18 research outputs found
The improved algorithm of automatic detection and location of earthquakes by a single seismic array and its application for study of aftershock sequence in the spitsbergen archipelago
No full textО регистрации схода снежных лавин геофизическими методами в Хибинском массиве
No full textIn 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.В зимние месяцы 2018–2020 гг. Кольский филиал Единой геофизической службы РАН проводил эксперименты по совместной регистрации сходов снежных лавин в Хибинском горном массиве с помощью сейсмических и инфразвуковых датчиков во время работ по принудительному спуску снежной массы. Цель экспериментов – оценка возможности регистрации схода снежных лавин геофизическими методами. Актуальность развития методов дистанционной регистрации фактов схода снежных лавин обусловлена отсутствием представительной статистики о частоте и закономерностях возникновения данного опасного природного явления. Сложность регистрации снежных лавин связана с их сходом зачастую в труднодоступных районах и в условиях плохой видимости. Для регистрации сигналов, генерируемых сходом лавин, применялись различные конфигурации инфразвуковых групп, состоящих из трех разнесенных в пространстве датчиков (микрофонов MPA 201 или микробарографов Hyperion IFS-4000), а также портативная сейсмическая станция Guralp CMG-6TD. В результате экспериментов получены записи инфразвуковых сигналов на различных удалениях от лавинного очага. Данные записи обработаны при помощи автоматического детектора, реализующего амплитудные и кросс-корреляционные методы обнаружения сигналов. Проанализированы спектральный состав записей и их характерный вид. Отличительными чертами сигналов, вызванных сходом лавин, являются большая длительность и изменение азимута на источник. Доминирующие частоты сигнала лежат в области 1–10 Гц. Сделаны выводы о недостаточной чувствительности сейсмического метода при размещении сейсмометра на удалении первых километров от лавинного очага, а также о высокой применимости инфразвукового метода для регистрации фактов схода лавин. Полученные результаты позволят разработать методику автоматического детектирования сигналов, генерируемых лавинами, по данным инфразвуковой регистрации, необходимую для построения системы непрерывного мониторинга лавинной активности.PublishedReferee
The European Arctic Seismic Bulletin for the years 1990 – 2013
No full textRecent years have shown an increased interest in Polar research and in particular in understanding tectonics and seismic hazard in the Arctic. To understand the seismic activity in the European Arctic, the seismic bulletins should be as complete as possible. We present a new seismic event bulletin for the European Arctic (70° – 90° N, -15° – 75° E), for the 24-year long period 1990 – 2013. The poster will show in detail the merging of the different sources taken in account for the compilation, the homogenization of the data and the relocation of the seismic events. With respect to the ISC bulletin for this region, the new bulletin contains 5,932 new seismic events and 54,630 new seismic onset readings from stations mostly located at regional distances. The gains are distributed over the entire study region, with the most significant contributions across the Svalbard Archipelago, along the Knipovich and northern Mohns Ridges, as well as northern Fennoscandia.Norwegian Research Council Grant 233973/H30Russian Foundation for Basic Research Grant 14-05-93080Russian Foundation for Basic Research Grant 18-05-70018https://doi.org/10.31905/TYLLQY8Tposte
Identification of iceberg-forming ice quakes from seismic and infrasound data
Get PDFThe application of a joint method of recording seismic and infrasound signals generated during ice calving from the terminal part of the outlet glaciers to identify the process of iceberg formation is considered. For many years, the Kola Branch of the Geophysical Service of the Russian Academy of Sciences has been developing technology for remote monitoring of the processes of destruction of ice sheets in the Arctic. To improve the methodology of geophysical monitoring of processes of the iceberg calving in the Arctic seas in the Svalbard archipelago, the experiment was conducted for the first time on the complex recording of the destruction of the Nordenskiold glacier using seismometers, infrasound microphones and video cameras. The aim of the experiment was to obtain time-synchronized recordings of seismic, infrasound and video signals produced by calving of the glacier edge. The synchronized recordings obtained as a result of the experiment were used to identify specific attributes that characterize the recordings of iceberg-inducing ice quakes. Results of the experiment showed that the calving events that produce floating icebergs generate seismic and infrasonic signals of a special spectral composition and are characterized by the presence of pronounced bands in the spectral-time representation. The revealed characteristic is a distinguishing evidence of a calving event with the iceberg-inducing potential from other types of ice quakes, such as cracking and movement of the glacier body. The experimental results obtained may be used for development of a system for seismic-infrasound monitoring of processes of the iceberg formation
