Seismic Detection System Research Articles

Development and Testing of a High-Resolution Three-Dimensional Seismic Detection System for Gas Hydrate

As a novel type of mineral resource, gas hydrate has received a considerable amount of attention worldwide. This seismic detection method can detect abnormal phenomena such as the BSR, blank zones, velocity anomalies and polarity inversion of gas hydrate and become an important method of gas hydrate detection. The occurrence area of gas hydrate in the South China Sea is usually buried deep beneath the seabed. The current method cannot meet the needs of the shape and structure detection of gas hydrate deposits. With the support of the National Key R&D Program of China, some key technologies have led to developmental breakthroughs, such as ultra-high-energy plasma sources, small-group-interval high-resolution seismic streamers, and distributed three-dimensional seismic acquisition. The seismic profile obtained north of the South China Sea shows that the stratum penetration depth reaches nearly 1000 m at a depth of 1500 m, and the vertical resolution is better than 1.5 m. This system can serve the needs of high-resolution exploration of gas hydrate resources.

Design of an active-source seismic detection system based on illumination analysis and migration imaging experiments: considering the Zhuxi mining area as an example

Design of an active-source seismic detection system based on illumination analysis and migration imaging experiments: considering the Zhuxi mining area as an example

Design and Implementation of a Multi-Channel High-Precision Electromagnetic Seismic Joint Detection System

The developments in deep earth exploration are promoted by advanced methods and corresponding high-end detection instruments [1], wherein a single geophysical exploration approach can yield multiple solutions. In the mid-nineteenth century, scientific methods were first used to investigate the earth's internal structure. In an initial attempt at seismic exploration, R. Mallet, in 1845, used artificially excited seismic waves to measure the propagation speed of elastic waves in the earth's crust [2], [3]. In comparison to the seismic method, the use of electromagnetic approaches has been very limited. In 1955, a Soviet scholar Tikhonov and a French scholar Cagniard proposed a geophysical exploration method called “Magnetotelluric (MT) Sounding,” which employs natural alternating electromagnetic fields to study the earth's electrical structure [2]–[4]. To address the limitations like natural-field source randomness and a weak signal associated with MT, D. W. Strangway and M. Goldstein proposed a detection method using artificial sources (CSAMT) in the early 1970s [5], [6].

Seismic Performance of New Fabricated Lightweight Herringbone Support Seismic Wall Based on ZigBee Sensor Technology

Reinforced concrete antiseismic wall structure has great load-bearing capacity and resistance to lateral displacement and is widely used as high-rise and super high-rise buildings. At present, in the seismic testing of buildings, the vibration signals that simulate earthquakes are transmitted through a wired transmission system for analysis after a certain amount of processing, and the seismic performance of the building is tested. The purpose of this paper is to analyze and study the seismic resistance of a newly fabricated lightweight herringbone braced seismic wall based on ZigBee sensor technology. In this paper, firstly, the research and exploration of the building seismic capability detection system using ZigBee technology wireless sensor are carried out, and the building seismic capability detection system is a wireless sensor network using ZigBee technology; it measures the seismic performance of the building by detecting the acceleration values of key parts in the building model. Then, the seismic design response spectrum is proposed, and the modal analysis is carried out at the same time, and the mode decomposition response spectrum method is given. Then, the seismic performance of the reasonable RC support lightweight herringbone support seismic wall was analyzed, and the seismic performance of the lightweight herringbone support structure was studied at the same time. The experimental results show that with the increase in the size of the RC support section, the bearing capacity and seismic performance of the lightweight herringbone support seismic wall are improved. The displacement ductility coefficient obtained is greater than 4, and the energy dissipation coefficient is 1.56, which meets the seismic requirements of the structure.

Seismic Wave-Based Human Movement Detection and Storage System

Seismic Wave-Based Human Movement Detection and Storage System

Characterizing snow instability with avalanche problem types derived from snow cover simulations

Snow cover models support avalanche forecasting. However, despite much development to derive snow instability from snow cover model output, snow cover models presently do not provide information on avalanche problem types – an essential element to describe avalanche danger. We present an approach to detect, track and assess weak layers in snow cover model output data and assess the related avalanche problem types. We classify different avalanche situations into new snow, wind slab, persistent weak layer and wet-snow problems for either natural or artificial avalanche release. We demonstrate the applicability of this approach with both SNOWPACK and Crocus model output for several winter seasons at Weissfluhjoch, Switzerland, and two sites in Western Canada. At Weissfluhjoch, simulation results from both models coincided reasonably well with avalanche activity recorded with a seismic avalanche detection system. Over a 16-year period both models produced similar frequencies of avalanche problems. At the two Canadian sites frequencies of simulated avalanche problem types agreed fairly well with the observed frequencies. The results provide confidence that avalanche problem types can be simulated in different snow climates and that changes due to climate change can be studied. Moreover, the approach to assess avalanche problem types holds potential to support operational avalanche forecasting.

