Automatic real-time event detection for seismic networks

Waugh, Georgie; Laughlin, John S.

doi:10.1016/0098-3004(84)90043-8

“…An input low-pass filter was provided for each processor channel to ensure that aliasing components of the high-frequency data were not recorded. Each triggering processor channel contained features already developed for previous seismic triggering systems (Houliston et al 1982), including a CMOS processor, an analogue-to-digital (A-D) converter, a digital-to-analogue (D-A) converter and 16 k bytes of CMOS random-access memory sufficient to provide four seconds of pre'trigger data. An option switch and associated logic circuitry for recording control were provided.…”

Section: Event-triggered Recording Systemmentioning

confidence: 99%

“…An automatic event-triggered recording system (Houliston et al 1982;Browitt et al 1983) was therefore operated for several months, to accumulate samples of local noise and any natural analogue data Amplifier Geophone Modulators roof-falls. No roof-fall activity was recorded during this period in the mine, which appears to be stable.…”

Section: Field Experimentsmentioning

confidence: 99%

Microseismic techniques for monitoring incipient hazardous collapse conditions above abandoned limestone mines

Miller

¹

,

Richards

²

,

McCann

³

et al. 1989

QJEGH

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The progressive collapse of abandoned limestone mines over many decades has led to problems of general subsidence and crown-hole formation in parts of the West Midlands. The substantial size and extent of the voids makes the cost of infilling all of the mines prohibitively expensive, at least in the short term. One option is to monitor the workings to identify active areas and assess the rate of collapse. This would provide government and local authorities with additional criteria for establishing priorities for remedial action. Monitoring of the condition of the mines is made difficult by their general inaccessibility, but it was thought that the detection of microseismic energy associated with rock failures and roof-falls might provide a useful method of remote monitoring. This paper summarizes a series of studies designed to develop and field test a method of monitoring microseismic events and discriminating them from the many other seismic sources. Experiments involving simulated roof-falls in an accessible (air-filled) mine indicated that the most detectable source of seismic energy is generated by debris impacting on the mine floor, rather than by stress-induced rock failure. Consequently, the energy is in a lower frequency range (around 10 to 300 Hz), than was at first anticipated.Trials using both continuous and triggered recording, with a variety of transducers, installation techniques and network configurations, provided useful information regarding optimum network design for the discrimination of roof-falls. On the basis of these findings a seismic network was successfully implemented to monitor roof-falls during a mine infill trial. Finally, an experimental network of instruments in boreholes at a water-filled mine demonstrated, by means of artificial seismic sources, that the technique can also be applied to flooded, inaccessible mines.

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“…Certainly, the instrumentation and analytical methods developed for the location of fractures propagating through the rock mass following hydraulic fracturing described by Batchelor et al (1983) can be directly applied to landslides. The manpower requirements can be considerably reduced by using the automatic triggering system for recording events developed by Houliston et al (1982) and this does mean that continuous on-line monitoring can be achieved. Work carried out by the British Geological Survey on the Taren landslide in South Wales indicates that this is essential as it is extremely difficult to use manual recording methods with an intermittent process such as microseismic activity.…”

Section: Microseismic Monitoringmentioning

confidence: 99%

Engineering Geophysics

1988

QJEGH

15

0

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Synopsis A Working Party was set up in February 1982 by the Engineering Group of the Geological Society. Members were chosen from different academic institutions, government bodies and industry to provide a balance of expertise and experience in the application of geophysical methods to engineering practice. A list of the members of the Working Party is given at the end. The Working Party has presented the report in five main sections. An introductory section defines the objectives of engineering geophysics and makes recommendations on the design and implementation of geophysical surveys. Section 2 considers the applications and limitations of geophysical methods and the use of computers in the acquisition, interpretation and presentation of geophysical data. The following section is essentially a state of the art review of all appropriate geophysical techniques and procedures for specific geological targets, other than measurements from the air. Case studies are provided to illustrate the more commonly used methods such as seismic refraction profiling, electrical resistivity sounding and electromagnetic investigation of ground conductivity variations. Section 4 considers the application of geophysical methods to six main areas of ground engineering activity and can be used either directly or in conjunction with other sections of the report. Geophysical assessment of soil and rock properties is covered under a separate heading because of its increasing importance in engineering practice and the corresponding anticipated demand for a review of currently used methods. A further section in the form of a Bibliography is provided as a supplement to these reports. Selected bibliography Bulletin of the Association of Engineering Geologists (USA) Bulletin of the International Association of Engineering Geology (France) Bulletin of the Australian Society of Exploration Geophysicsists (Australia) Engineering Geology (Elsevier Scientific Publishing Co., The Netherlands) Geoexploration (Elsevier Scientific Publishing Co., The Netherlands) Geophysical Prospecting (European Association of Exploration Geophysicists, The Netherlands) Geophysics (Society of Exploration Geophysicists, USA) Geotechnique (British Geotechnical Society, UK) Ground Engineering (Geo Publications Ltd, UK) Ground Water (National Water Well Association, USA) The Hydrographic Journal (The Hydrographic Society, UK) Journal of Geotechnical Engineering (American Society of Civil Engineers. Formerly called Journal of the Geotechnical Engineering Division 1974 up to 1983, and prior to that, Journal of the Soil Mechanics and Foundation Division of the ASCE ; USA) Quarterly Journal of Engineering Geology (The Geological Society, UK) These journals should be scanned regularly for new and up-to-date techniques and case histories. The following list of references to articles, papers and textbooks dealing with aspects of engineering geophysics may be considered to be the basic source reading for those involved in the practice of engineering geophysics.

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“…This approach involves complicated computation and takes more time, making it unsuitable for on-line real time seismic applications. Houliston et al (1984) have described a short-term to long-term average ratio algorithm for a multichannel seismic network system. The algorithm based on Short Term Average to Long Term Average (STA/ LTA) principle is found more suitable for earthquakes and Strong Motion detection.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of seismic events detection algorithms

Sharma

¹

,

Kumar

²

,

Murthy

³

2010

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Identification of seismic events from continuously recorded seismic data in real-time through a Digital Seismic Data Recording system is a difficult task. Despite the vast amount of research in this field, the signal processing and event parameters discrimination algorithms have not yet fully come of age. Presently, we have a wide spectrum of trigger algorithms, ranging from a very simple amplitude threshold type to the sophisticated ones based on pattern recognition approaches. Some of the other approaches use adaptive technique and neural network methods. Researchers are continuously making efforts for the development of algorithms using various techniques, which produce minimum false trigger. Some approaches have been reported which are accurate for detecting first phase of events and take minimum possible computational time. In this paper several approaches for detecting event signals in background noise are presented and their precision evaluation is discussed.

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Automatic real-time event detection for seismic networks

Cited by 16 publications

References 4 publications

Microseismic techniques for monitoring incipient hazardous collapse conditions above abandoned limestone mines

Microseismic techniques for monitoring incipient hazardous collapse conditions above abandoned limestone mines

Engineering Geophysics

Evaluation of seismic events detection algorithms

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