismic displacements. The comparison between the preseismic and postseismic data sets show maximum displacements of 14 cm and 25 cm in the horizontal and vertical components respectively. In this paper, the GPS network, the field work, the data processing procedures and the computed coseismic displacements measured at the geodetic monuments are discussed with the aim to provide a data set useful to the scientific
The Friuli (NE-Italy) tilt/strain gauges and short term observations
Authors: C. Braitenberg
Published: June 2021

The tilt/strainmeter network of the Department of Earth Sciences of the University of Trieste, has by now a long history of records, the Trieste Grotta Gigante horizontal pendulum station having been set up in 1959 and the Friuli tilt/strainmeter stations in 1977. Since then the stations have been continuously recording the strain-rate in one of the most seismic areas of the Alpine arc, giving invaluable information on crustal deformation in a tectonically active area. Although maintaining essentially the same mechanical features from the time of installation, the instrumentation has undergone modernization, in order to apply recent technical developments to the network. This regards mainly data acquisition, which now, except for one station, is digital. The data are all available and are stored in the Deformation-Database of the Department of Earth Sciences. At first a description of the essential technical and mechanical properties of the instrumentation constituting the network is given. The mean power spectrum of all instruments covering five decades is presented, which is a powerful means to compare the quality of different stations. Following theoretical considerations of the expected pre- or coseismic deformation accompanying local events, the observations of those events is presented, which ought to give the greatest signals. The coseismic steps are modeled for those events for which a fault plane solution was available.
Seismic response to stress-strain fields in the lithosphere of Sicily
Authors: G. Barberi  , D. Caccamo  , G. De Luca  , G. Neri  , R. Scarpa
Published: June 2021

Earthquake locations and fault-plane solutions are investigated in Sicily and the surrounding areas, by using local network data for the period 1988-1995, and a recently proposed 3D model of the local crustal structure. The results were used for local-to-regional scale stress inversion and strain tensor computations, after integration by a set of selected focal mechanisms taken from the literature. The area under study appears to be affected by heterogeneity of seismic deformation and the stress field. The contraction-to-extension transition from west to east on a regional scale can find a reasonable explanation in the framework of current geodynamic models, such as those assuming the activity of two main tectonic sources in the South Italy region, e.g., the Africa-Europe north-south slow convergence and the faster eastward roll-back of a westward-dipping Ionian subducting slab (Cinque al., 1993). The analysis of low-magnitude (2.5-4.0) earthquakes permitted us to perform an investigation of local-scale strain heterogeneities in this region and to evidence notable changes in the deformation style when processes at different scales are considered.