Kuwait National Seismic Network

The Design of the Kuwait National Seismic Network

The KNSN was designed with and provided with the most up-to-date international techniques in the field of seismography. It consists of eight permanent seismic field stations distributed all over Kuwait according to the tectonic setting of the State. Seven of these stations are short-period stations. The eighth station is a very broad-band station. Each station has mainly 3 parts. The first part is the observatory unit, which includes three seismometers (SS-1 Ranger seismometer) in the short period stations or one seismometer (Streckeisen STS-2 seismometer) in the very broad band station. Seismometers are placed on a solid, leveled surface in a 3 to 4 meter deep seismic vault (cylindrical room) to record the ground motion in three dimensions: one vertical direction and two horizontal directions (i.e., north-south and east-west).

The second part is the recording and digitizing unit to amplify, digitize and record the observed data. Refraction Technology 72A-07 data acquisition system (DAS) is used for recording and digitizing the observed signals. DAS has three channels 24-bit digitizer/recorder and internal RAM that provides a 512K buffer for data retention, allowing adequate storage for packets to be retransmitted. The third unit is the communication unit that includes transmitter (T45F-2), receiver (R45F) and antenna as a full duplex unit fixed on a communication tower erected at each station. The Monitron model T45F-2 is a narrow-band transmitter with frequencies selectable in the 381 - 391 MHz band. The radiated power is maximum 4 W. The Monitron model R45F is the matching receiver in the 381 - 391 MHz band. The antenna employed is Yagi Antenna with 12dB gain. The antenna is mounted vertically polarized to minimize interference. Accordingly, Kuwait National Seismic Network is a real-time telemetric full duplex seismic network. The stations are powered by batteries, which are charged through solar cells to supply continuous power. Siemens Pro4 JF solar electric module has 36 specially processed single crystal solar cells that are capable of producing 75 watts at over 4 amps. Two Solar Panels with two 220 Amp-hour batteries provide adequate power. There is a charge controller to prevent the batteries from being overcharged.

Each seismometer converts the earths vibrations into an electrical potential that is proportional to the amplitude of these vibrations. The voltage is digitized in the field into a digital value with precise sampling signals by the DAS. The generated digits are assembled into 1024 bytes packets (encoded data) and are continuously sent through a full duplex modem board by radio communication to the recording/analysis center at KISR. When the event trigger actuates, a flag is sent with a data. The modem encoding is QAM (Quadrature Amplitude Modulation) which allows 9600 baud transmission. The full duplex modem participates in the error-detection and correction process and also the retraining process. This setup enables KNSN to record all local seismic events and most of regional and distant seismic events.

In addition to the permanent stations, there are 6 portable stations. Each portable station consists of an advanced 6 channel broad-band, high resolution recording/digitizing seismic system (Quanterra Q330), three seismometers (SS-1) and 3-components accelerometer (Episensor) to record the acceleration of the earth under earthquake effect. Each Quanterra Q330 includes 8Mb RAM, GPS receiver for Universal Time signals, power management, sensor command/control, and an advanced telemetry application for reliable data delivery. The recorded data are stored in an external storage unit called Quanterra Packet Baler (PB14F) that is connected directly to Q330 via IP network technology. PB14F is a modular, field-ready high-capacity recording system that stores up to 20 GB of ready-to-use data in internationally-standardized Federation of Digital Seismic Networks MSEED format. The data are retrieved from PB14F and Q330 by using portable computer that has special software for field stations operation. Portable stations are powered by batteries that are recharged by solar cells.

The Current Seismic Stations
Devices to monitor earthquakes
Recorder/Digitizer of Portable Station

Last revised March 2009

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