Hyderabad: Earth beneath your feet is moving

Hyderabad: The land surface of Hyderabad could be increasing and decreasing depending on annual rainfall and the groundwater table.
Scientists say that the city land surface has been compressed and expanded on a periodic basis by as much as 2 to 4 centimetre and such deformities in the land mass could even change the latitude and longitude readings of a location on the GPS.

Though deformations could occur anywhere, the amount of rainfall would decide how much the compression would be. Of the two locations, Bengaluru and Hyderabad, that scientists analysed, Hyder-abad had a higher deformity.

Researchers from city-based National Geophysical Research Institute (NGRI) say that such deformations in the land mass should be factored into predictions of earthquakes. The deformation caused in landmass due to hydrological processes was analysed.

“People might not know but surface of Hyderabad is getting deformed like an elastic material,” Dr V.M. Tiwari, principal scientist, NGRI, said.
Locations were studied by Dr Tiwari, Mr N. Srinivas and Mr B. Singh by analysing data from GPS and GRACE satellites.

Scientists explained that rainfall and groundwater storage, termed as Total Water Storage (TWS), caused the landmass to get compressed like an elastic material due to pressure.

Once the water table goes down at the end of the rainy season and in summer, the landmass regains its original shape. The whole deformity could be as much as 2 to 4 centimetre in just a single year. Deformation in Bengaluru, however, was only about 1 to 2 centimeter, according to scientists.

Scientists say this has a larger impact on earthquakes and their prediction. “This also has to be factored in while predicting earthquakes and in tectonics. For instance, if there is plate and there is vertical force at the end of the plate due to high TWS and increased force, it could bend the plate. That will cause minor earthquakes. This is why you keep hearing about minor earthquakes in places close to Nagarjuna Sagar,” Dr Tiwari explained.

Hyderabad has a strong surface but such deformities in the surface would have repercussions in areas where there are fault lines like Coastal Andhra.