On 31 May 1970 the same reservoir dam burst during the Ancash earthquake, which had a moment magnitude of 7.9 and a maximum Mercalli intensity of VIII (Severe). Down the creek valley, again came an avalanche, eerily similar to that of 1941. In the prior four years or so, the suburb had begun to again be redeveloped: numerous residences were built atop the 1941 avalanche deposit within the at-risk creek valley. Within its duration of 45 seconds, virtually every structure of consequence in the city's center was destroyed. A few minutes later, the north half of the city, particularly in the creek valley, was obliterated by an avalanche of icy mud carrying boulders and other debris.