The instrumental seismicity of the Barents and Kara sea region: relocated event catalog from early twentieth century to 1989
No full textSeismological observations of glaciers dynamic on the Spitsbergen archipelago
No full textThe paper provides a brief description of results of Spitsbergen glacier observations by the seismic method. The study has been carried out both by permanent and temporary stations data. Characteristic features of glacier-related seismic events have been shown. Main areas of glacier seismic activity on the Archipelago have been revealed. A detailed study of Horsund-fjord glacier activity has been carried out using local seismic station HSPB data. Temporal and spatial distributions of glacier-related events have been obtained for the area. Season variations in temporal distribution of the events have been foun
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Ground Truth Collections for Explosions in Northern Fennoscandia and Russia
No full textThis project is providing ground-truth information on explosions conducted at the principal mines within 500 kilometers of the ARCES station, and is assembling a seismic waveform database for these events from local and regional stations. The principal mines of interest are in northwest Russia (Khibiny Massif, Olenogorsk, Zapolyamy, and Kovdor groups) and Sweden (Malmberget, Kiruna). These mines form a natural laboratory for examining the variation of mining explosion observations with source type, since they include colocated surface and underground mines and mines conducting a variety of different shot types. In September 2002 we deployed two lines of temporary stations from the Khibiny Massif through and to the north of the ARCES station. This deployment is producing data that will allow researchers to examine the variation of discriminants caused by varying source-receiver distance and the diversity of explosion types. To date, we have collected ground-truth information on 1,118 explosions in the Kola Peninsula, and have assembled waveform data for approximately 700 of these. The database includes waveforms from instruments temporarily deployed in the Khibiny Massif mines, from the Apatity network just outside of the Massif, from LVZ, KEV and ARCES, and from the stations deployed along the two lines into northern Norway. In this paper we present representative waveforms for several types of shots recorded at various regional distances. We have conducted a preliminary study of the variation of phase ratios as a function of source type. This study shows significant differences in Pd/Sn and Pd/Lg ratios for two types of mining explosions: surface ripple-fired explosions and compact underground explosions. Compact explosions are, typically, underground explosions of a few tons with only one or two short delays, and are the closest approximation to single, well-tamped explosions available in the Khibiny mines. The surface shots typically are much larger (ranging up to hundreds of tons), with many delays. The surface mine that we present results for typically also conducts several distinct shots across the mine nearly simultaneously (with a few seconds or tens of seconds). Measured phase ratios are more consistent for compact underground explosions. This consistency is an expected result given the smaller scope for shot variation in these smaller events. In addition, Pd/Lg ratios appear more stable than Pd/Sn ratios for both types of events. The most interesting result is that the compact underground explosions are richer in shear energy (i.e. having smaller P/S ratios) than their surface ripple-fired counterparts. We continue to work on an approach for identifying the principal mines to be targeted for screening at a particular station. Often, routine industrial blasts constitute a large proportion of events detected by monitoring stations close to major mining districts. Many mines may be present, and it may be a problem to determine which subset of mines is responsible for the majority of the events, and should be prime candidates for the deployment of ground-truth collection resources. Our solution to this problem entails several steps. The first is to find geographic clusters of events that may correspond to major groups of mines. For this step, we use event density maps generated from existing network catalogs. This year we examined some of the tradeoffs in generating event density maps: use of automated bulletins to produce maps vs. analyst-reviewed bulletins, and the amount of time required to produce stables maps which can be used to identify significant mines
