What Nepal's floods reveal about “cascading hazards”

The Nepal disaster appears to be a “cascading event,” where one hazard seems to have triggered another, experts say

A catastrophic flash flood has struck northern Nepal on the Tibetan border, killing at least 157 people and leaving hundreds missing, including at least 34 Australians . The death toll is expected to rise.

Foreign tourists are among those feared dead or missing. Nepal’s tourism ministry reported 403 tourists unaccounted for, including 341 foreign nationals .

Footage shows torrents of mud and debris sweeping through settlements and carrying buildings and vehicles with them.

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Early evidence suggests this was not an ordinary rain-driven flash flood, but what disaster science describes as a “cascading event”. So what do we know so far?

Investigators are examining a chain of events high in the Himalayas where one natural hazard seems to have triggered another.

Such phenomena are known as “cascading hazards”—chain reactions where an initial event directly triggers a sequence of subsequent events, often creating a much larger disaster.