Cliff face breaks off near climbers - GIF

[Altair]

Cliff face breaks off near climbers.



Previously:

Crane tips over while lifting bulldozer - GIF
Cliff collapses into lake - GIF
Reinforcing a cliff face - GIF
Excavator suspended from vertical hillside - photo
Rockslide destroys bridge - GIF

[Frank S]

Not only near them but between them. I wonder if one of them had used the crevices to set their pitons in order to belay themselves sideways in search of an accent path, which may have contributed to causing it to fall

[Bony]

One reason not to climb on quarry sites, although that location wasn't. That would certainly tighten several sphincters for me!

[hemmjo]

That is a thought provoking event.

It seems to take about 12 seconds for those rocks to make splash down into the water. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time they will have fallen around 450 m (1,500 ft). This is not quite the same since the rocks were rolling down part of the way. They were way up there.

[mklotz]

That is a thought provoking event.

It seems to take about 12 seconds for those rocks to make splash down into the water. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time they will have fallen around 450 m (1,500 ft). This is not quite the same since the rocks were rolling down part of the way. They were way up there.

In free fall in a vacuum, we have...

d = 0.5 * g * t² = distance fallen in time t seconds under influence of gravity g = 32 ft / sec²

so, for t = 12 sec.

d = 16 * 144 = 2304 ft

This is an upper limit on the height from which they fell. Effects like rolling, air drag, etc. will decrease this height but we don't have any data to calculate those effects. For something dense like rock, drag is probably a small effect; rolling, who knows?

[Saltfever]

Using the video timeline, or a stop watch, the time is about 14 seconds. The rock had just separated when the video starts so using that as a starting point the smallest rocks hit the water 14 seconds later. Adding 2 seconds gives a height of 3,100 ft and a terminal velocity of about 307 mph (450ft/sec). As Marv indicated density affects velocity in air. While a sky diver is usually 125-150 mph those rocks infer a greater height due to their speed.

[mwmkravchenko]

While they are high up, I'd say less than a thousand feet up. The size of the road would be a thin line at 3000 plus feet. The timing of the rock fall is both tumbling and friction so a free fall calculation is kind of moot. Still would scare the crap out of me. Life's short enough than to take unnecessary chances like this.

[Fluffle-Valve]

They're so luck to not be on the bit that fell.