Since our last visit to the Hunza valley, in northern Pakistan, the artificial lake caused by what many consider the largest landslide in recent times has grown to 13 km from 12 km and is now 221 feet deep, a rise of over twenty feet.

It is estimated that the water is rising by almost two feet per day, and may trigger a dam burst that would leave a trail of destruction downstream - all the way from lower Hunza to Gilgit, the provincial capital of the Northern Areas now known as Gilgit-Baltistan.

Some people are even warning that a dam burst could threaten the country's largest dam at Tarbela on the Indus river.

A huge landslide in the mid-1800's wreaked havoc all the way up to the Arabian Sea, washing away an entire Sikh Army station along the river banks.

Any dam burst would be catastrophic and army engineers are busy digging a channel that will release water from the new lake in a bid to prevent the water rising upstream.

If the dam goes, it could wash away over a dozen major bridges that form the crucial chain in the country's only road to China, known by many as the Karakorum Highway, or the KKH.

People in high-risk downstream villages under immediate threat have been asked to vacate the area and move in with host families in safe zones.

For populations further downstream, who would have nearly half an hour to escape the flood, an early warning siren system to alert all nearby villages to evacuate immediately has been arranged.

Evacuation drills have been conducted and exit routes identified.