Analysis Results of the Level of Seismic Noises in the Frequency Range 1-15 Hz on the Bottom of the Black Sea at Depths to 1000 M (Rezultaty Otsenki Urovnya Seismicheskikh Shumov V Diapazone Chastot 1-15 Gts NA Dne Chernogo Morya NA Glubinakh Do 1000 M).

摘要

An analysis of seismic noise in the 1 to 15-cps range recorded in 1963 on the bottom of the Black Sea at depths of 300, 500, and 1000 m is presented along with a description of an ocean-bottom seismometer. The frequency-amplitude characteristic of the instrument package provides undistorted seismic-signal reception over the 0.06-- to 1-sec period range. The signals are recorded on magnetic tape at slow speed and played back at high speed, thus permitting a significant increase in the data storage capacity of the unit (about 4 days). The results of the spectral analysis of noise at the stated depths are given, with wind force and sea surface conditions taken into account. The noise spectra obtained (amplitude versus period) show a decrease in noise intensity with depth. It is also seen that each spectral function (shown graphically) consists of two part differing sharply in intensity. For the 0.06 to 0.6-sec range, the noise level is comparatively low, while above 0.6 sec, the noise level shows a sharp increase. Tabular data presented in the article show that at depths of 300 to 500 m, the noise level in the 0.06 to 0.6-sec range compares to that at the most seismically quiet continental points. (Author)