scholarly journals Registration of avalanches in the Khibiny Mountains by the geophysical methods

Vestnik MGTU ◽  
2021 ◽  
Vol 24 (1) ◽  
pp. 69-79
Author(s):  
I. S. Fedorov ◽  
A. V. Fedorov ◽  
V. E. Asming
Keyword(s):  
Seismic Station ◽  
Geophysical Methods ◽  
Spectral Composition ◽  
Detection Methods ◽  
Mountain Range ◽  
Characteristic Appearance ◽  
Long Duration ◽  
Detection Of Signals ◽  
Dominant Frequencies ◽  
Snow Mass

In the winter months of 2018-2020 the Kola Branch of the Unified Geophysical Service RAS conducted experiments on the joint registration of avalanches in the Khibiny mountain range using seismic and infrasonic sensors during work on the forced descent of the snow mass. The aim of the experiments is to assess the possibility of avalanche detection using the geophysical methods. The lack of representative statistics on the frequency and regularity of avalanches is the reason for the relevance of developing methods of their remote registration. The difficulty of registering avalanches is due to their occurrence often in hard-to-reach areas and in poor visibility conditions. To record signals generated by avalanches, different configurations of infrasound panels consisting of three spatially separated sensors (MPA 201 or Hyperion IFS-4000 microbarographs) and a portable seismic station Guralp CMG-6TD were used. As a result of the experiments, infrasound recordings were obtained at different distances from the avalanche source. The infrasound group recordings collected from the experiments were processed using an automatic detector implementing amplitude and cross-correlation signal detection methods. The spectral composition of the recordings and their characteristic appearance were analyzed. Avalanche-induced signals are characterized by long duration and changes in azimuth to the source. The dominant frequencies of the signal lie in the region of 1-10 Hz. Conclusions are made about the insufficient sensitivity of the seismic method when the seismometer is located at a distance of the first kilometers from the avalanche source, as well as the high applicability of the infrasound method for recording the facts of avalanches. The results obtained will make it possible to develop a methodology for automatic detection of signals generated by avalanches using the data of infrasound registration. This is the necessary basis for building a system for continuous monitoring of avalanche activity.

Microseismicity in the Eastern Alps: Preliminary Results From the Swath-D Network

2021 ◽  
Author(s):  
Rens Hofman ◽  
Joern Kummerow ◽  
Simone Cesca ◽  
Joachim Wassermann ◽  
Thomas Plenefisch ◽  
...  
Keyword(s):  
Large Data ◽  
Eastern Alps ◽  
Detection Methods ◽  
Mountain Range ◽  
Network Methods ◽  
Data Volume ◽  
Geophysical Processes ◽  
The Alps ◽  
Mountain Belts ◽  
Surrounding Areas

<p>The AlpArray seismological experiment is an international and interdisciplinary project to advance our understanding of geophysical processes in the greater Alpine region. The heart of the project consists of a large seismological array that covers the mountain range and its surrounding areas. To understand how the Alps and their neighbouring mountain belts evolved through time, we can only study its current structure and processes. The Eastern Alps are of prime interest since they currently demonstrate the highest crustal deformation rates. A key question is how these surface processes are linked to deeper structures. The Swath-D network is an array of temporary seismological stations complementary to the AlpArray network located in the Eastern Alps. This creates a unique opportunity to investigate high resolution seismicity on a local scale.</p><p>In this study, a combination of waveform-based detection methods was used to find small earthquakes in the large data volume of the Swath-D network. Methods were developed to locate the seismic events using semi-automatic picks, and estimate event magnitudes. We present an overview of the methods and workflow, as well as a preliminary overview of the seismicity in the Eastern Alps.</p>

Synoptic Analysis of Extreme Hourly Precipitation in Taiwan during 2003–12

2017 ◽  
Vol 145 (12) ◽  
pp. 5123-5140 ◽  
Author(s):  
Mengwen Wu ◽  
Chun-Chieh Wu ◽  
Tzu-Hsiung Yen ◽  
Yali Luo
Keyword(s):  
Spatial Distribution ◽  
Statistical Characteristics ◽  
Mountain Range ◽  
Hourly Precipitation ◽  
Long Duration ◽  
Evolution Pattern ◽  
Short Period ◽  
Hourly Rainfall ◽  
Synoptic Forcing ◽  
Precipitation Records

