As much as 388.3 sq. km of land in Idukki district, comprising 8.9 per cent of the total area, is highly susceptible to landslips while 873.7 sq. km (20 per cent) is susceptible to a lesser degree.

Devikulam taluk has the largest area highly prone to landslips (177.8 sq.km), followed by Peerumedu (88.7 sq.km), Udumbanchola (69.8 sq.km) and Thodupuzha (52 sq.km), according to the multiple hazard zonation map for Idukki district. The map prepared by the Centre for Earth Science Studies in 2009 also identifies the flood prone areas in Idukki.

The hazard zonation maps highlighting the areas susceptible to landslips, floods, coastal erosion, storm surge, lightning and earthquake in each district were sent to the respective District Collectors as part of the pre-monsoon preparedness exercise undertaken by the Hazard Vulnerability and Risk Assessment (HVRA) Cell under the Department of Disaster Management.

The District Collectors in Idukki, Wayanad and Kozhikode were warned about the possibility of landslips occurring during the monsoon season. At a meeting convened by Revenue Secretary and Relief Commissioner T.J. Mathew in the last week of May, the administration in the three districts was asked to be prepared to take up relief activities in the event of landslips.

Earth scientists, however, feel the district-level maps would need further finetuning to be of use to the administration in preparing for disasters like the landslip that occurred at Cheeyappara in Idukki on Monday. N.P. Kurian, Director, CESS, said village- level micro-level hazard zonation maps on 1:12500 scale would be required.

John Mathai, scientist, CESS, who was Principal Investigator of the hazard zonation mapping project in 2009, said the district-level maps had to be followed up by an exercise in hazard vulnerability and risk assessment, considering the population in the hazard-prone areas and roads and critical installations, among other things. This, he said, should culminate in village- level maps highlighting the susceptibility of each survey plot. “It is a massive exercise, but one that has to be undertaken if disaster management and response is to improve”.

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