April 18 2007

New IDA station installed in Madagascar

IGPP's Project IDA extended the reach of the Global Seismographic Network into a new part of the world this week when IDA engineers placed the finishing touches on a seismic station in Madagascar. Staff members Christopher Sites and Charles Cazier traveled to Antananarivo, Madagascar, two weeks ago to install extremely sensitive seismometers at a site in the countryside outside the capital. This station is the forty-first opened by Project IDA. IDA scientists strive to deploy their sensors in as globally uniform a fashion as possible given the distribution of continents and islands. Several other teams at SIO are devising improved methods to operate similar instruments on the seafloor. By locating sensors over many regions of the globe, scientists may more accurately locate earthquakes and develop detailed models of the Earth's interior by measuring changes seismic waves undergo as they travel around the world.

The IDA station is hosted locally by the Institut & Observatoire Geophysique d'Anatananarivo (IOGA). The leader of the IOGA team, Dr. Gérard Rambalomanana, intends to use data collected at the station to contribute to his country's tsunami warning efforts. The tsunami that followed the 2005 Sumatra-Andaman Islands earthquake killed more than one-quarter million people in the Indian Ocean basin and left many others homeless. Nations bordering the Indian Ocean are working to create a warning system similar to one existing for the Pacific Ocean. Project IDA has sites on four other islands in the Indian Ocean: Sri Lanka, the Seychelles, Cocos (Keeling), and Diego Garcia. All were operating during the 2004 quake, and had a warning system been in place, these stations would have provided key technical data needed to save countless lives.

The central highlands of Madagascar are an ideal place to locate seismic recording equipment for several reasons. Noise from ocean waves beating against the coastline diminishes substantially at this distance from the coast, and there is very little traffic on the few roads that exist in the country's interior. The central highlands are also underlain at their core by formations of granite. Hard rock such as granite transmits seismic waves with little distortion so they may be recorded with high fidelity. Madagascar sits between two seismically active regions, the East African rift zone to the west and the southwest Indian ridge to the east, so there will be no shortage of earthquakes nearby to be detected. The sensitive instruments at this station will be able to detect moderate-sized earthquakes no matter where they occur around the world.

The network of seismometers operated by Project IDA (International Deployment of Accelerometers) is an element of the larger IRIS/USGS Global Seismographic Network and is supported by the Cecil and Ida Green Foundation for Earth Sciences and the US National Science Foundation. Project IDA, which has existed at UCSD since 1975, is directed by IGPP scientists Dr. Jonathan Berger and Dr. Peter Davis.

Figure Captions

Figure 1. Workers begin excavation of the subterranean vault used to house the sensitive seismometers.

Figure 2. The pier on which the seismometers will rest is carved out of granite by hand.

Figure 3. IDA engineer Chris Sites tours the sites of Antananarivo with Gérard Rambalomanana and IOGA staff.

Figure 4. View from the station in the hills west of Antananarivo.