TBM-Mounted Seismic Ahead-Prospecting for Fast Detecting Anomalous Geology Ahead of Tunnel Face

Although performing tunnel excavation using tunnel boring machines (TBMs) is rapid, it is susceptible to the unexpected geological changes located in front of the tunnel face. Seismic detection methods are useful to detect local geological conditions in front of the tunnel face. However, manual detection is time consuming and may interfere in realizing rapid excavation by TBMs. Therefore, this study proposes an automated seismic detection system that is mounted on a TBM for rapidly imaging anomalous zones in front of the tunnel face. The system consists of an automated data acquisition system and a data processing system. The automated data acquisition system allows reducing the data acquisition time. To reduce the data processing time, the data processing system images the anomalous zones based on a modified Coppens' method. The proposed system has been mounted on TBMs and verified based on field tests.

Proposal for a System Model for Offline Seismic Event Detection in Colombia

This paper presents an integrated model for seismic events detection in Colombia using machine learning techniques. Machine learning is used to identify P-wave windows in historic records and hence detect seismic events. The proposed model has five modules that group the basic detection system procedures: the seeking, gathering, and storage seismic data module, the reading of seismic records module, the analysis of seismological stations module, the sample selection module, and the classification process module. An explanation of each module is given in conjunction with practical recommendations for its implementation. The resulting model allows understanding the integration of the phases required for the design and development of an offline seismic event detection system.

Comparison of Signal-Analysis Techniques for Seismic Detection System for High-Speed Train Data: Effect of Bridge Structures.

This study evaluated the earthquake warning system for high-speed trains using onboard accelerometers instead of expensive seismometers. Onboard accelerometers measure the train data additional to the earthquake acceleration. The measured earthquake acceleration could also be modified by railroad-supporting bridges. To develop the data analysis system, the virtual onboard data sets are synthesized using the train acceleration data and earthquake data. Not only the earthquake acceleration data but also the earthquake responses of bridges are used for the virtual onboard data synthesis. For the analysis of synthesized data, the short-time Fourier Transform (STFT), the wavelet transform (WT), and Wigner–Ville Distribution (WVD) methods have been compared. Results show that WVD provides the best detection performance while the computational costs are large.

НЕКОТОРЫЕ АСПЕКТЫ МАТЕМАТИЧЕСКОЙ ОБРАБОТКИ И СОЗДАНИЯ АЛГОРИТМА ОБНАРУЖЕНИЯ СЕЙСМИЧЕСКИХ СОБЫТИЙ

Based on the data of a three-component station, it is possible to use a seismic event detection system to solve problems of recording seismic events, which automatically determines the location of seismic events by analyzing three-component records of one station. Information processing requires methodological developments related to the creation of algorithms and programs for extracting a useful signal, determining the time of the entry of seismic waves, the values of the maximum amplitudes, the corresponding period of vibrations and the coordinates of the earthquake location.

A towed-type shallow high-resolution seismic detection system for coastal tidal flats and its application in Eastern China

Abstract Restricted by detective equipment and tidal influence seriously, coastal tidal flats are often treated as the transition belt of paralic zone in terms of seismic detection, causing low exploration degree and accuracy in these areas. What is worse, conventional shallow seismic method has a complex system and low acquisition efficiency, which cannot meet the requirements for high-efficiency acquisition in tidal flats. To solve these problems, a towed shallow seismic detection system is specially established for coastal tidal areas, mainly including electric spark source and towable ship-type geophone strings. After comparisons, some advantages of this method are obtained, such as high efficiency, low cost and reliability. Furthermore, its detective accuracy and depth can reach the meter level and more than 800 m, respectively. Then, a series of shallow seismic processing methods are improved for coastal tidal flats. Deconvolution and velocity analysis are emphatically introduced to multiple-wave attenuation. A short array of this towable detection can keep a far more effective wave from being cut off because of its small NMO stretch. Last but not least, the towable method in coastal tidal-flat zones can successfully identify the stratigraphic structure, interface, palaeo-channel, concealed active fault and submarine shallow gas in Jiangsu Coast, Eastern China, which has great practical results and significance for geological and environmental surveys, as well as scientific geo-hazard prevention and mitigation in these areas.

