scholarly journals Magnetic signatures of subsurface faults on the northern upper flank of Mt Etna (Italy)

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Rosalba Napoli ◽  
Gilda Currenti ◽  
Antonino Sicali
Keyword(s):  
Source Parameters ◽  
Magma Ascent ◽  
Magnetic Survey ◽  
Tectonic Structures ◽  
Near Surface ◽  
North East ◽  
The North ◽  
3D Euler Deconvolution ◽  
Mt Etna ◽  
Structural Indices

A ground magnetic study was performed on the northern upper flank of Mt. Etna to provide new insights into subsurface volcano-tectonic structures. The high resolution magnetic survey was focused on the main structures of Piano delle Concazze, a large flat area dominated by the North- East crater and bounded by the rim of the Valle del Leone depression and the extremity of the North- East Rift. More than 2,500 measurements were gathered with a sampling step of about 3 m covering an area of about 0.2 km2. The total-intensity anomaly field shows the presence of intense South- North aligned maxima related to shallow geological structures affecting this area. Filtering techniques and 2.5D modeling have been applied for the determination of the magnetic source parameters. In order to distinguish the near surface structure, filters of the vertical derivatives, Butterworth high-pass and the tilt derivative were used. The 3D Euler deconvolution has been applied to estimate the depth and the structural indices of the causative sources. The calculated structural indices, that express the geometrical nature of the source, are in agreement with forward modeling. They show that the area is mainly affected by subvertical normal fault and the estimated depth of magnetic sources ranges between 10 m and 40 m. Our total field magnetic survey shows that characteristic magnetic anomalies are related to fault zones in the Piano delle Concazze that are well consistent with the local tectonics. The subsurface structures that have been detected allowed to delineate the general structural framework of the area. In particular, it was possible to clarify that these structures seem to be not deep rooted and consequently they can hardly act as preferential pathways for magma ascent.

scholarly journals Fault source investigation of the 6 December 2016 MwMw 6.5 Pidie Jaya, Indonesia, earthquake based on GPS and its implications of the geological survey result

2020 ◽  
Vol 14 (4) ◽  
pp. 405-412
Author(s):  
Endra Gunawan ◽  
Takuya Nishimura ◽  
Susilo Susilo ◽  
Sri Widiyantoro ◽  
Nanang T. Puspito ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Source Parameters ◽  
Secondary Effects ◽  
Near Surface ◽  
Morphological Attributes ◽  
Ground Shaking ◽  
The North ◽  
Coulomb Failure ◽  
North And South ◽  
Fault Source

AbstractOn 6 December 2016 at 22:03 UTC, a devastating magnitude 6-class strike-slip earthquake occurred along an unidentified and unmapped fault in Pidie Jaya, northern Sumatra. We analysed the possible fault using continuous Global Positioning System (GPS) observation available in the region. In our investigation, we searched for the fault source parameters of the north- and south-dipping left-lateral faults and the west- and east-dipping right-lateral faults. We identified that the fault responsible for the earthquake was located offshore, with a southwest-northeast direction. We also computed the Coulomb failure stress and compared the result with the distribution of the aftershocks. In this study, we demonstrated that the result of the geological field survey conducted soon after the mainshock was attributed to the secondary effects of ground shaking and near-surface deformation, and not surface faulting. The newly identified offshore fault proposed by this study calls for further investigation of the corresponding submarine morphological attributes in this particular region.

scholarly journals Magnetic Survey at the Roman Military Camp of el Benian in Mauretania Tingitana (Morocco): Results and Implications

2020 ◽  
Vol 13 (1) ◽  
pp. 28
Author(s):  
Francesco Martorella
Keyword(s):  
Roman Empire ◽  
North Africa ◽  
Geophysical Survey ◽  
Magnetic Survey ◽  
North East ◽  
The North ◽  
Military Camp ◽  
Building Activity ◽  
Economic Studies

