Communications – electrical: acoustic wave systems and devices – Seismic prospecting – Land-reflection type
Patent
1991-06-14
1993-05-25
Eldred, J. Woodrow
Communications, electrical: acoustic wave systems and devices
Seismic prospecting
Land-reflection type
367 38, 367 59, 367178, 181104, 181112, G01V 100
Patent
active
052146146
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This application is a national phase of PCT DE 90/00785 filed 15 Oct. 1990 and based in turn, of German application P 39 34 745.1 filed 18 Oct. 1989 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to a seismic directional sensor for solid-borne sound with at least one geophone with pronounced directional characteristic, whose electrical measuring vibration signals, which are obtained at different circumferential angular positions of its radial longitudinal axis, are to be compared with one another, are correlated with the direction of a seismic ray that extends at right angles to the longitudinal axis of the geophone and which is ineffective in its neutral circumferential angular position.
BACKGROUND OF THE INVENTION
The prior-art directional sensor is described in a textbook by E. F. Sawaransky and D. D. Kirnos: Elemente der Seismologie und Seismometrie (Elements of Seismology and Seismetry), pp. 339-344, published in 1960, hereinafter referred to as "Sawarensky and Kirnos" for short.
Directional sensors for solid-borne sound are especially needed in the low-frequency range below ca. 1000 Hz and in the infrasound range below ca. 25 Hz for locating artificial and natural seismic sources which are sites of any king of underground and above-ground extracting blastings, including the seismic prospecting of deposits and layer wave seismics, the seismics of pile drivers, machines and vehicles, earthquakes, rock bursts, gas explosions, and knocking signs of spills, as well as ground vibrations induced by sound transmitted by air.
The particularly important parameters for localization of a seismic focus are the azimuth alpha (a) and the emergence of surfacing angle epsilon (a) of the seismic ray at the site of observation.
Varying from the above-described state of the art of this class (Sawarensky and Kirnos), so-called arrays are currently preferably used in earthquake seismics (cf. H. P. Harjes and M. Henger; Array Seismology, published in Zeitschrift fur Geophysik, 1973, vol. 39, No. 6, pp. 865 ff., hereinafter referred to as "harjes and Henger" for short. Array seismology uses compound systems of seismometers arranged over an area, which are arranged in various configurations depending on their task, e.g., for locating near and remote earthquakes or for detecting or verifying nuclear explosions. Such configurations form can be an L-shaped, cross-shaped, triangular, or, more recently, even a circular arrangement see (publication of the Royal Norwegian Ministry of Foreign Affairs, NORSAR Norwegian Seismic Array "Seismological Verification of a Comprehensive Nuclear Test Ban", pp. 4-11).
Such arrays are expensive in every respect, especially because their extent may reach a few kilometers (small arrays) or several hundred kilometers (large arrays).
In array seismology, the determination of the azimuth of the seismic ray is based essentially on the measurement of the different arrival times of the wave at the individual seismometers. This procedure is called the "position correlation method" (cf. elsewhere in Harjes and Henger, pp. 880 ff., especially in connection with FIG. 7). Using digital measurements and filtration methods and special evaluation methods (beam forming), the angular accuracy of the azimuth alpha reaches .+-.5.degree. and at times up to .+-.3.degree..
The approach suggested by Sawarensky and Kirnos with the prior-art directional sensor of this class, which was described in the introduction, differs considerably from array seismology and the extremely expensive apparatus associated with it.
The prior-art directional sensor uses the azimuthal correlation. This measurement method consists of observing the phase and the amplitude of the seismic waves as a function of the azimuth alpha of the vibration direction of a plurality of horizontal seismometers at a measuring point. In contrast to the expensive array seismology, these horizontal seismometers are concentrated into a space with a transverse extent of a few
REFERENCES:
patent: 2406014 (1946-08-01), Harry
patent: 3573723 (1971-04-01), Michon
patent: 3803543 (1974-04-01), Cioccio
patent: 4300220 (1981-11-01), Goff et al.
patent: 4800981 (1989-01-01), Uttecht et al.
Aufsatz "Peilung von Bodenerschutterungen fur technische Anwendungen" Von Horst Kohler, Jena, aus Veroffentlichungen des Zentralinstituts fur Erdbebenforschung in Jena 1949, Heft 51, Seiten 6314 98.
Physica Verlag Wurzburg vol. 36, 1973 Article "Array-Seismologie".
Norsar Norwegian Seismic Array Seismological Verification of a Comprehensive Nuclear Test Ban.
Sawarenski and Kirnos "Elemente der Seismologie und Seismometrie".
Nobel Hefte Apr.-Sep. 1989 "Das Neue Schwingungsmessgerat der Wasagchemie".
Dubno Herbert
Eldred J. Woodrow
Kateshov Yuri
Wasagchemie Sythen Gesellschaft mit beschrankter Haftung
LandOfFree
Seismic directional sensor for solid-borne sound does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Seismic directional sensor for solid-borne sound, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seismic directional sensor for solid-borne sound will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-903134