A real-time digital seismic event detection and recording system for network applications

1982 ◽  
Vol 72 (6A) ◽  
pp. 2339-2348
Author(s):  
Andrew J. Michael ◽  
Stephen P. Gildea ◽  
Jay J. Pulli
Keyword(s):  
Real Time ◽  
Event Detection ◽  
Seismic Event ◽  
Weather Conditions ◽  
Recording System ◽  
Walsh Transform ◽  
Long Period ◽  
Short Period ◽  
Seismic Event Detection ◽  
Period Data

abstract A real-time digital seismic event detection and recording system has been developed for the MIT Seismic Network. The system has been designed specifically for an environment of low natural seismic activity and for surface stations which are often influenced by weather conditions and cultural noise. The system runs on an HP-1000 computer and can handle up to 16 channels of short- and long-period data. The structure of the system centers around the event detectors, one for short-period data and one for long-period data. These detectors base their decisions on a metric computed from the Walsh transform of the data. This allows them to detect changes in the amplitude of the waveform as well as frequency shifts. Detections at several stations are correlated to prevent glitches from triggering the detector. Present operation successfully saves those events that are large enough for analysis and leaves 23 of the computer available for general timesharing use.

An automatic seismic signal detection algorithm based on the Walsh transform

1981 ◽  
Vol 71 (4) ◽  
pp. 1351-1360
Author(s):  
Tom Goforth ◽  
Eugene Herrin
Keyword(s):  
Signal Detection ◽  
Real Time ◽  
Seismic Signal ◽  
Detection Algorithm ◽  
Machine Language ◽  
Walsh Transform ◽  
Time Signal ◽  
Data Systems ◽  
Detection Capability ◽  
Short Period

abstract An automatic seismic signal detection algorithm based on the Walsh transform has been developed for short-period data sampled at 20 samples/sec. Since the amplitude of Walsh function is either +1 or −1, the Walsh transform can be accomplished in a computer with a series of shifts and fixed-point additions. The savings in computation time makes it possible to compute the Walsh transform and to perform prewhitening and band-pass filtering in the Walsh domain with a microcomputer for use in real-time signal detection. The algorithm was initially programmed in FORTRAN on a Raytheon Data Systems 500 minicomputer. Tests utilizing seismic data recorded in Dallas, Albuquerque, and Norway indicate that the algorithm has a detection capability comparable to a human analyst. Programming of the detection algorithm in machine language on a Z80 microprocessor-based computer has been accomplished; run time on the microcomputer is approximately 110 real time. The detection capability of the Z80 version of the algorithm is not degraded relative to the FORTRAN version.

scholarly journals Capabilities of Satellite-Based Precipitation to Estimate the Spatiotemporal Variation of Flood/Drought Class in Poyang Lake Basin

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Xianghu Li ◽  
Qi Zhang ◽  
Xuchun Ye
Keyword(s):  
Poyang Lake ◽  
Rainfall Data ◽  
Data Series ◽  
Lake Basin ◽  
Long Period ◽  
Poyang Lake Basin ◽  
Short Period ◽  
Period Data ◽  
Temporal And Spatial ◽  
Drought Classes

Poyang Lake basin is one of the most frequently affected areas by a variety of flood or drought events in China. Satellite-based precipitation data have greatly improved their temporal and spatial resolution in recent years, but the short length of records limited their applications in some fields. This paper compared and evaluated the creditability of using a short period data series to estimate the statistics characteristics of long period data series and investigated the usefulness of TRMM rainfall data for monitoring the temporal and spatial distribution of flood/drought classes by theZindex method in Poyang Lake basin. The results show that (1) the 1998–2010 data series are sufficiently robust to depict the statistics characteristics of long period data; (2) the intra-annual distribution and interannual variability of flood/drought classes based on TRMM rainfall data matched well with the results from rain gauges data; (3) the spatial agreement between TRMM and interpolated gauges rainfall varied with the precipitation characteristics; and (4) TRMM rainfall data described the similar spatial pattern of flood/drought classes with the interpolated gauges rainfall. In conclusion, it is suitable and credible for flood/drought classes evaluation based on the TRMM rainfall data in Poyang Lake basin.

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