History of Huaraz

After the 1941 disaster the old reservoir dam was repaired but not replaced. Doubts about the safety of the dam were largely responsible for abandonment of that area for redevelopment. The creek valley upstream from the city in the mid-1960s exhibited scarred inner banks several meters higher than the normal water level. The scarring caused by the avalanche was increasingly higher above the stream bed on the creek valley walls nearer the reservoir. The scoured appearance of the creek valley indicated the mass and power of the avalanche gaining momentum as it crashed down the narrow valley, accumulating debris as it descended.

By 1965 fewer than a half dozen buildings had been rebuilt in the creek valley adjacent north of the city. The valley was still filled by as many as three meters of soil and debris deposited by the 1941 avalanche. Giant boulders lay about, some protruding as many as four meters above the 1965 creek bed level. Many boulders from the 1941 avalanche were strewn down to the confluence of the creek with the Rio Santa. Huaraz area residents who remembered the disaster of 1941 said in 1965 that the river itself was diverted by avalanche debris for some days until eroded away and carried downstream (northward), and there were boulders on the west bank that had come with the avalanche.

On 31 May 1970 the same reservoir dam burst during the Ancash earthquake. 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