The study on the novel distributed vibration sensing system based on the adjacent FBGs reflected lights interference

Due to the different polarization states of the reflected light on the two arms of conventional Michelson interferometer, polarization fading of the interferometric signal occurs when environmental perturbations and noise are existing. To solve this problem, in this paper, we design a novel distributed FBG array vibration sensing system based on the interference caused by the reflected signals of the adjacent FBGs. By controlling the pulse width of the input pulse, The reflected light of the adjacent FBGs can interfere on the 3*3 coupler, and we can judge the outside invasion by analyzing the characteristics of the interference signal. The system can demodulate the driving signal with the frequency range of 10 Hz–50 Hz. Comparing with conventional vibration acceleration deteceing methods, the proposed system has the higher sensitivity, wider bandwidth, less response time and better spatial resolution. Meanwhile, the proposed system has sufficient sensing areas which can serve as the high-capacity interferometric seismic detection system.

Characteristic Analysis of Pulse Discharge Hypocenter

This paper described a pulse discharge hypocenter system, which can be used to carry out arc pulse discharge and corona discharge. At the same time, an experimental platform was set up, which consists of a pulse hypocenter system, a voltage–current measurement unit, a digital oscilloscope and a seismic detection system. On this basis, the experimental study of arc discharge and corona discharge was carried out at different voltages, different electrode gaps, and different excitation positions. In detail, the curves of the voltage and current of multiple discharges were put in the same axis to show by using the data input function of the Origin Pro 9.0 software, so as to contrast and analysis the data. In addition, at the same time of each discharge, 50 detectors inserted into the different ground received real-timely seismic waves coming from the source. Then, the detected seismic-wave intensities were recorded by the central recording system. Through the analysis and processing, the characteristics of corona discharge and arc discharge were summarized and compared, which can provide a useful reference for the design of pulse discharge hypocenter.

Experimental investigations on seismic damage monitoring of concrete dams using distributed lead zirconate titanate sensor network

Seismic damage detection of concrete dams has always attracted much attention in hydraulic structure community. In this article, a novel seismic damage detection system was developed to perform seismic damage monitoring in concrete dams. As its importance in achieving the dam damage detection, the arrangement of a distributed lead zirconate titanate sensor network was introduced in detail. A dam model system with a distributed lead zirconate titanate sensor network was used as an object for verification. A shaking table was used to simulate the earthquake ground motion for the object to be tested. The seismic damage detection system could be used in not only the seismic damage process monitoring by measuring the dynamic stress history but also the distributed detecting of the dam damaged region. By analyzing the sensor signals, the emergence and development of the structural damages could be monitored timely. A damage index matrix was presented to evaluate the damage status of the dam in different paths. The experimental results verified the timeliness and the effectiveness of the proposed method.

National Seismic Intensity Rapid Reporting and Early Warning Project: Opportunity and Challenge of Seismic Network

China has already started the "National Seismic Intensity Rapid Reporting and Early Warning" project (called the "National Early Warning project" for short), which will build the world largest seismic intensity rapid reporting and early warning observation system with a total of more than 10000 stations, and will enhance the national earthquake disaster mitigation capacity and improve the service level significantly. It will be of great practical significance to analyze the relationship between the "National Early Warning project" and the existing seismic monitoring network. Studies have indicated that the "National Early Warning project" would bring a rare development opportunity to the existing seismic monitoring network, including service in earth science research,earthquake emergency response, and earthquake forecasting. Some new problems have been put forward, including the stability and reliability of the system operation, the availability of the intensity data, the comprehensive utilization of the observed data, and sharing service of the cross subject data. In order to conduct the "National Early Warning project" successfully, from the point of view of seismic observation subject, we also need to carry out the research on the operation mode for the mass observation network and optimizing seismic networks, key technology, detection system and practical work for earthquake early warning.

Automatic data processing and analysis system for monitoring region around a planned nuclear power plant

Abstract. The Institute of Seismology of University of Helsinki is building a new local seismic network, called OBF network, around planned nuclear power plant in Northern Ostrobothnia, Finland. The network will consist of nine new stations and one existing station. The network should be dense enough to provide azimuthal coverage better than 180° and automatic detection capability down to ML −0.1 within a radius of 25 km from the site.The network construction work began in 2012 and the first four stations started operation at the end of May 2013. We applied an automatic seismic signal detection and event location system to a network of 13 stations consisting of the four new stations and the nearest stations of Finnish and Swedish national seismic networks. Between the end of May and December 2013 the network detected 214 events inside the predefined area of 50 km radius surrounding the planned nuclear power plant site. Of those detections, 120 were identified as spurious events. A total of 74 events were associated with known quarries and mining areas. The average location error, calculated as a difference between the announced location from environment authorities and companies and the automatic location, was 2.9 km. During the same time period eight earthquakes between magnitude range 0.1–1.0 occurred within the area. Of these seven could be automatically detected. The results from the phase 1 stations of the OBF network indicates that the planned network can achieve its goals.

