General Information on IMS Infrasound Station IS52, Diego Garcia

Background

Infrasound array IS52 is located on the island of Diego Garcia, in the Chagos Archipelago in the British Indian Ocean Territory, south of India. The station consists of seven MB2000 microbarometers arranged in concentric triangles with a common center element.

Figure 1. Location map of the island of Diego Garcia.

The heavily vegetated island has an area of 6,720 acres. The average elevation is four feet above sea level. The maximum elevation is 22 feet. This island is horseshoe shaped with a perimeter of approximately 40 miles. Diego Garcia is a living coral atoll; the coral reefs and island are made up of trillions of living organisms. Once an ancient volcano, all that is left is the atoll surrounding a central lagoon. Thanks to its tropical location and heavy rainfall (about 100 inches per year), the island is heavily vegetated with coconut palm and ironwood trees. Wildlife on the island consists mainly of coconut, land, and warrior crabs (Figure 2); small lizards and geckos; a variety of tropical birds and many insects.

Figure 2. Coconut crab in a coconut tree.

Array Information

IS39 is a seven-element array deployed in a triangular geometry with four elements in central cluster. The baseline of the array is approximately 2 km. The infrasound data is collected at 20 hz, while the meteorologic data is recorded at 1 hz.

Each element consists of one MB-2000 pressure sensor, a Geotech DR-24 digitizer, power regulation and surge suppression electronics, and a GPS timing system. These items are housed in a fiberglass enclosure supported and protected by a heavy-duty aluminum framework. The enclosures are elevated above ground to prevent flooding and are designed to be corrosion and UV resistant and strong enough to withstand falling trees.

Due to its extremely remote location, there is little cultural noise at IS52. Notable signals that have been recorded at this station include the December 26, 2004 tsunami in Aceh, Indonesia.