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Site Description, Operational History, and Broadband Noise Characteristics of IRIS/IDA Stations AAK (Ala-Archa, Kirghizia) and TLY (Talaya, Lake Baikal Region, Russia)
Semiannual technical rept. 1 Jul-31 Dec 1991,
SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA INST OF GEOPHYSICS AND PLANETARY PHYSICS
Pagination or Media Count:
Averaged ambient ground noise power spectra are calculated for two broadband IRISIDA seismic stations deployed at Talaya TLY near Lake Baikal in Russia and Ala-Archa AAK near Bishkek in Kirghizia, central Asia. Site descriptions are provided for these stations, as well as major episodes up to mid-1991 in their operational history that are relevant to potential data users. Findings can be summarized as follows AAK shows among the lowest average absolute nighttime noise levels above 1 Hz documented to date for IRISIDA stations in the former USSR its night-averaged noise levels above 1 Hz are very similar to those observed at GAR. Ground noise increases during the day at AAK, with the maximum increase 7-9 dB occurring between 2-3 Hz. Below .7 Hz, day and night noise at AAK is the same. TLY average nighttime noise level are about 6-10 dB higher than AAK levels above 1 Hz its night-average noise above 1 Hz is very similar to that observed at IRISIDA station KIV. Below .6 Hz, nighttime levels at AAK and TLY are comparable, except that TLY has lower horizontal noise levels 4-5 dB at periods longer than 25 s. Almost no difference between night and day noise was observed at TLY in this sense it is unique among IRISIDA stations in the USSR.
APPROVED FOR PUBLIC RELEASE