This study investigates the statistical characteristics of extreme hourly precipitation over Taiwan during 2003–12 that exceeds the 5-, 10-, and 20-yr return values and 100 mm h−1. All the extreme precipitation records are classified into four types according to the synoptic situations under which they occur: tropical cyclones (TCs), fronts, weak-synoptic forcing, and vortex/shear line types. The TC type accounts for over three-quarters of the total records, while the front type and weak-synoptic forcing type are comparable (9%–13%). Extreme hourly precipitation is mostly caused by mei-yu fronts during May–mid-June and by TCs during July–October. The TC type tends to have a long duration time (>12 h) with a symmetrical evolution of hourly rainfall intensity, while the front type and weak-synoptic forcing type mainly occur over a short period (<6 h) with a slightly asymmetrical evolution pattern. The TC type is further divided into seven subtypes according to the location of the TC center relative to the island. When the TC center is over the island or near the coastline (distance <100 km), the spatial distribution of subtypes I–IV is largely determined by the interaction between the TC circulation and topography when a TC center is over the northwest, south, east, or northeast portion of Taiwan, respectively. When the TC center is far away (distance >100 km) from the island, the strength of the environmental southwesterly or northeasterly winds and the impingement of TC circulation on the east side of the Central Mountain Range are also key factors determining the spatial distribution of subtypes V–VII.

scholarly journals Signal periodicity detection using Ramanujan subspace projection

2020 ◽  
Vol 71 (5) ◽  
pp. 326-332
Author(s):  
Deepa Abraham ◽  
Manju Manuel
Keyword(s):  
Signal Processing ◽  
Detection Methods ◽  
Subspace Projection ◽  
Speech Signal Processing ◽  
Periodicity Detection ◽  
Periodic Decomposition ◽  
Signal Period ◽  
Ramanujan Sums ◽  
Pitch Analysis ◽  
Detection Of Signals

Abstract Signal periodic decomposition and periodic estimation are two crucial problems in the signal processing domain. Due to its significance, the applications have been extended to fields like periodic sequence analysis of biomolecules, stock market predictions, speech signal processing, and musical pitch analysis. The recently proposed Ramanujan sums (RS) based transforms are very useful in analysing the periodicity of signals. This paper proposes a method for periodicity detection of signals with multiple periods based on autocorrelation and Ramanujan subspace projection with low computational complexity. The proposed method is compared with other signal periodicity detection methods and the results show that the proposed method detects the signal period correctly in less time.

scholarly journals Determining geophysical responses from burials in graveyards and cemeteries

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. B245-B255 ◽  
Author(s):  
Henry C. Dick ◽  
Jamie K. Pringle ◽  
Kristopher D. Wisniewski ◽  
Jon Goodwin ◽  
Robert van der Putten ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Target Detection ◽  
High Frequency ◽  
Geophysical Methods ◽  
Low Frequency ◽  
Coarse Sand ◽  
Detection Methods ◽  
Surface Data ◽  
Ground Penetrating

Graveyards and cemeteries around the world are increasingly designated as full. Therefore, there is a requirement to identify vacant spaces for new burials or to identify existing ones to exhume and then reinter if necessary. Geophysical methods offer a potentially noninvasive target detection solution; however, there has been limited research to identify optimal geophysical detection methods against burial age. We have collected multifrequency (225–900 MHz) ground-penetrating radar (GPR), electrical resistivity, and magnetic susceptibility surface data over known graves with different burial ages and soil types in three UK church graveyards. Results indicate that progressively older burials are more difficult to detect, but this decrease is not linear and is site specific. Medium- to high-frequency GPR and magnetic susceptibility was optimal in clay-rich soils, medium- to high-frequency GPR and electrical resistivity in sandy soils, and electrical resistivity and low-frequency GPR in coarse sand and pebbly soils, respectively. A multigeophysical technique approach should be used by survey practitioners where grave locations are not known to maximize target detection success. Grave soil and grave cuts are important grave position indicators. Grave headstones were not always located where burials were located. We have determined the value of these techniques in grave detection and could potentially date burials from their geophysical responses.

scholarly journals Human Vital Signs Detection Methods and Potential Using Radars: A Review

