Question

waste water pumped down disused tubewells reduce the extent of destruction caused by earthquakes-give reason

Answer 1

The waste water pumped down disused tube wells can reduce the extent of destruction caused by earthquakes by preventing the pressure applied on the underlying rocks by the water that seeps underground. The seeped water triggers the earthquake by the lubricating the fault.

Answer 2

As the water trickles underground it applies pressure on the underlying rock & provides lubrication to the fault  thereby triggering an earthquake or increasing its intensity. Hence waste water should be pumped down to reduce the extent of destruction caused by earthquakes.