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>

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 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 High resolution reflection seismic profiling over the Tjellefonna fault in the Møre-Trøndelag Fault Complex, Norway

2012 ◽  
Vol 4 (1) ◽  
pp. 241-278 ◽  
Author(s):  
E. Lundberg ◽  
C. Juhlin ◽  
A. Nasuti
Keyword(s):  
P Wave ◽  
The South ◽  
Seismic Profiles ◽  
Surface Geometry ◽  
Secondary Fracture ◽  
Near Surface ◽  
North West ◽  
Reflection Seismic ◽  
North East ◽  
The North

Abstract. The Møre-Trøndelag Fault Complex (MTFC) is one of the most prominent fault zones of Norway, both onshore and offshore. In spite of its importance, very little is known of the deeper structure of the individual fault segments comprising the fault complex. Most seismic lines have been recorded offshore or focused on deeper structures. This paper presents results from two reflection seismic profiles, located on each side of the Tingvollfjord, acquired over the Tjellefonna fault in the south-eastern part of the MTFC. Possible kilometer scale vertical offsets reflecting, large scale north-west dipping normal faulting separating the high topography to the south-east from lower topography to the north-west have been proposed for the Tjellefonna fault. In this study, however, the Tjellefonna fault is interpreted to dip approximately 50–60° towards the south-east to depths of at least 1.4 km. Travel-time modeling of reflections associated with the fault was used to establish the geometry of the fault structure at depth and detailed analysis of first P-wave arrivals in shot-gathers together with resistivity profiles were used to define the near surface geometry of the fault zone. A continuation of the structure on the north-eastern side of the Tingvollfjord is suggested by correlation of an in strike direction P-S converted reflection (generated by a fracture zone) seen on the reflection data from that side of the Tingvollfjord. The reflection seismic data correlate well with resistivity profiles and recently published near surface geophysical data. A highly reflective package forming a gentle antiform structure was also identified on both seismic profiles. The structure may be an important boundary within the gneissic basement rocks of the Western Gneiss Region. The Fold Hinge Line is parallel with the Tjellefonna fault trace while the topographic lineament diverges, following secondary fracture zones towards north-east.

scholarly journals MUYAKAN-II EARTHQUAKE on MAY 23, 2014 with КР=14.3, Mw=5.5, I0=7–8 (Northern Baikal region)

2020 ◽  
pp. 323-333
Author(s):  
N. Gileva ◽  
V. Melnikova ◽  
A. Seredkina ◽  
Ya. Radziminovich
Keyword(s):  
Seismic Moment ◽  
Main Shock ◽  
Moment Tensor ◽  
Seismic Hazard Assessment ◽  
Baikal Rift Zone ◽  
Temporal Analysis ◽  
Seismic Moment Tensor ◽  
Depth Range ◽  
North East ◽  
The North

We consider the May 23, 2014 Muyakan earthquake (Mw=5.5) occurred in the Muyakan Range at the north-east of the Baikal rift zone near the eastern tunnel portal of the Baikal-Amur Mainline. This event was followed by numerous aftershocks (КР=5.6–9.9) which number exceeded 2000 by the end of the year. Spatio-temporal analysis of the Muyakan seismic sequence shows that its epicentral field consists of two isolated clusters: eastern and western ones. All the main events including the foreshocks, main shock and the strongest aftershocks (Mw=4.4; 4.5) occurred in the eastern cluster while only small seismic events (КР<10.0) were recorded in the western one. Seismic moment tensor was calculated for the Muyakan earthquake from surface wave amplitude spectra. As a result, we obtained information about the rift type focal mechanism, scalar seismic moment (M0=1.9•1017 Nm), moment magnitude (Mw=5.5) and hypocentral depth (h=24 km). From regional data, hypocentral depths of the main shock and the major number of the following earthquakes (80 %) were distributed in the depth range h=3–11 km. Maximum intensity of the main shock (4–5 according to MSK-64) was felt in Severomuysk urban village (=29 km). The obtained results could be used for seismic hazard assessment of the crucial part of the Baikal-Amur Mainline.

scholarly journals High-resolution (1 km) Polar WRF output for 79° N Glacier and the Northeast of Greenland from 2014–2018

2019 ◽  
Author(s):  
Jenny V. Turton ◽  
Thomas Mölg ◽  
Emily Collier
Keyword(s):  
High Resolution ◽  
Future Change ◽  
Near Surface ◽  
Northeast Region ◽  
Atmospheric Processes ◽  
North East ◽  
The North ◽  
Modelling Studies ◽  
Research Questions ◽  
Enhanced Surface

Abstract. The northeast region of Greenland is of growing interest due to changes taking place on the large marine-terminating glaciers which drain the north east Greenland ice stream. Nioghalvfjerdsfjordern, or 79° N glacier, is one of these glaciers that is currently experiencing accelerated thinning, retreat and enhanced surface melt. Understanding both the influence of atmospheric processes on the glacier and the interactions between the atmosphere and the changing surface is crucial for our understanding of present stability and future change. However, relatively few studies have focused on the atmospheric processes in this region, and even fewer have used high-resolution modelling as a tool for these research questions. Here we present a high-resolution (1 km) atmospheric modelling dataset, NEGIS_WRF, for the 79° N and northeast Greenland region from 2014–2018, and an evaluation of the model’s success at representing daily near-surface meteorology compared with two automatic weather station records. The dataset, (Turton et al, 2019b: https://doi.org/10.17605/OSF.IO/53E6Z), is now available for a wide variety of applications ranging from atmospheric dynamics, to input for hydrological and oceanic modelling studies.

