Groundwater depletion behind Nepal earthquake?

Photo: NYT

Photo: NYT  

Major Himalayan earthquakes influenced by extensive irrigation activity in the Indo-Gangetic Plain, say scientists

Extensive groundwater extraction in the Indo-Gangetic Plain over the last five decades has significantly contributed to the killer April 25, 2015, Nepal temblor and “probably all earthquakes” in the region beneath the Himalayan arc, Indian scientists claim.

Researchers at NIT Rourkela; CSIR-National Geophysical Research Institute, Hyderabad; and National Centre for Seismology (NCS), Ministry of Earth Sciences, New Delhi, have gathered evidence of the far-reaching consequences of human actions: how groundwater depletion can “advance the clock” of temblors occurring in the Main Himalayan Thrust (MHT), under the Himalayan arc where earthquakes originate.

“Plate tectonics is the prime driving force behind earthquakes but in the past decade there is a new trend of research. The focus is also on surface and sub-surface activities such as underground mining, fluid injection and reservoir construction due to hydropower projects as possible contributing factors to seismic activity,” Bhaskar Kundu of the Department of Earth and Atmospheric Sciences, NIT Rourkela, told IANS.

Earlier it was considered that small magnitude earthquakes are influenced by the seasonal loading and unloading (removal process of groundwater) of the Indo-Gangetic Plain in summer and winter, said NCS director Vineet Gahalaut, one of the authors of the study.

“We have shown that great and major Himalayan earthquakes are influenced by the anthropogenic groundwater unloading process in the Indo-Gangetic Plain, which is probably the most intensely irrigated region in Southeast Asia,” Gahalaut said.

Comprising about 250 million hectares of fertile land (most of northern and eastern part of India) the Indo-Gangetic Plain is the most populated region of India, Pakistan, and Bangladesh.

It is also home to 40 percent of India’s population. Population density is highest in eastern Uttar Pradesh and Bihar in India and northern Bangladesh, leading to very high irrigation activities.

“Around seven percent of this process (anthropogenic ground water depletion) has contributed to advancement of the clock, that is, the timing of the earthquakes. The saturation level for stress is attained early due to depletion of groundwater. This is quite significant,” Kundu pointed out.PTI

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