The topic of military settlements and the role of troops in the northern provinces of North Africa during the age of the Roman Empire has recently gained a strong interest in historical, archaeological, epigraphical, and economic studies. In particular, at Mauretania Tingitana (in the north-east area of modern-day Morocco), the presence of numerous military camps in the Early and Later Roman Empire has now been assessed. In this framework, the present work deals with the geophysical survey, by means of magnetometry, at the site of el Benian, where the largest military camp is located. In particular, the magnetic survey has highlighted the organization of the camp, almost totally unknown previously. The result of the magnetic survey has confirmed intense building activity over the centuries and made it possible to identify and characterize the structures typical of a military field.

scholarly journals Deep structure of the Anapa flexural-rupture zone, Western Caucasus

2019 ◽  
pp. 3-11
Author(s):  
E. A. Rogozhin ◽  
A. V. Gorbatikov ◽  
Yu. V. Kharazova ◽  
M. Yu. Stepanova ◽  
J. Chen ◽  
...  
Keyword(s):  
Deep Structure ◽  
Sedimentary Cover ◽  
Western Caucasus ◽  
Tectonic Structures ◽  
Deep Roots ◽  
Near Surface ◽  
North West ◽  
The North ◽  
Deep Faults ◽  
Tectonic Zones

In the period from 2007 to 2017 complex geological and geophysical studies were carried out in the three largest flexural-rupture fault zones in the North-West Caucasus (Anapa, Akhtyrka and Moldavan). The micro-seismic sounding (MSM) was used as the main geophysical method. Studies with the help of MSM allowed us to identify the features of the deep structure of the earth’s crust in the study area and to associate them with specific tectonic structures on the surface.The binding was carried out by harmonizing the results of the MSM and the parameters of the section of the sedimentary cover and crustal boundaries according to the drilling data and the work previously performed by the reflected wave method (MOVZ). It was found that the Anapa flexure and longitudinal tectonic zones have clear deep roots, and also separate the pericline of the North-Western Caucasus from the Taman Peninsula and from the lowered blocks of the Northern slope of the folded system.Faults in the study area are divided into: (1) deep faults of the Caucasian stretch, penetrating into the lower crust and even to the upper mantle, and (2) near-surface faults, do not extend to the depths beyond the thickness of the sedimentary cover. The seismogenic role of these tectonic disturbances in the studied seismically active region has been determined.

Un diatrème phréatomagmatique montérégien dans les Appalaches du Québec

1996 ◽  
Vol 33 (5) ◽  
pp. 649-655
Author(s):  
David Morin ◽  
Michel Jébrak ◽  
Robert Marquis
Keyword(s):  
Surface Water ◽  
Country Rock ◽  
Near Surface ◽  
Metasedimentary Rocks ◽  
North East ◽  
The North ◽  
Devonian Age ◽  
Fault Network ◽  
Alkaline Lamprophyres ◽  
East West

A subcircular positive magnetic anomaly and breccias affecting a basanite and its country-rock metasedimentary rocks reveal the presence of a diatreme with a diameter of approximately 420 m, at Eastman, in the Quebec Appalachians. The post-Middle Devonian age, the position in the line of the Monteregian plutons, and the basanite composition, which is comparable to that of the Cretaceous Monteregian alkaline lamprophyres, suggest that the diatreme is related to the Monteregian magmatism. It is located at the junction of two orthogonal tectonic corridors: the north-north-east Baie Verte – Brompton line and an east−west fault network along the prolongation of the Ottawa−Bonnechère Graben. These structures are zones of weakness that probably served as a conduit for the ascending magma and near-surface water to trigger phreatomagmatic eruptions.

scholarly journals CRUST AND UPPER MANTLE IN THE ZONE OF JUNCTION BETWEEN THE CENTRAL ASIAN AND PACIFIC FOLD BELTS

2021 ◽  
Vol 40 (5) ◽  
pp. 16-32
Author(s):  
A.M. Petrishchevsky ◽  
Keyword(s):  
Upper Mantle ◽  
Deep Structure ◽  
Sedimentary Basins ◽  
Density Contrast ◽  
Tectonic Structures ◽  
Crust And Upper Mantle ◽  
North East ◽  
The North ◽  
The Pacific ◽  
Amurian Plate

