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Krzysztof P. Teisseyre 《Acta Geophysica》2011,59(1):5-28
Three seismic events in L’Aquila region and one in western Greece have been chosen for comparative analysis of two kinds of
seismic motions, spin and twist. These torque components of the seismic field were detected in horizontal plane with the rotational
seismometers. Homologous parts were sought in the signals of spin and twist components — curve of one component was compared
to the other directly and after transformations: phase-shifting and sign reversal. To achieve better clarity, these operations
were done on the data divided into several descendant signals with the use of band-pass filtration. Conformities of spin and
twist, revealed in this way, are assumed to be results of distant processes in the source, where relations between rotational
and shear motions include retardations. 相似文献
3.
Gennadiy V. Ryabinin Valeriy A. Gavrilov Yuriy S. Polyakov Serge F. Timashev 《Acta Geophysica》2012,60(3):874-893
We propose a new type of earthquake precursor based on the analysis of correlation dynamics between geophysical signals of
different nature. The precursor is found using a two-parameter cross-correlation function introduced within the framework
of flicker-noise spectroscopy, a general statistical physics approach to the analysis of time series. We consider an example
of cross-correlation analysis for water salinity time series, an integral characteristic of the chemical composition of groundwater,
and geoacoustic emissions recorded at the G-1 borehole on the Kamchatka peninsula in the time frame from 2001 to 2003, which
is characterized by a sequence of three groups of significant seismic events. We found that cross-correlation precursors took
place 27, 31, and 35 days ahead of the strongest earthquakes for each group of seismic events, respectively. At the same time,
precursory anomalies in the signals themselves were observed only in the geoacoustic emissions for one group of earthquakes. 相似文献
4.
V. N. Chebrov D. V. Droznin Yu. A. Kugaenko V. I. Levina S. L. Senyukov V. A. Sergeev Yu. V. Shevchenko V. V. Yashchuk 《Journal of Volcanology and Seismology》2013,7(1):16-36
This paper presents the main results from the development of the detailed seismological observation system in Kamchatka and the information on the system as of 2011. We describe the networks of seismological stations, the systems for the acquisition, storage, and processing of seismological observations and their technical, methodological, and software support. We discuss the basic characteristics of the recording channels and the system as a whole. We present the information resources of the Kamchatka seismological data bank that provide for basic research in earth sciences. In 2011, the system of seismological observation in Kamchatka was a specialized network for acquisition (recording), storage, transmission, and processing of seismic and geophysical data that provides support for the effective monitoring of seismic and volcanic activities, as well as tsunami warning. 相似文献
5.
Summary Systematic observations of natural seismic activity in the West-Bohemian earthquake-swarm region began at two autonomous seismological
stations of the Geophysical Institute, the digital station Novy Kostel (NKC) and the analogue station Skalná (SKC), in May
1986 and December 1989, respectively. This paper presents the station data of NKC and SKC, the method of processing the records,
and the database structure. It also includes the interpretation of observations made at these stations in the period 1986–1993.
It was found that the seismic activity in the West Bohemian region, in the Vogtland (Saxony) and NE Bavaria was continuous.
Between two strong earthquake swarms, the energy in this area was released in the form of a large number of micro-earthquakes
of a markedly swarm-like nature, mostly concentrated in six focal regions. 相似文献
6.
Seismic monitoring of industrial objects: Problems and solutions 总被引：1，自引：0，他引：1
Using the example of safety provision problems of hydraulic engineering structures (HESs), the seismic monitoring experience is analyzed (parameters of states of objects, equipment and schemes for fulfilling seismic observations) and, based on this, it is proposed to modify existing industrial monitoring practices. The efficiency of the different kinds of the HES monitoring performed by the united seismic equipment with an expanded dynamic range is shown. Innovative instrumental solutions for recording seismic signals are described. 相似文献
7.
