Monday 29 August 2022

Landslide kills family of five in Kerala State, India.

Five members of a family have died after a landslide swept their house away in Kerala State, India, on Monday 29 August 2022. The incident happened in the village of Kudayathoor, in Idukki District, at about 4.15 am local time, following heavy rains overnight associated with the seasonal monsoon. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.  

Rescue workers recover the body of a woman who died when a landslide struck her family home in the village of Kudayathoor in Kerala State, India, on 29 August 2022. Reju Arnold/On Manorama.

The deceased have been identified as homeowner Chittadichaalil Soman, his mother Thankamma (74), his wife Shiji, their daughter Shima (25), and her son Devanand (4), with all the bodies recovered within five hours of the original incident. The area is still thought to be unstable, presenting a risk to nearby households, and local authorities are assessing the need to evacuate the entire community.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Kerala has a complex seasonal cycle, driven by the presence of the Western Ghats mountain range, which largely block the dry northerly winds which dominate the climate of much of India, and its proximity to the equator, which leads to a double monsoon system. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest. In Kerala this results in a Southwest Monsoon, which lasts from May to September, and is driven by winds from the southern Arabian Sea dumping water onto the Western Ghats, followed by a Northwest Monsoon, which lasts from October to December, where winds from the Bay of Bengal do the same. Of the two monsoons, the southwest is the wetter, due to the proximity of the sea, with June typically being the wettest month, with an average of 341 mm of rain falling in the month

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