Spatial distributions of gravity sources and density contrast of geological media, which is reflected by the values of parameter μz , into the crust and upper mantle of Northeast China are analyzed. Features of rheological layering of the tectonosphere and deep spatial relationships of tectonic structures (cratonic blocks, marginal terranes, and sedimentary basins) are defined. In the density contrast distributions the formal signs of Paleozoic subduction of the North-China Craton and Mesozoic subduction of the Pacific Plate under the Amurian Plate were revealed. Crustal deformations are in sharp contrast with upper mantle deformations in structural planes resulting from different directions of tectonic stresses in the Paleozoic and Mesozoic. Thrusting of marginal terranes (Jamusi, Khanka) over the Amurian Plate lithosphere is revealed. Rheology and deep structure of North East China bear many similarities to other regions of the Pacific western margin in Asia and Australia.

scholarly journals ILPYRSKOE EARTHQUAKE March 13, 2013 with Mwreg=5.8, ML=6.2, КS=13.9, I0p=8 (Kamchatsky Isthmus)

2019 ◽  
pp. 343-361 ◽  
Author(s):  
Y. Kugaenko ◽  
S. Drosnina ◽  
Vadim Saltykov ◽  
V. Pavlov ◽  
A. Lander ◽  
...  
Keyword(s):  
Focal Mechanism ◽  
Moment Tensor ◽  
Great Length ◽  
P Waves ◽  
Near Surface ◽  
Real Time Processing ◽  
North East ◽  
The North ◽  
Minimum Number ◽  
Two Stages

The strong (Mwreg=5.8, ML=6.2) near-surface seismic event (Ilpyrskoye earthquake) occurred at 03h12m on 13 March, in the Kamchatka Isthmus. It was the strongest earthquake between 1962 and 2013 for this area. The greatest macroseismic effect was observed at a distance of ~30 km, I=6–7 on the scale MSK-64. We used two independent methods for determining its regional focal mechanism: 1) regional moment tensor in-version using broadband waveforms; 2) solution based on polarities of the P waves. The results are similar: the focal mechanism of Ilpyrskoye earthquake is thrust faulting with strike-slip component; the compression axis is subhorizontal and is oriented in the north-east – south-west direction. The mechanisms for the two strongest aftershocks were also identified, as a result, a change in focal movements during the aftershock process was revealed.The analysis of the aftershock process which consists of two stages with different de-cay character was performed. The process lasted ~ 75 days. About 200 aftershocks ML=3.0–5.7 (КS=7.5–12.9) were recorded, hypocenter depth estimations vary from 0 to 10 km for about 80 % of them. The strongest aftershock was on May 6, 2013 with ML=5.7, Mwreg=4.8, at which the change in focal movements occurred. According to the results of near real time processing, aftershock cloud of Ilpyrskoye earthquake had a pronounced linearity and a great length, which was an artifact. The main cause of the artifact is the minimum number of stations involved in determining the hypocenters of most aftershocks and their quasi-linear disposition. The confidence areas within which solutions are equivalent are shown. We concluded that Ilpyrskoye earthquake is a serious argument that the area of compression between the Okhotsk and North American plates is extended further to the east and the border passes through the Kamchatka Isthmus

scholarly journals Electromagnetic Measurements for Monitoring Molybdenum Contamination in Near-Surface Survey

2015 ◽  
Vol 19 (2) ◽  
pp. 107-111 ◽  
Author(s):  
Ali Ismet Kanli ◽  
Boriszlav Neducza
Keyword(s):  
Field Study ◽  
Near Surface ◽  
Electromagnetic Data ◽  
North East ◽  
The North ◽  
Surface Survey ◽  
Susceptibility Maps ◽  
Electromagnetic Measurements ◽  
Two Stages ◽  
Depth Ranges