A. L. Sobisevich K. Kh. Kanonidi L. E. Sobisevich D. G. Gridnev 《Seismic Instruments》2010,46(3):228-233
The results of experimental observations over variations of the Earth’s magnetic field recorded by the instruments of the
North Caucasus Geophysical Observatory are presented. We observed specific ultralow-frequency quasi-oscillatory waveforms
preceding strong distant seismic events in the structure of electromagnetic signals. 相似文献
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Vladimir Schenk Zdeňka Schenkova Zuzana Jechumtálová 《Studia Geophysica et Geodaetica》2009,53(3):329-341
In West Bohemia in the period of 2003–2005 five permanent GPS stations were established to detect local movement trends. Their
mutual position changes were determined from time series of GPS observations and were associated with seismic, gravity, and
geo-scientific data related to the geodynamics of the West Bohemian region. Knowledge of local physical processes based on
spatial and time earthquake occurrences, focal mechanisms of main events, stress and strain fields set up a tool for recent
seismotectonic analyses. The permanent GPS measurements bring independent effective phenomenon, direct monitoring of site
movements. The movements detected by our GPS stations evidenced WSW-ENE extension with subsiding trends in the western part
of the Cheb Basin and the Smrčiny Mts. Besides, there were monitored dextral movements along the Mariánské Lázně tectonic
fault zone (MLF). A comparison of results with previous data formed a presumption that an antithetic stress pattern has to
exist inside the inner part of the MLF tectonic zone. This antithetic stress can explain the coexistence of dextral and sinistral
movements on individual tectonic elements in the West Bohemian area. 相似文献
10.
A. Díaz-Moreno G. Barberi O. Cocina I. Koulakov L. Scarfì L. Zuccarello J. Prudencio A. García-Yeguas I. Álvarez L. García J. M. Ibáñez 《Surveys in Geophysics》2018,39(1):57-97
In the Central Mediterranean region, the production of chemically diverse volcanic products (e.g., those from Mt. Etna and the Aeolian Islands archipelago) testifies to the complexity of the tectonic and geodynamic setting. Despite the large number of studies that have focused on this area, the relationships among volcanism, tectonics, magma ascent, and geodynamic processes remain poorly understood. We present a tomographic inversion of P-wave velocity using active and passive sources. Seismic signals were recorded using both temporary on-land and ocean bottom seismometers and data from a permanent local seismic network consisting of 267 seismic stations. Active seismic signals were generated using air gun shots mounted on the Spanish Oceanographic Vessel ‘Sarmiento de Gamboa’. Passive seismic sources were obtained from 452 local earthquakes recorded over a 4-month period. In total, 184,797 active P-phase and 11,802 passive P-phase first arrivals were inverted to provide three different velocity models. Our results include the first crustal seismic active tomography for the northern Sicily area, including the Peloritan–southern Calabria region and both the Mt. Etna and Aeolian volcanic environments. The tomographic images provide a detailed and complete regional seismotectonic framework and highlight a spatially heterogeneous tectonic regime, which is consistent with and extends the findings of previous models. One of our most significant results was a tomographic map extending to 14 km depth showing a discontinuity striking roughly NW–SE, extending from the Gulf of Patti to the Ionian Sea, south-east of Capo Taormina, corresponding to the Aeolian–Tindari–Letojanni fault system, a regional deformation belt. Moreover, for the first time, we observed a high-velocity anomaly located in the south-eastern sector of the Mt. Etna region, offshore of the Timpe area, which is compatible with the plumbing system of an ancient shield volcano located offshore of Mt. Etna. 相似文献
11.
L. L. Khudzinsky 《Seismic Instruments》2011,47(1):93-95
The changes in the hardware/software system for seismic monitoring as applied to the conditions of the adit of the Institute
of Nuclear Research, Russian Academy of Sciences, in the Elbrus region are described. A three-component computer recording
within the frequency range of 10–120 Hz was carried out with the averaging of vibration amplitudes on an interval of 5 s.
The results of data processing for the first six months of monitoring carried out starting from March 2008 in the adit are
considered. The seismic field in the observation site has three main components: local earthquakes related to the two main
magmatic fluid sources located nearby; a slowly changing wave field, possibly related to the same sources; and technogenic
noise, in particular, vibration caused by the trolleys in motion, and a weak stationary background. 相似文献
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Results of magnetic observations in Yuzhno-Sakhalinsk during a strong earthquake and a local swarm of earthquakes, as well as magnetic signals recorded during propagation of seismic waves, are considered. The possibility of the identification of these signals in magnetograms is discussed. The results of this study are shown to be significant for the development of a prompt method for warning of the arrival of seismic waves. 相似文献
14.