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1454 ◽  
Author(s):  
Mamady Kebe ◽  
Rida Gadhafi ◽  
Baker Mohammad ◽  
Mihai Sanduleanu ◽  
Hani Saleh ◽  
...  
Keyword(s):  
Detection System ◽  
Skin Irritation ◽  
Vital Signs ◽  
The Elderly ◽  
Detection Methods ◽  
Distinct Advantage ◽  
Monitoring Methods ◽  
Vital Signs Monitoring ◽  
Long Duration ◽  
Measurement Results

Continuous monitoring of vital signs, such as respiration and heartbeat, plays a crucial role in early detection and even prediction of conditions that may affect the wellbeing of the patient. Sensing vital signs can be categorized into: contact-based techniques and contactless based techniques. Conventional clinical methods of detecting these vital signs require the use of contact sensors, which may not be practical for long duration monitoring and less convenient for repeatable measurements. On the other hand, wireless vital signs detection using radars has the distinct advantage of not requiring the attachment of electrodes to the subject’s body and hence not constraining the movement of the person and eliminating the possibility of skin irritation. In addition, it removes the need for wires and limitation of access to patients, especially for children and the elderly. This paper presents a thorough review on the traditional methods of monitoring cardio-pulmonary rates as well as the potential of replacing these systems with radar-based techniques. The paper also highlights the challenges that radar-based vital signs monitoring methods need to overcome to gain acceptance in the healthcare field. A proof-of-concept of a radar-based vital sign detection system is presented together with promising measurement results.

An Audiospectrographic Study of Male Stridulation in the Genus Corixa Geoffr. (Hemiptera, Corixidae)

1981 ◽  
Vol 36 (1-2) ◽  
pp. 189-191 ◽  
Author(s):  
Christine Finke ◽  
Joachim Prager
Keyword(s):  
Frequency Spectrum ◽  
Spectral Composition ◽  
Frequency Responses ◽  
Threshold Frequency ◽  
Tympanic Organ ◽  
Dominant Frequencies

Abstract The stridulation signals of three species of the Genus Corixa were investigated especially with respect to their spectral composition. Thee dominant frequencies are: 2.7 kHz for C. panzeri, 2.2 kHz for C. dentipes and 2.0 kHz for C. punctata. For C. punctata the threshold frequency responses, especially for one (A1) of both receptor units of the mesothoracic tympanic organ, correspond well to the frequency spectrum of the emitted sounds.

scholarly journals Unusual seismic signals associated with the activity at Galeras volcano, Colombia, from July 1992 to September 1994

1996 ◽  
Vol 39 (2) ◽  
Author(s):  
R. A. Torres C. ◽  
D. M. Gómez M. ◽  
L. Narvàez M.
Keyword(s):  
Gas Phase ◽  
Lava Dome ◽  
Solid Material ◽  
Seismic Signals ◽  
Free Gas ◽  
Source Characteristics ◽  
Cooling Crystallization ◽  
Impedance Contrast ◽  
Long Duration ◽  
Dominant Frequencies

After the emplacement of a lava dome at Galeras volcano in 1991, seven eruptions occurred from July 16, 1992, to September 23, 1994, six of which were preceded by quasi-monochromatic, long-duration seismic events with slowly decaying coda named «tornillos» (screws). The dominant frequencies of these unusual seismic signals are related to source characteristics and show temporal changes, diminishing and then tending to stabilize before an eruption. At the same time, the accumulated number and the duration of these signals increase several days prior to the eruption. The increase in the duration of the tornillo events and the decline of the dominant frequencies both suggest an increasing impedance contrast between the surrounding solid material and the fluid. These characteristics may be associated with an increase in the free gas phase in the magma produced by saturation of volatiles due to cooling, crystallization and partial solidification of the column of magma plugging the conduits. The solidified magma can contribute to sealing the conduits and preventing free gas escape, with consequent generation of overpressure. An eruption is initiated when the overpressure exceeds the resistance strength of the solid material.

