A woman has been killed by a landslide in the Chandmari District of Guwahati, in Assam State, India, on Wednesday 20 July 2016. Malati Das was killed when her home was engulfed by a mudslide following a period of heavy rain. 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. She was the sixth person killed by a landslide in Guwahati this month. A separate landslide in the Noonmati District destroyed a further two homes on the same day, though nobody was hurt in that incident.
Rescue workers at the site of the 20 July 2016 Chandmari landslide. Press Trust of India.
Guwahati is notoriously prone to landslides, particularly during the summer monsoon season, in part due to the hilly nature of the city, but largely due to the largely unplanned nature of many of the cities poorer districts, with many dwellings erected illegally without any formal planing permission, often on slopes where a thin layer of laterite clay covers a friable, sandy soil, which is prone to collapsing downslope when disturbed.
Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.
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.
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