The exact timeline of the recent Nepal flooding disaster is becoming clearer. At 8:37am, instruments recorded what was initially interpreted as an earthquake near Nepal’s border with China. Seven minutes later, CCTV recorded the Gyirong Port border post being destroyed by a massive debris flow and flood.

Nepal’s flood authorities learned about the incident at about 9:00am and sent out an emergency SMS alert at about 9:15am. But by that time, Nepal was already deep into a major disaster.

The 38 minute gap between the tremor being detected and the emergency alert is striking. But it would be wrong to assume Nepal’s authorities could simply have acted on the initial signal: at the time, it appeared to be a small earthquake, rather than a much rarer mountain collapse. The flood also arrived too swiftly for water-level sensors: they went almost immediately from recording normal levels to being destroyed.

The more interesting question is what a better-integrated warning system might have made possible. Could seismic readings, satellite images and other observations have been combined quickly enough to recognise what was happening and alert people further downstream?

Existing early-warning systems have often been designed around particular hazards such........

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