Site Description, Operational History, and Broadband Noise Characteristics of IRIS/IDA Stations AAK (Ala-Archa, Kirghizia) and TLY (Talaya, Lake Baikal Region, Russia).

摘要

Averaged ambient ground noise power spectra are calculated for two broadband IRIS/IDA 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 IRIS/IDA 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 IRIS/IDA 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 IRIS/IDA stations in the USSR.