The devastating 2024 Wayanad landslide cannot be attributed to extreme rainfall alone but was also likely influenced by a combination of geological, geomorphological and structural factors, according to a new study published in the international peer-reviewed journal Landslides .
Evidence and Data
The study, published online on the journal’s website, notes that while intense monsoon rain triggered the collapse, underlying geological conditions played a critical role in determining where the landslide began, how it travelled, and why it became one of the most destructive landslides recorded in the Western Ghats. The study was conducted by researchers from the University of Kerala, the Indian Institute of Science Education and Research (IISER) Mohali, and Savitribai Phule Pune University. It carried enormous quantities of rock, soil and vegetation, causing widespread destruction. The study suggests that the landslide originated within a highly weathered shear zone near the crown, where a first-order stream crossed the weakened rock. During the extreme rainfall, water rapidly infiltrated the interconnected fractures, increasing water pressure within the slope. Once the strength of the rock mass was exceeded, a large block detached, initiating the landslide. “The study reveals the interplay of climate and geology. Anilkumar and K.S. Sajinkumar, assistant professors at the Department of Geology, University of Kerala, who led the study.
The disaster struck on the night of July 30, 2024, when exceptionally heavy rainfall of nearly 573 mm within 48 hours triggered a massive slope failure in the upper catchment of the Punnapuzha river. It rapidly evolved into a high-speed debris flow that travelled nearly 8 km, descending about 768 metres while sweeping through Punchirimattam, Mundakkai and Chooralmala.
Extreme rainfall acted as the immediate trigger, but the pre-existing geological framework determined where the slope failed, how the debris moved and why the event became exceptionally destructive,” said Y.