Requirements for the seismic resistance of nuclear power plants (NPPs) considerably differ from those for of other industrial facilities due to the necessity of protecting not only the NPP itself, but also the environment from radiation hazard. According to special regulations, even if an NPP construction site is located in a region with low seismicity, the NPP design should be based on the maximum design earthquake and peak acceleration typical of the region. Note that seismic warning systems for NPPs differ fundamentally in design and operation principles from conventional seismic monitoring systems. Seismic warning systems are required to reliably detect seismic events threatening the operability of nuclear power plants, to promptly inform operators, and to prevent false alarms and unauthorized access to the system. Atomseismoizyskaniya LLC has developed a seismic warming system (SSZ-1M) and put it into trial operation at the reactor units of the Smolensk NPP in 2014–2015. The system comprises six seismic groups: two groups per each reactor unit. Each group consists of three independent seismic recording channels, the sensors of which are distributed around the reactor unit at a distance of up to 500 m from the latter. Each channel records three components of seismic signals; the acceleration vector is calculated and compared with a preset threshold. Signals exceeding the threshold are fed to a coincidence circuit that generates an alarm if two of the three signals exceed the threshold. This scheme excludes false alarms. The components of the system are characterized by high reliability and stability. The performance of the system channels has been officially certified. The system automatically performs continuous fault diagnosis. The programs responsible for system function and diagnostics are independent; the system units have individual equipment. To exclude the possibility of external impacts, the SSZ-1M warning system has no Internet connection. Special seismic signal simulators were developed to test the operability of the system when deployed. 相似文献
15.
L.S. Timiovska 《Soil Dynamics and Earthquake Engineering》1992,11(8):457-463
The attenuation of intensity of strong shaking is related to the dissipation of earthquake energy. It varies with distance from the epicenter, and depends on the local geological conditions. The 1437 data points have been collected from the Atlas of Isoseismal Maps (Catalogue of Earthquakes) in the UNDP/UNESCO Survey of the Seismicity of the Balkan Region (1974) and from unpublished data on seismic intensities in the Balkan region up to 1989.
A regression analysis has been performed to describe the attenuation of earthquake intensity in Macedonia in terms of epicentral intensity, I0, epicentral distance, R, and local geological conditions at the recording site, s (s = 0, 1 or 2 for soft, medium and hard geological site conditions). 相似文献
16.
The source parameters for 213 Bhuj aftershocks of moment magnitude varying from 2.16 to 5.74 have been estimated using the
spectral analysis of the SH- waveform on the transverse component of the three-componnet digital seismograms as well as accelerograms.
The estimated stress drop values for Bhuj aftershocks show more scatter (Mo0.5 to 1 ∞ Δσ) toward the larger seismic moment values (log Mo ≥ 1014.5 N-m, larger aftershocks), whereas, they show a more systematic nature (Mo3 ∞ Δσ) for smaller seismic moment (log Mo < 1014.5 N-m, smaller aftershocks) values. This size dependency of stress drop has also been seen from the relation between our estimated
seismic moment and source radius, however, this size-dependent stress drop is not observed for the source parameter estimates
for the other stable continental region earthquakes in India and around the world. The estimated seismic moment (Mo), source
radius (r) and stress drop (Δσ) for aftershocks of moment magnitude 2.16 to 5.74 range from 1.95 × 1012 to 4.5 × 1017 N-m, 239 to 2835 m and 0.63 to 20.7 MPa, respectively. The near-surface attenuation factor (k) is found to be large of the
order of 0.03 for the Kachchh region, suggesting thick low velocity sediments beneath the region. The estimated stress drop
values show an increasing trend with the depth indicating the base of seismogenic layer (as characterized by larger stress
drop values (>15 MPa)) lying in 22–26km depth range beneath the region. We suggest that the concentration of large stress
drop values at 10–36km depth may be related to the large stress/strain associvated with a brittle, competent intrusive body
of mafic nature. 相似文献
17.
