Why did the IMD get its seismic record wrong - scaling down Wednesday night's quake intensity to 4.2 Richter from its initial 6.6?

When the quake struck the capital and its suburbs at around 11.30 p.m. the Indian Meteorological Department officials in Safdarjung Enclave in south Delhi were frantically trying to get in touch with their counterparts in Delhi University area who man the seismic department office. But the phones lines were busy.