About NNC RK Observation System.

Seismic array AS057-Borovoye.

Seismic array As057-Borovoye is one of the auxiliary stations of the International Monitoring system, created by PTS CTBTO.

AS057-Borovoye seismic array is situated in Schuchinsk district of Akmola region of Republic of Kazakhstan near Vorobyevka settlement. The central facility is situated 8 km to the southeast from "Borovoye" geophysical observatory and 9 km south southeast from Borovoye resort settlement, which is situated by Borovoye lake (figure 1). Paved road connects the seismic array and "Borovoye" geophysical observatory and Borovoye settlement. Schuchinsk town is situated 16-18 km to the southwest from the array. AS057 IMS seismic array is situated on the territory of "Burabai" National Park in the pine forest. The surface relief where the seismic array is located contains hills of different height formed mostly by granites.

AS057 seismic array is located within Borovoye granite massif (figure 2). This massif refers to granite intrusions of silur- low Devonian age. The site is located in eastern peripheral part of the massif. The granites of Borovoye granite massif at the site are represented by medium- and coarse-grained poorly disseminated biotite - hornblend phase one granites (g1S1-D1). These granites are most popular in the region and have light gray and pink gray color. Numerous dykes of aplites and pegmatites can be seen at the site.

The containing rocks are Archean rocks (ARzr): mica schist, gneiss, amphiboles, marble limestones, and Proterozoic rocks (PR1kk): sericite quartzite, cericite-chlorite-quartzide schists and dolomites. In the place of contact with granites these rocks turn into hornfels.

Intrusive granite massif and containing rocks are covered with quaternary sediments cover (QII-III - QIII-IV). These sediments are represented by silt loams sand clays with granite gravel, shingle, sands and clays.

Figures 1 and 3 show the locations of array elements (configuration) of As057-Borovoye seismic array. Coordinates of array elements, distance to the central element and depth of equipment boreholes are listed in table 1.

AS057-Borovoye seismic array consists of 10 elements with borehole seismometers. Short period one-component (vertical) seismometers GS21 and broadband 3-component seismometer CMG-3TB are used. One-component are located in the boreholes at elements A1-A4, B5-B9, and a three-component seismometer is located in a borehole at A0 element.

AS057 facility started operating on July 15, 2002. The system was certified in December 2002. Since then BVAR system (AS057) became a part of the International Monitoring System as an auxiliary station.

The system is equipped with 24-bit DAS. Sample rate equals 40 Hz.

All the data are accumulated, processed and sent to the subscribers by equipment, installed at the technical site. System units have individual IP addresses, allowing connecting to them remotely from a local network.

Digital data from the remote points goes through optic fiber communication channels. The data are bound to the world time with very good precision (down to milliseconds). Data exchange goes in full duplex mode. Seismic data can be acquired both in real-time and by request from a ring buffer whose capacity is 40 days. (Capacity of the memory of the equipment at the remote points is 30 hours).

Equipment forming data files to be sent to the International Data Center (Vienna) both by request (standard mode) and in real-time mode is installed at the technical site (see figure 4). There also is a hardware-software complex, allowing to receive all the data at "Borovoye" observatory. The system is integrated into Data Center local network via satellite communication channels.

Table 1. Coordinates of equipment boreholes and technical site of AS057-Borovoye seismic array.

Figure 4 - Equipment installed at AS057-Borovoye seismic array. Field equipment is marked in green Equipment at the technical site is shown in blue Part of the AS057 system equipment located in Borovoye observatory is marked in brown