Predicting earthquake!
L-R: DEMETER satellite, How earthquake happens
Demeter stands for Detection of Electromagnetic Emission Transmitted from Earthquake Region. It is the first satellite for monitoring earthquake from space. It was launched on June 29, 2004 by a rocket from Baikanour. Researchers from many countries have been participating in this study. It is a micro satellite of 130 kilogram placed at an altitude of around 700 kilometres from the earth surface. It makes about 14 rotations around the earth per day. A set of instruments are deployed on the satellite. They are: electric sensor, magnetic sensor, plasma probes, and energetic particle detectors. The DEMETER Science Mission Centre is located at Orleáns, France. Earthquakes are usually caused when rock underground suddenly breaks along a fault. This causes sudden release of energy in the form of seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other they don't just slide smoothly but they catch on each other. The rocks are still pushing against each other. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs. During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicenter of the earthquake. It is observed that before a massive earthquake low frequency electromagnetic emissions are produced due to micro-fracturing process of rocks. This fact had been tested experimentally in Russia and in other countries. The emitted low frequency radiation goes to the ionosphere and perturb the plasma (ionized gas) there. The instruments in DEMETER record the low frequency noise in the region of epicentre of an earthquake. Intense theoretical and observational studies are being done at present to find the correlation between the earthquake emission and the plasma noise. In BRAC University at the Department of Mathematics and Natural Sciences, the DEMETER data are being analyzed and theoretical investigations on interaction of earthquake emission with the ionospheric plasma are being carried out which are published in international journals.
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