I. Popova A. Rozhnoi M. Solovieva B. Levin V. Chebrov 《Izvestiya Physics of the Solid Earth》2016,52(2):305-317
In this paper, we suggest a technique for forecasting seismic events based on the very low and low frequency (VLF and LF) signals in the 10 to 50 Hz band using the neural network approach, specifically, the error back-propagation method (EBPM). In this method, the solution of the problem has two main stages: training and recognition (forecasting). The training set is constructed from the combined data, including the amplitudes and phases of the VLF/LF signals measured in the monitoring of the Kuril-Kamchatka region and the corresponding parameters of regional seismicity. Training the neural network establishes the internal relationship between the characteristic changes in the VLF/LF signals a few days before a seismic event and the corresponding level of seismicity. The trained neural network is then applied in a prognostic mode for automated detection of the anomalous changes in the signal which are associated with seismic activity exceeding the assumed threshold level. By the example of several time intervals in 2004, 2005, 2006, and 2007, we demonstrate the efficiency of the neural network approach in the short-term forecasting of earthquakes with magnitudes starting from M ≥ 5.5 from the nighttime variations in the amplitudes and phases of the LF signals on one radio path. We also discuss the results of the simultaneous analysis of the VLF/LF data measured on two partially overlapping paths aimed at revealing the correlations between the nighttime variations in the amplitude of the signal and seismic activity. 相似文献
18.
Maria C. Arango Fleur O. Strasser Julian J. Bommer Ruben Boroschek Diana Comte Hernando Tavera 《Journal of Seismology》2011,15(1):19-41
Earthquake hazard along the Peru–Chile subduction zone is amongst the highest in the world. The development of a database
of subduction-zone strong-motion recordings is, therefore, of great importance for ground-motion prediction in this region.
Accelerograms recorded by the different networks operators in Peru and Chile have been compiled and processed in a uniform
manner, and information on the source parameters of the causative earthquakes, fault-plane geometries and local site conditions
at the recording stations has been collected and reviewed to obtain high-quality metadata. The compiled database consists
of 98 triaxial ground-motion recordings from 15 subduction-type events with moment magnitudes ranging from 6.3 to 8.4, recorded
at 59 different sites in Peru and Chile, between 1966 and 2007. While the database presented in this study is not sufficient
for the derivation of a new predictive equation for ground motions from subduction events in the Peru–Chile region, it significantly
expands the global database of strong-motion data and associated metadata that can be used in the derivation of predictive
equations for subduction environments. Additionally, the compiled database will allow the assessment of existing predictive
models for subduction-type events in terms of their suitability for the Peru–Chile region, which directly influences seismic
hazard assessment in this region. 相似文献
19.
A. D. Kostyuk N. A. Sycheva S. L. Yunga L. M. Bogomolov Y. Yagi 《Izvestiya Physics of the Solid Earth》2010,46(3):230-243
For evaluating the deformations of the Earth’s crust in the Northern Tien Shan, we calculated the mode and intensity of the
seismotectonic deformations (STD) for this region. The input for these calculations were the catalog data on the focal mechanisms
of earthquakes, obtained by wave inversion of the signals recorded at the Kyrgyz seismic network (KNET) for the period 1994–2006.
In the construction of STD maps, a modern approach to the classification of seismotectonic deformations was applied. This
approach distinguishes eleven typical patterns of deformation. The areal distributions of the Lode-Nadai coefficient, as well
as of the vertical component and the aspect angle of the deformed state were obtained. At the same time, based on the GPS
measurements in the Northern Tien Shan during 1994–2006, the rates of dilatation and shear deformation of the Earth’s crust
were estimated. A comparison between the directions of strain axes derived from the GPS data and from the earthquake focal
data is carried out. 相似文献
20.
The Doroud segment of the Main Recent Fault (“MRF”) is studied by installing a local seismic network of 35 short-period stations
for a period of 13 weeks from 21 June 2007 to 19 September 2007 in the Silakhur region of the Zagros continental collision
zone, close to the epicenter of the 31 March 2006 Silakhur earthquake (M
w
∼ 6.1). Our seismic network also covers the Qale-Hatam and Vanaei segments of the MRF and part of the Nahavand fault. We
investigate the geometry and mechanism of the causative fault(s) of the 2006 Silakhur earthquake using aftershocks recorded
by the dense local network. Most of the aftershocks in this region are located at a depth of 4–11 km, shallower depth than
usual for other seismic zones in the Zagros. The distribution of the aftershocks along the course of the river indicates that
older faults in the Silakhur region have been activated during the 2006 earthquake and only a few aftershocks have occurred
on the Doroud fault. Tensional and compressional components in the northern part of the Doroud fault are interpreted as a
pull-apart basin which has been activated by the right-lateral strike-slip movement of the Doroud fault. 相似文献