Orientations of Broadband Stations of the KOERI Seismic Network (Turkey) from Two Independent Methods: P- and Rayleigh-Wave Polarization

2021 ◽  
Author(s):  
Pınar Büyükakpınar ◽  
Mustafa Aktar ◽  
Gesa Maria Petersen ◽  
Ayşegül Köseoğlu
Keyword(s):  
Receiver Function ◽  
Function Analysis ◽  
Eastern Mediterranean ◽  
Moment Tensor ◽  
Eastern Mediterranean Region ◽  
P Waves ◽  
Data Set ◽  
The North ◽  
Correct Orientation ◽  
Sensor Orientation

Abstract The correct orientation of seismic sensors is critical for studies such as full moment tensor inversion, receiver function analysis, and shear-wave splitting. Therefore, the orientation of horizontal components needs to be checked and verified systematically. This study relies on two different waveform-based approaches, to assess the sensor orientations of the broadband network of the Kandilli Observatory and Earthquake Research Institute (KOERI). The network is an important backbone for seismological research in the Eastern Mediterranean Region and provides a comprehensive seismic data set for the North Anatolian fault. In recent years, this region became a worldwide field laboratory for continental transform faults. A systematic survey of the sensor orientations of the entire network, as presented here, facilitates related seismic studies. We apply two independent orientation tests, based on the polarization of P waves and Rayleigh waves to 123 broadband seismic stations, covering a period of 15 yr (2004–2018). For 114 stations, we obtain stable results with both methods. Approximately, 80% of the results agree with each other within 10°. Both methods indicate that about 40% of the stations are misoriented by more than 10°. Among these, 20 stations are misoriented by more than 20°. We observe temporal changes of sensor orientation that coincide with maintenance work or instrument replacement. We provide time-dependent sensor misorientation correction values for the KOERI network in the supplemental material.

Near-surface captures of post-juvenile anglerfish in the North-east Atlantic-an unsolved mystery

2000 ◽  
Vol 57 (4) ◽  
pp. 1083-1087 ◽  
Author(s):  
J. R. G. Hislop ◽  
J. C. Holst ◽  
D. Skagen
Keyword(s):  
East Atlantic ◽  
Near Surface ◽  
North East ◽  
The North

A geophysical study on the Abu Gharadig basin, Egypt

Geophysics ◽  
1985 ◽  
Vol 50 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Ghareeb M. Awad
Keyword(s):  
Late Cretaceous ◽  
Sedimentary Cover ◽  
Gravity Anomalies ◽  
Western Desert ◽  
Basement Complex ◽  
Near Surface ◽  
North East ◽  
The North ◽  
Tectonic Disturbances ◽  
East West

The area of study comprises one of the most hydrocarbon‐potential basins of the Egyptian Western Desert, the Abu Gharadig basin. Major marine transgression and regression cycles dominated the territory during different geologic times. Those depositional cycles, together with at least three tectonic cycles—the end of the Paleozoic Hercynean, the close of the Jurassic until the Late Cretaceous and, the close of the Cretaceous until Mid‐Teritary—resulted in a highly deformed, thick sedimentary cover. A study of the geophysical anomalies of the basin, including those indicated by aeromagnetic, gravity, and seismic data as well as the study of about 60 deep wells drilled within and around the Abu Gharadig basin, has revealed that the major tectonic disturbances of the area were caused by basement complex block faulting. These major tectonic disturbances have produced great variations in the thickness and distribution of the various geologic units throughout the region. Aeromagnetic anomalies and the wells which reached the basement indicate great variations in the depths and type of the basement complex and the presence of major intrusions in the region. The major fracturing is indicated to be mainly along an east‐west, west‐northwest and east‐northeast directions. The Bouguer gravity anomalies indicate major basement fracturing as well as variations in sedimentary patterns, erosions, and subsequent tectonic disturbances. The most obvious anomalous trends on the gravity map, based on frequency and amplitude, are the north‐east to east‐northeast, the east‐west and the west‐northwest. The main Abu Gharadig depositional center does not show sharp variations because of the homogeneity of the near‐surface rocks and the great basement depth (20 000-40 000 ft). Seismic interpretation has confirmed the presence of all these fracturing trends. It also identified some major structural trends. These are closely related to the depositional centers, and represent potential drilling locations, especially those associated with Late Cretaceous‐Tertiary active contemporaneous faulting.

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