Three component long-period data for the 1949 South Puget Sound, Washington earthquake

1986 ◽  
Author(s):  
G.E. Baker
Keyword(s):  
Puget Sound ◽  
Long Period ◽  
Period Data

LONG‐PERIOD SIGNAL PROCESSING RESULTS FOR THE LARGE APERTURE SEISMIC ARRAY

Geophysics ◽  
1969 ◽  
Vol 34 (3) ◽  
pp. 305-329 ◽  
Author(s):  
J. Capon ◽  
R. J. Greenfield ◽  
R. T. Lacoss
Keyword(s):  
Signal Processing ◽  
Surface Wave ◽  
Maximum Likelihood ◽  
Surface Waves ◽  
Body Wave ◽  
Seismic Array ◽  
Seismic Events ◽  
Long Period ◽  
Large Aperture ◽  
Period Data

The results of a series of off‐line signal processing experiments are presented for long‐period data obtained from the Large Aperture Seismic Array (LASA) located in eastern Montana. The signal‐to‐noise ratio gains obtained with maximum‐likelihood processing, as well as other simpler forms of processing, are presented for body‐wave as well as surface‐wave phases. A discussion of the frequency‐wavenumber characteristics of the noise which led to these results is also given. On the basis of these experiments, several recommendations are made concerning optimum long‐period array configurations and on‐line or off‐line processing methods. The usefulness of maximum‐likelihood processing in suppressing an interfering teleseism is demonstrated. An experiment is given in which maximum‐likelihood processing achieved about 20 db suppression of an interfering teleseism, while simpler forms of processing such as beam‐forming obtained about 11 db. The matched filtering of surface waves using chirp waveforms is shown to be highly effective. A useful discriminant for distinguishing between natural seismic events and underground nuclear explosions, using both the long‐period and short‐period data, was found to be the relationship between the surface‐wave and body‐wave magnitudes. Measurements of this discriminant made on events from four tectonic regions of the earth are presented. It is shown that 60 and 100 percent detectability of surface waves for natural seismic events from the Central Asian‐Kurile Islands‐Kamchatka region occurs at about LASA body‐wave magnitudes 4.5 and 4.9, respectively.

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.

The Seismic Research Observatory

1976 ◽  
Vol 66 (6) ◽  
pp. 2049-2068 ◽  
Author(s):  
Jon Peterson ◽  
Howell M. Butler ◽  
L. Gary Holcomb ◽  
Charles R. Hutt
Keyword(s):  
Seismic Data ◽  
Broad Band ◽  
Computer Processing ◽  
Preliminary Evaluation ◽  
Digital Recording ◽  
Digital Form ◽  
Data Resource ◽  
Long Period ◽  
Period Data ◽  
Mass Position

abstract Thirteen advanced seismograph systems, called Seismic Research Observatories (SRO), are being installed as part of a program to upgrade the worldwide seismic data network. The SRO system was created by combining a recently developed broad-band borehole seismometer and a software-controlled recording system. The seismometers are being installed at a depth of 100 meters to avoid wind-generated noise in the long-period band. A seismometer output that is flat in acceleration between periods of 1 and 50 sec is used to produce both short- and long-period data that are recorded on analog drum recorders and in digital form on magnetic tape. Very-long-period data, obtained from the seismometer mass position output, can be recorded as well. Digital recording of gain-ranged data provides an amplitude of nearly 120 dB. Preliminary evaluation of the SRO data system indicates that major design objectives have been met. The network of SRO stations will be an important new data resource for seismological investigations, especially for those studies that require computer processing of the data.

Noise level variation at norsar and its effect on detectability

1977 ◽  
Vol 67 (2) ◽  
pp. 479-492 ◽  
Author(s):  
F. Ringdal ◽  
H. Bungum
Keyword(s):  
Atmospheric Pressure ◽  
Noise Level ◽  
Amplitude Distribution ◽  
P Wave ◽  
Seasonal Fluctuations ◽  
Long Period ◽  
Short Period ◽  
Noise Data ◽  
Band Pass ◽  
Period Data

Abstract For a 3-year period, noise level measurements of short- and long-period data at NORSAR have been sampled at hourly intervals. Significant seasonal fluctuations in noise level have been found, in particular for long-period data. The noise amplitude distribution is approximately lognormal for band-pass filtered short-period data in the P-wave detection band, while the long-period noise data show a skewness that cannot be represented by a lognormal distribution. Diurnal fluctuations in noise level are quite small, but definitely present both for short and horizontal component long-period data. Cultural sources are found to account for the short-period variability, while the long-period fluctuations are attributed to atmospheric pressure variation. Event detection performance generally follows the noise level trends, with an increase in the number of reported events during summer of about 50 per cent relative to winter.

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.

Definition and identification of seismic events in the USSR in 1971

1974 ◽  
Vol 64 (3-1) ◽  
pp. 607-636
Author(s):  
Ola Dahlman ◽  
Hans Israelson ◽  
Atle Austegard ◽  
Gunnel Hörnström
Keyword(s):  
Focal Depth ◽  
Seismic Monitoring ◽  
Seismic Events ◽  
Long Period ◽  
The Earth ◽  
Short Period ◽  
Complete Test ◽  
Period Data ◽  
Test Ban ◽  
Test Ban Treaty

abstract Seismic events reported to have occurred in the USSR in 1971 are studied to assess the seismic monitoring problem as it may occur in the context of a complete test-ban treaty. Available epicenter data of a total of 199 events, 180 earthquakes and 19 explosions, are presented. Focal depth estimates reported by the National Oceanic and Atmospheric Administration, U.S., and the Institute of Physics of the Earth, Moscow, are compared. Identification parameters determined using short- and long-period data from Hagfors Observatory and supplementary short-period data from the Yellowknife array station in Canada are presented. To study the combined operative efficiency and applicability of available identification parameters, the reported depth estimates and the identification data are assessed in a defined way.

Rebirth of a fallen leader: Italy and the long period data

1985 ◽  
Vol 13 (3) ◽  
pp. 12-26 ◽  
Author(s):  
William J. Baumol
Keyword(s):  
Long Period ◽  
Period Data

Very long-period data from the geoscope network: Preliminary results on great circle averages of fundamental and higher Rayleigh and Love modes

1984 ◽  
Vol 74 (6) ◽  
pp. 2221-2243
Author(s):  
G. Roult ◽  
B. Romanowicz
Keyword(s):  
Rayleigh Waves ◽  
Quality Factors ◽  
Preliminary Results ◽  
The Third ◽  
Long Period ◽  
Phase Velocities ◽  
Rayleigh And Love Waves ◽  
Period Data ◽  
Available Information ◽  
Large Earthquakes

Abstract We have analyzed the long-period Rayleigh and Love waves that were generated by four recent large earthquakes (New Ireland of 18 March 1983; Costa Rica of 4 April 1983; Honshu of 26 May 1983; and Chagos Islands of 30 November 1983). Our records are those of the three-component very long-period stations (SSB, PCR, PAF, and TAM) of the GEOSCOPE network, that were in operation in 1983. Available information from transverse and radial components is obtained; preliminary results concerning the fundamental modes of Love and Rayleigh waves, the first toroidal overtone, the second, and the third spheroidal higher mode are presented. For each of these particular modes, the phase velocities and sometimes the Q quality factors have been obtained, and the methods of data reduction are described in detail for future reference. The examples shown demonstrate, in particular, the benefits to be expected from a modern three-component very long-period network, as well as from original station locations.

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