Methodological bases of complex geomechanical studies for selecting optimal parameters of drainage of waterlogged areas fields

2020 ◽  
pp. 127-137
Author(s):  
V. V. Melnik ◽  
T. F. Harisov ◽  
A. L. Zamyatin
Keyword(s):  
High Efficiency ◽  
Geophysical Methods ◽  
Drainage System ◽  
Rocky Mountain ◽  
Integrated Approach ◽  
Mountain Range ◽  
Water Conductivity ◽  
Tectonic Disturbances ◽  
Water Cut ◽  
The Cost

This article provides examples of an integrated approach to the study of the geomechanical features of mineral deposits responsible for the filtration properties of a massif and, as a result, increased water cut of the field as a whole. Having knowledge of a number of characteristics that affect the water conductivity of the massif, it seems possible to select the parameters of the drainage system of the field in such a way as to minimize the cost of creating an intake due to the point arrangement of water-reducing wells. Structural-tectonic disturbances with geodynamic mobility, due to which aquifers and caverns in karst rocks remain open and are not filled with clay and sand materials, are the main search features of aquifers. The boundaries of the zones of structural-tectonic disturbances and their spread are well detected by ground-based geophysical methods, such as electrical exploration (boundaries of disturbances) and spectral seismic profiling (depth of propagation of zones of increased fracturing). It is proposed to use satellite geodesy as the most effective way to determine coordinates at large bases as geodetic methods for studying modern geodynamic activity. The examples of dewatering the fields using the proposed approach have shown their high efficiency at minimal cost for the creation of water intake facilities. This technique allows you to get the greatest effect under the conditions of aquifers confined to the rocky mountain range, especially in conditions of karst propagation.

scholarly journals Geophysical researches in mine

2020 ◽  
Vol 7 (7) ◽  
pp. 49-55
Author(s):  
Timur F. Kharisov ◽  
◽  
Vitalii V. Melnik ◽  
Aleksei L. Zamiatin ◽  
◽  
...  
Keyword(s):  
Rock Mass ◽  
Geophysical Methods ◽  
Spectral Composition ◽  
Oil Industry ◽  
Structural Heterogeneity ◽  
Seismic Profile ◽  
Measurement Methods ◽  
Oscillatory Process ◽  
Electrophysical Properties ◽  
Exploration Drilling

Introduction. Geophysical methods of rock mass research are among the most effective ways of solving various mining problems being widely used in mining, gas and oil industry, as well as in science. They allow to conduct prospecting and prospect evaluation remotely, to reveal structural heterogeneity, cavities, zones of contacts of various environments in the rock mass with rather high precision. The article contains an example of solution to the problem of finding a fallen and spread through three-tier shelf in an operated shaft. Research methodology. Spectral seismic profile (SSP) method and GPR were used for prospecting. SSP is based on the dependence between the spectral composition of the oscillatory process occurring when rock mass exposed surface undergoes impact effect, and the structure of the rock mass. GPR method is based on the reflection of the electromagnetic wave from boundaries between media with different electrophysical properties. Research results. Geophysical methods have made it possible to identify the following boundaries of the metal shelf filled with rock mass inside the vertical shaft: 5.5–6.0 m, 10.5–11.0 m, 15 m. Combined results of the two measurement methods and their comparative analysis show rather high convergence therefore confirming the reliability of the obtained results. Exploration drilling of downholes from the level working confirmed the obtained results.

scholarly journals Ultrasonic signalling by a Bornean frog

2007 ◽  
Vol 4 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Victoria S Arch ◽  
T. Ulmar Grafe ◽  
Peter M Narins
Keyword(s):  
High Frequency ◽  
Spectral Composition ◽  
Acoustic Energy ◽  
Ultrasonic Signals ◽  
Hearing Sensitivity ◽  
Wide Range ◽  
Lower Vertebrates ◽  
Modulation Pattern ◽  
Insight Into ◽  
Dominant Frequencies

Among anuran amphibians, only two species, Odorrana tormota and Huia cavitympanum , are known to possess recessed tympanic membranes. Odorrana tormota is the first non-mammalian vertebrate demonstrated to communicate with ultrasonic frequencies (above 20 kHz), and the frogs' sunken tympana are hypothesized to play a key role in their high-frequency hearing sensitivity. Here we present the first data on the vocalizations of H. cavitympanum . We found that this species emits extraordinarily high-frequency calls, a portion of which are comprised entirely of ultrasound. This represents the first documentation of an anuran species producing purely ultrasonic signals. In addition, the vocal repertoire of H. cavitympanum is highly variable in frequency modulation pattern and spectral composition. The frogs' use of vocal signals with a wide range of dominant frequencies may be a strategy to maximize acoustic energy transmission to both nearby and distant receivers. The convergence of these species' call characteristics should stimulate additional, phylogenetically based studies of other lower vertebrates to provide new insight into the mechanistic and evolutionary foundations of high-frequency hearing in all vertebrate forms.

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