The 21 February 2005, catastrophic waste avalanche at Leuwigajah dumpsite, Bandung, Indonesia

International audienceOn 21 February 2005 the Leuwigajah dumpsite, Bandung (Java, Indonesia) was affected by a largeslide after heavy rainfalls. Second deadliest waste slide in history, it buried 71 houses and killed 143 people.Amongst the contemporary disastrous events of this type, only a few have been documented. We explored failurepreconditions, triggering mechanisms and local context that conducted to this disaster. We carried on four fieldinvestigations on the site. A series of aerial photographs were acquired and completed by topographical measureson the ground. The morphology of the slide and its trajectory were reconstructed. To constrain the movementcondition, we studied the internal structure of the source area and realized surveys among stakeholders of thedumpsite and citizen.Results: 2.7 10 6 m3 of waste materials spread 1000 m from the source in a rice field with an average thickness of10 m. The material displays a preferential fabric parallel to the previous topography. Numerous internal slip surfaces,underlined by plastic bags explain the low friction coefficient. The presence of methane within the waste dumpwas responsible for explosions prior to sliding and for the fire that affects whole sliding mass.Conclusions: Resulting of a combination of heavy rainfall and consecutive explosions due to biogas suddenrelease, this disaster was predictable in reason ofi) a front slope of the dump of about 100% before the failure;ii) a poor dumpsite management;iii) the extreme vulnerability of the marginalized scavengers living at risk at the foot of the instable dump