Last week, torrential rainfall across Indonesia’s largest island, Sumatra, triggered flash floods and landslides, causing widespread destruction. Twenty people died earlier this week in four areas in North Sumatra province amid flash floods and landslides. On Thursday morning, another devastating landslide claimed seven more lives. This landslide struck the main access route between Medan, the provincial capital, and surrounding regions, burying vehicles – including a tourist bus – in mud, rocks and trees. More than 10 people were injured and rushed to the nearest hospital in Medan. Rescue efforts are continuing, with several vehicles still trapped in the debris. North Sumatra’s traffic director estimated it may take up to two days to evacuate those affected.
Flash floods and landslides are a frequent occurrence in Indonesia owing to seasonal rainfall from October to March, caused by the Asia-Australia monsoon circulation system. This phenomenon causes wind to blow from Asia to Australia, bringing increased water vapour and consequential rainfall to Indonesia. Teleconnections such as El Niño-Southern Oscillation can also influence rainfall patterns, with the likely upcoming La Niña phase expected to bring further extreme weather by the end of the year, intensifying the risk of flooding and landslides as sea surface temperatures in the Pacific Ocean drop below average and easterly trade winds strengthen, pushing additional moisture into the region.
