Landslides caused by heavy rain wreaked havoc in Kerala on Thursday, killing seven people, including three children, in Kozhikode district. Unconfirmed reports said that 10 people were trapped in debris.

The incident occurred in Karinchola village in Kattippara gram panchayat, 40 km north of the district headquarters.

Heavy rain has brought life to a standstill in many parts of the state. On Friday, landslides blocked two roads that pass through the western ghats – the Iritty-Makkootta inter-state highway that connects Kerala and Karnataka, and the Thamarassery-Sultan Bathery highway.

With heavy rain expected to continue till Sunday, the State Disaster Management Authority has issued a red alert for six districts – Kasargod, Kannur, Kozhikode, Wayanad, Malappuram and Thrissur. These areas face the likelihood of both floods and landslides.

Landslide season

The landslide season in Kerala starts with the onset of the south-west monsoon every year. Landslides include debris flows, rock falls, rock slides and mud slips. Apart from claiming human lives, they destroy hills and vast tracts of agricultural land.

According to the disaster management plan published by the Kerala State Disaster Management Authority in 2016, as many as 295 persons have lost their lives in 85 major landslides in the state between 1961 and 2016. The most casualties were reported from the Amboori landslide in Thiruvananthapuram district on November 10, 2001, where 38 people died.

The document, which described the reasons for landslides and preventive measures that can be taken, stated that 14.4% or 5,607 sq km of the state’s total area is susceptible to landslides. Of Kerala’s 77 taluks or administrative divisions, the document said, 10 taluks are highly vulnerable to landslides, 25 taluks are in the moderately vulnerable category, and 14 taluks are the least vulnerable.

(Credit: Special arrangement).

Construction work to blame?

According to scientists, landslides occur when human intervention – such as building high rises, stone quarrying and the construction of roads – increases in landslide prone areas. They say prolonged and intense rainfall can trigger major landslides in these areas, and deforestation, obstruction of streams and cultivation of crops whose roots lack the capability to hold the soil together on slopes accelerates this process.

Geologist KG Thara, former faculty head at the Institute of Land and Disaster Management in Thiruvananthapuram, said those who promote unscientific development practices should be held accountable for landslides. “It is a major cause of concern that Kerala has been witnessing an increase in the number of landslides,” she said. “Construction of resorts and high rises has increased in landslide-prone areas. It is unscientific, and bureaucrats who grant permission for these projects should be held accountable for the loss of human lives and property.”

The 2016 disaster management plan also pointed fingers at construction work in landslide-prone zones. It recommended that all activities that trigger landslides should be regulated strictly.

(Credit: State Disaster Management Authority).

Effects of quarrying

Scientists say the use of explosives to blast through rocks in quarries is another important cause of landslides in Kerala. “Quarrying causes rapid landscape changes,” said TV Sajeev, a senior scientist at the Kerala Forest Research Institute. “It also blocks the natural hydrological pathways. This stress causes large rock bursts and hence landslides.”

In 2017, Sajeev mapped granite quarries in Kerala along with his colleague CJ Alex. This study identified 5,924 big, medium and small quarries in Kerala. With 867 quarries, Palakkad topped the list among districts, followed by Ernakulam with 774.

The study also assessed the proximity of quarries to earthquake epicentres. Between 1986 and 2013, Kerala witnessed 115 earthquakes measuring between 0.8 magnitude and 5 magnitude. The study found that 78 quarries lay within 1 km of the epicentre of the earthquakes.

Thara said quarrying and construction should not be allowed in landslide vulnerable areas. “I think Thursday’s landslide was caused by illegal construction of a rain pit on top of the hill,” she said. “A detailed inquiry will establish the reason.”

(Credit: Special arrangement).

How to avoid landslides?

Scientists believe that micro-level mapping of landslide prone areas and efficient disaster management system are the need of the hour.

A teacher with the Institute of Land and Disaster Management said on condition of anonymity that Kerala depends on the maps prepared by the National Centre for Earth Science Studies, also based in Kerala’s capital, to assess landslide-prone areas. “But the maps do not provide the actual location of the vulnerable zones as they are of high scale,” he said. “We need maps with small scale.”

Sajeev said that the National Centre for Earth Science Studies should share its maps with the public. “Let the people identify the landslide prone areas,” he said. “It will help authorities to communicate better with the people.”

He lamented the fact that Kerala only has a crisis management system at the moment. “That is why we act only after disaster strikes,” he said. “What we need is a disaster management to avert mishaps in future. It needs long-term planning.”