Background seismicity and seismic monitoring in the Lai Chau reservoir area

Abstract Reservoir-triggered seismic activity depends not only on the technical characteristics of the future reservoir (filling volume, the height of water column) but also on the seismo-tectonics and the natural seismic processes occurring in the area before construction of an artificial reservoir. Passive seismic monitoring was realised near Lai Chau (Vietnam) before the impoundment started. It allowed exploration of the natural seismicity in the area of the future dam. Locations of seismic events several months prior to the reservoir impoundment were observed with ten stations installed in the reservoir vicinity. Events were mainly located near the dam along the Da river headwaters fault. However, only four stations were available for the entire period before the impoundment. Despite the network limitations, completeness of seismic catalogue and b value were determined and may be used as a baseline for analysis of the seismicity in this area after impoundment. The magnitude completeness level is significantly smaller than in the broader seismogenic zones covering an area of the dam. The b value differs from the results obtained for regional seismicity of Northeastern Vietnam. The capability of the local network for moment tensor inversion was estimated with the use of synthetic data tests. Test results provided the requirements for the station number according to azimuthal coverage of the network to obtain the reliable full moment tensor (MT) solution. Preliminary analysis of the seismic activity after Lai Chau reservoir impoundment indicates some changes in activity related to the impoundment and reservoir exploitation.

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PROBLEMS OF SEISMIC HAZARD IN CONNECTION WITH TELLURIC AND COSMIC PROCESSES

Геология и геофизика Юга России ◽

10.23671/vnc.2016.1.20721 ◽

2016 ◽

Author(s):

А.Д. Жигалин ◽

О.Г. Попова

Keyword(s):

Seismic Hazard ◽

Seismic Activity ◽

Seismic Risk ◽

Seismic Monitoring ◽

Tectonic Activity ◽

Geological Environment ◽

Passive Seismic

На примере изучения временных вариаций геодинамических свойств геологической среды в районах с различной сейсмической активностью показана эффективность пассивного сейсмического мониторинга при оценке уровня сейсмической опасности и сейсмического риска. Показано влияние теллурических (земных) и космических факторов на режим сейсмичности в районах с разной тектонической активностью. On an example of the geological environment geodynamic properties temporary variations studying in areas with various seismic activity efficiency of passive seismic monitoring is shown at an assessment of a level of seismic danger and seismic risk. Influence of telluric (Earth) and space factors on a mode of seismicity in areas with different tectonic activity is shown.

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Automatic monitoring of crustal seismic activity in Galati region of southeastern Romania using full waveform-based approach

10.5194/egusphere-egu2020-21361 ◽

2020 ◽

Author(s):

Dragos Tataru ◽

Natalia Poiata ◽

Bogdan Grecu

Keyword(s):

Seismic Activity ◽

Velocity Structure ◽

Automatic Monitoring ◽

Seismic Monitoring ◽

Local Network ◽

Earthquake Catalog ◽

Small Magnitude ◽

Seismic Swarm ◽

Full Waveform ◽

Shallow Velocity Structure

In September&#8211;November 2013 a seismic swarm occurred in Galati region of southeastern Romania. The area was previously known as characterized by low seismic activity along the major crustal faults. During the period of swarm, between September 23rd and November 5th, over 1000 events with the magnitudes (Ml) of 0.2&#8211;4.0, located at the depth of 5&#8211;10 km, have been detected. Despite the relatively small magnitude, events generated ground motions that were well felt by local people, leading to panic in the area. The proximity of active oil fields caused additional annoyance.Advanced seismic monitoring in the region started in 2013 with deployment of mobile seismic stations immediately after the beginning of the swarm. Additionally, active seismic measurements were performed in order to characterize the shallow velocity structure at specific sites. Starting from July 2015 new permanents stations were installed in the area marking the beginning of Galati local network development. The routine seismic catalog derived using the acquired data and applying the standard detection and location techniques pointed that area continues to be seismically active, however with low rate of activity and magnitude of events. These made it a perfect study case for development of new advanced schemes for seismic monitoring of the regions with low and complex seismicity aiming on an understanding of the phenomenon underlying the 2013 seismic swarm as well as the current seismic activity in the area.We developed and automatic monitoring scheme based on the network-based full waveform detection and location method BackTrackBB (Poiata et al. 2016) that exploits the coherency of signals&#8217; statistical features recorded across the seismic network. Once extracted from the flux of continuous data, seismic events are compared against the database of previously detected events using coherency and allowing to identify potential repeaters or multiplets. The earthquake catalog provided by the system starting from 2017 was compared to the routine ROMPLUS catalog of NIEP showing an increase in the number of detected events by the order of 3. We present the details of the implementation and discuss its advantages and drawbacks.

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Integrated Active and Passive Seismic Monitoring at the Decatur CCS Project

SSRN Electronic Journal ◽

10.2139/ssrn.3365916 ◽

2019 ◽

Author(s):

Bettina Goertz-Allmann ◽

D. Kühn ◽

K. Iranpour ◽

M. Jordan ◽

Benjamin Udo Emmel ◽

...

Keyword(s):

Seismic Monitoring ◽

Passive Seismic

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Basic principles for building seismic monitoring systems in rockburst-hazardous coal seam mining

Gornyi Zhurnal ◽

10.17580/gzh.2021.01.02 ◽

2021 ◽

pp. 8-12

Author(s):

E. E. Razumov ◽

◽

S. M. Prostov ◽

G. D. Rukavishnikov ◽

S. N. Mulev ◽

...

Keyword(s):

Seismic Activity ◽

Average Energy ◽

Seismic Monitoring ◽

Acoustic Properties ◽

Signal Frequency ◽

Monitoring Systems ◽

Seismic Events ◽

Seismic Monitoring Systems ◽

Seismic Sensors ◽

Seam Mining

The main directions of development of seismic monitoring systems in underground mineral mining are analyzed. The expediency of passive registration of natural seismic activity is proved, which provides prediction of geodynamic phenomena by locating the centers of seismic events and determining their energy level. The methods of active seismic monitoring (seismic tomography, cross-borehole survey, recording of seismic signal from a rock-breaking tool) are technically more difficult to implement. The promising methods for processing seismic information are geolocation, neural network technology, cluster analysis, and integration with numerical stress–strain analysis of and changes in acoustic properties of rock mass. The configuration of the platform developed at VNIMI and the GITS seismic monitoring system, which includes from 6 to 12 three-component seismic sensors installed permanently in wells or on pedestals, is described. The detailed layouts of seismic sensors at recording points and in gateways in extraction panels are presented. The main technical characteristics of GITS are given: the signal frequency range is 0.1–1000 Hz, the minimum recorded signal level is 0.01 mV. The main test data of GITS in Komsomolskaya mine of Vorkutaugol are described: the average annual levels of seismic activity and energy of seismic events are found to be relatively stable; the relationship between seismic event with the maximum total energy and the alternating increment in the relative criterion is defined, and the local increase in the average energy of a single event in time from the moment the main roof caving is identified. Aimed to substantiate the regional and local prediction criteria of probability of geodynamic events caused by confining pressure, VNIMI implements integrated research in mines in different regions.

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