A cloudburst on the night of August 6 could have set off the deadly landslide in Pettimudi in Kerala’s Idukki district which claimed nearly 70 lives of tea plantation workers and their families, said a top official.
Cloudburst is the phenomenon by which a particular geographical area receives copious amounts of sudden rainfall in a short period of time.
Speaking to the Indian Express on the causes behind the landslide, Prem Krishnan, the sub-collector in-charge of Devikulam taluk that encompasses Pettimudi, said, “A preliminary investigation is going on with the help of geologists. On August 12, forest officials had gone up to the site believed to be the origin of the landslide. They are saying a major landslip has taken place there. A lot of debris snowballed and came down.”
“I think a cloudburst may have taken place because I was looking at the rainfall data. On Aug 5, 31 cm rainfall was recorded. On Aug 6, 62 cms of rainfall was recorded, double the previous day’s amount. It was raining non-stop on Aug 4, 5 and 6. It was the same in Munnar. We never thought it (Pettimudi) was a susceptible zone. So a landslip would have taken place and debris flow is seen as the initial reason, accompanied by heavy rain.”
Locals in Pettimudi have also attested to witnessing non-stop rain for almost four days leading up to the night of August 6 around 11 pm when a river of slush and debris flowed down the side of a hill, burying four rows of living quarters of the workers. Due to incessant downpour, power and communication lines were snapped in the region, leading to news of the landslide reaching the outside world only by next day morning, thus delaying government rescue operations. A key bridge linking Rajamala, where Pettimudi is located, to Munnar town was also destroyed in the rain.
As of Sunday, 58 bodies were recovered from the rubble, leaving 12 more missing. Twelve people were rescued in the initial hours of the tragedy.
According to rainfall statistics put out by Pradeep John, a popular weather blogger from Tamil Nadu, the Pettimudi station received 1842.7 mm (184 cms) rainfall from August 2-7, the highest rainfall in that period in Idukki district. On August 7 alone, the region got 616.2 mm rainfall in a 24-hour period, the same morning the landslide was reported. This was reportedly the heaviest rainfall in that region in four decades. In fact, the four-day rainfall record in Pettimudi this year, he said, could be the second-highest 96-hours event of all time in Kerala, after the big deluge in 1924.
The sub-collector said the tragedy in a region that was believed to be relatively safe by authorities further spurs the need for re-creating a hazard vulnerability map for the district of Idukki.
Rekha Nambiar, the NDRF commanding officer who heads the search and rescue operations in Pettimudi, said the reasons for the landslide are possibly geological and hydrological.
“This is a highly stable region. The landslide itself has originated almost five kilometres away. If you see the photographs, it’s probably 200 metres wide at its widest, but has run almost five kilometres in length…(there could have been) a huge accumulation of water and once it starts, it’s like an avalanche. It carries its own dirt and earth material. That adds to the momentum and as it comes down, it washes away all the trees in the path. It adds to the destruction as it goes. This (Pettimudi) was the end-point. Unfortunately, all the accumulated material has been deposited here.”
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