Multi-Parameter Geophysical Observatory: gateway to integrated earthquake precursory research

To study earthquake precursors in an integrated manner, India's first Multi-Parameter Geophysical Observatory (MPGO) has been established at Ghuttu, Central Himalaya. The MPGO is located in a narrow belt of high seismicity where the colliding Indian–Asian plates are locked and are accumulating...

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Bibliographic Details
Published in:Current science (Bangalore) 2012-12, Vol.103 (11), p.1286-1299
Main Authors: Arora, B. R., Rawat, Gautam, Kumar, Naresh, Choubey, V. M.
Format: Article
Language:English
Subjects:
Density
Dynamics
Earthquake design
Earthquake prediction
Earthquakes
GENERAL ARTICLE
Geophysical observatories
Gravimeters
Gravitational fields
Groundwater
Groundwater level
Hydrology
Magnetic fields
Observational research
Observatories
Precursors
Radon
Rain
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Summary:To study earthquake precursors in an integrated manner, India's first Multi-Parameter Geophysical Observatory (MPGO) has been established at Ghuttu, Central Himalaya. The MPGO is located in a narrow belt of high seismicity where the colliding Indian–Asian plates are locked and are accumulating strains for future great earthquakes. The observatory is equipped with a superconducting gravimeter, overhauser and fluxgate magnetometers, ULF band search coil magnetometer, GPS, radon and water-level recorders. Supplemented by the dense network of broadband seismometers, the MPGO is designed to record precursory signals resulting from stress-induced changes in density, magnetization, resistivity, seismic wave velocity, fracture propagation, crustal deformation, electromagnetic and radon gas emission as well as fluctuations in hydrological parameters. The immediate priority for the characterization of precursory signals is to develop techniques to estimate and eliminate the background variation caused by the hydrological, environmental and solar terrestrial dynamics related changes. A careful scrutiny of the data associated with the Kharsali earthquake (ML = 4.9) of 22 July 2007, revealed unambiguous co-seismic gravity jump perhaps related to the change in volumetric strain. Similarly, radon fluxes show some definite trend that can be viewed as pre- and co-seismic changes related with the Kharsali earthquake. Sudden drop of geomagnetic field intensity and dynamic waveform, lasting from several days before to a week after the earthquake, appears to be a manifestation of the thermal agitation on the magnetization of rocks around the source region of the earthquake. A new method of location of seismo-EM source has been developed and its efficacy demonstrated in the seismically active Koyna region. The results obtained so far show that the multi-parameter approach crafted by the Ministry of Earth Sciences under the National Program on Earthquake Precursors holds promise and long-term monitoring needs to be continued for statistical validation.
ISSN:0011-3891