<p>We carried out electromagnetic measurements in the vicinity of the near surface molybdenum contamination observed in the “Blue Lagoon” plum located in the north-east of Hungary. The aim of the investigation was to find the origin of the molybdenum pollution, situated in the area, which could be a container or other infrastructure leading to the source of contamination. The field study was conducted in two stages. In the first phase, we gathered electromagnetic data by using GEM-2 type equipment. We derived conductivity and susceptibility maps for each acquired frequency from the electromagnetic data. In the second stage of the field study, GPR data were obtained from 50 MHZ and 450 MHz antennas. In the GPR measurements, we gathered detailed information from GPR depth slices from very shallow depth ranges to deeper parts of the investigated area (from 50cm to 8 m depths). In all results from the measurements executed by the GEM-2 and (50 MHZ and 450 MHz) GPR equipment, there are several clear anomalies are observed in the data for the distribution of molybdenum contamination. Although there are several contaminated zones observed, no clear evidence of the source of contamination was found in the vicinity of the molybdenum pollution peak. </p><p> </p><p> </p><p><strong>Medicione</strong>s<strong> Electromagnéticas para Rastrear la Contaminación de Molibdeno en un Estudio de Superficies</strong></p><p><strong><br /></strong></p><p><strong>Resumen</strong></p>En este estudio se llevaron a cabo mediciones electromagnéticas en las inmediaciones de un foco de contaminación de molibdeno hallado en el "Blue Lagoon", al noreste de Hungría. El propósito de la investigación fue encontrar el origen de la contaminación de molibdeno, detectada en el área, y que podría ser el contenedor u otra infraestructura que lleve a la fuente de polución. El trabajo de campo se llevó a cabo en dos partes. En la primera fase se reunió la información electromagnética a través del equipo GEM-2. De esta forma se obtuvieron mapas de conductividad y susceptibilidad para cada frecuencia adquirida de la información electromagnética. En la segunda fase del estudio de campo se obtuvieron datos del radar de penetración terrestre (GPR, en inglés) con antenas de 50 y de 450 megahercios (MHZ). En las mediciones GPR se recopiló información detallada de las muestras de penetración en un rango desde la superficie a la profundidad en el área de estudio (desde 50 cm a 8 m de profundidad). En todos los resultados de las medidas hechas con los equipos GEM-2 y GPR se encontraron varias anomalías en la distribución de datos de la contaminación por molibdeno. A pesar de que se observaron varias zonas contaminadas, no hay evidencia clara de la fuente de polución encontrada alrededor del pico de contaminación por molibdeno.</p>

Comparison of remote sensing-based indices for ash vitality detection in North-East Germany

2020 ◽  
Author(s):  
Michael Förster ◽  
Anne Clasen ◽  
Kai Jütte ◽  
Veronika Döpper ◽  
Birgit Kleinschmit
Keyword(s):  
Remote Sensing ◽  
East Germany ◽  
Remote Sensing Data ◽  
North East ◽  
The North ◽  
Ash Trees ◽  
One Year ◽  
Regional Forest ◽  
Structural Indices ◽  
Higher Sensitivity

&lt;p&gt;The north-East of Europe is affected by the ash (Fraxinus excelsior) dieback caused by the fungal pathogen Hymenoscyphus pseudoalbidus. A great variety of studies utilize remote sensing data and subsequently derived spectral indices to estimate the magnitude and spatial distribution of the damage for different tree types.&amp;#160;&lt;/p&gt;&lt;p&gt;Often, structural indices, such as the NDVI are applied to detect already affected tree (sometimes even for early detection). However, there are differences in the suitability of an index. While a structural index, might have advantages when the canopy is not closed, pigment-based indices can show more variation within a full crown coverage forest. Therefore, the season of data acquisition might define the preferred index-selection. The same accounts not just for seasonal but for inter-annual changes, too. Here, the pigment indices show a higher sensitivity towards changes due to damages than structural indices.&lt;/p&gt;&lt;p&gt;To show these differences, the presented study is evaluating a variety of indices derived by hyperspectral imagery for affected ash trees in north-east Germany. This includes images from different phenological stages within one year (2015) and a comparison between 2011, 2015, and 2019 because the decline increased severely within this timespan for the observed trees. The indices were compared with tree damage estimations from the regional forest administration.&amp;#160;&lt;/p&gt;&lt;p&gt;Preliminary results show a better relation for structural indices in autumn, but higher relation for pigment-based indices in spring and summer, once the crown is closed. A higher sensitivity to changes between 2011 and 2019 can be shown for pigment-based indices.&lt;/p&gt;

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