Field trial of seismic recording using distributed acoustic sensing with broadside sensitive fibre‐optic cables

ABSTRACTDistributed acoustic sensing is an emerging technology using fibre‐optic cables to detect acoustic disturbances such as flow noise and seismic signals. The technology has been applied successfully in hydraulic fracture monitoring and vertical seismic profiling. One of the limitations of distributed acoustic sensing for seismic recording is that the conventional straight fibres do not have broadside sensitivity and therefore cannot be used in configurations where the raypaths are essentially orthogonal to the fibre‐optic cable, such as seismic reflection methods from the surface. The helically wound cable was designed to have broadside sensitivity. In this paper, a field trial is described to validate in a qualitative sense the theoretically predicted angle‐dependent response of a helically wound cable. P‐waves were measured with a helically wound cable as a function of the angle of incidence in a shallow horizontal borehole and compared with measurements with a co‐located streamer. The results show a similar behaviour as a function of the angle of incidence as the theory. This demonstrates the possibility of using distributed acoustic sensing with a helically wound cable as a seismic detection system with a horizontal cable near the surface. The helically wound cable does not have any active parts and can be made as a slim cable with a diameter of a few centimetres. For that reason, distributed acoustic sensing with a helically wound cable is a potential low‐cost option for permanent seismic monitoring on land.

P-S Time Observation based on Laser Interferometer Seismic Signal Data

In seismic signal detection, it is important to detect seismic wave and P-S wave arrival time. Seismometers or accelerometers which are used as seismic wave measurement system have some limits to detect seismic signal. In order to overcome these limits, we propose the seismic wave measurement device based on a heterodyne laser interferometer. Heterodyne laser interferometer is used as the distance measurement device which has measurable range from nanometer to several meters. Therefore we model seismic wave detection system based on heterodyne laser interferometer to measure P-S time for epicenter. Finally, we use STA/LTA algorithm to detect P-S time accurately. It is shown that heterodyne laser interferometer can be used as seismic detection device.

Reconstructing the trajectory of a moving object in a seismic detection system with a limited number of sensors

We present results of our work on direction finding for moving objects based on analyzing the correlation function of seismic signals from seismic detectors spread out in space. Based on the bearings of a moving object from several direction finding sensors, we propose an algorithm for trajectory reconstruction. To refine the trajectory, we use the Kalman filter and the extended Kalman filter and show comparison results for these filters on real world signals.

Seismic detection using support vector machines

This study describes research to design a seismic detection system to act at the level of a seismic station, providing a similar role to that of STA/LTA ratio-based detection algorithms.In a first step, Multi-Layer Perceptrons (MLPs) and Support Vector Machines (SVMs), trained in supervised mode, were tested. The sample data consisted of 2903 patterns extracted from records of the PVAQ station, one of the seismographic network’s stations of the Institute of Meteorology of Portugal (IM). Records’ spectral variations in time and characteristics were reflected in the input ANN patterns, as a set of values of power spectral density at selected frequencies. To ensure that all patterns of the sample data were within the range of variation of the training set, we used an algorithm to separate the universe of data by hyper-convex polyhedrons, determining in this manner a set of patterns that have a mandatory part of the training set. Additionally, an active learning strategy was conducted, by iteratively incorporating poorly classified cases in the training set. The proposed system best results, in terms of sensitivity and selectivity in the whole data ranged between 98% and 100%. These results compare very favourably with the ones obtained by the existing detection system, 50%, and with other approaches found in the literature.Subsequently, the system was tested in continuous operation for unseen (out of sample) data, and the SVM detector obtained 97.7% and 98.7% of sensitivity and selectivity, respectively. The classifier presented 88.4% and 99.4% of sensitivity and selectivity when applied to data of a different seismic station of IM.Due to the input features used, the average time taken for detection with this approach is in the order of 100s. This is too long to be used in an early-warning system. In order to decrease this time, an alternative set of input features was tested. A similar performance was obtained, with a significant reduction in the average detection time (around 1.3s). Additionally, it was experimentally proved that, whether off-line or in continuous operation, the best results are obtained when the SVM detector is trained with data originated from the respective seismic station.