sika not mixed properly ?
Was anyone hurt? Given the popularity of the route and the fact that it's a better choice at this time of year than other Yos. objectives it'd be amazing if nobody was up there!
"I am sure that one way or another it will get restored to climbable shape," said big-wall expert Dave Allfrey. "Maybe it is just a question of how many bolts it will take. It is wild because I was just up there on June 10, and we retreated after some pretty sizable rockfall came right off the Visor in the late evening, following a thunderstorm a few hours prior."Thank god this didn't happen that day—there were 14 people at the base," Allfrey added. "It really is amazing that nobody got hurt or killed. It could have been so bad."
Some of that was down to a team above hauling carelessly but during the night(s) we slept up there, there was constant rockfall and the final time we attempted it an alarmingly large block landed a little too close for comfort whilst tying on! This prompted us to leave it as it's just something completely beyond your control and seemed to be ever-present.
A guy I know did it recently and thought it was fine.
Apparently it was fine two weeks ago and not fine by the 5th July.
How far up and down does the power law relationship go?
What's the frequency of one micron diameter rockfalls?
No correlation I'm afraid. Rock fall magnitude/frequency follows a negative power law distribution (many small events - very few high ones) and over a reasonably long sample time (e.g a year to ten years) - is pretty random. It can of course be set off by earthquakes and during thaws (ice holding it together) but it's hard to pin it down or predict it in any way. In my best professorial terminology: shit happens.
Quote from: tomtom on July 07, 2015, 07:30:01 pmNo correlation I'm afraid. Rock fall magnitude/frequency follows a negative power law distribution (many small events - very few high ones) and over a reasonably long sample time (e.g a year to ten years) - is pretty random. It can of course be set off by earthquakes and during thaws (ice holding it together) but it's hard to pin it down or predict it in any way. In my best professorial terminology: shit happens.Not sure I completely buy that for all instances of rockfall - The one that Habrich references happened in an area where there is relatively little observed rockfall. In this case, the detachment of a large block was preceded by a few days of relatively high frequency smaller rockfall from around the same area - I find it very hard to believe that they weren't related.
Rock fall follows the same distribution to earthquakes and landslides. You get many many small ones, but only the odd large one. Like earthquakes there are only certain parts of the world where you are likely to have them (fault zones for earthquakes, cliffs for rockfalls - they can't happen on a plateau obviously..) but in those zones it would appear their size and frequency is largely unpredictable..
Quote from: tomtom on July 08, 2015, 06:02:24 amRock fall follows the same distribution to earthquakes and landslides. You get many many small ones, but only the odd large one. Like earthquakes there are only certain parts of the world where you are likely to have them (fault zones for earthquakes, cliffs for rockfalls - they can't happen on a plateau obviously..) but in those zones it would appear their size and frequency is largely unpredictable..The power law for earthquakes doesn't say anything about the relationship between when the small and larger frequency events occur though, just the relative frequency with which events of different magnitude are observed over a (long) period of time in relation to each other which doesn't seem to cover any spatio-temporal relationship?The power law says you get small events frequently and only sometimes are these related to larger events without small events being a necessary precursor to a large event but it wouldn't be unexpected for larger rockfalls (or earthquakes) to occasionally be preceded by a series of smaller events but the infrequency with which they coincide makes them a pretty poor predictor overall. It doesn't seem unreasonable to me though, that because of the phyiscal nature of rock that sometimes the two are related, but that all areas of rockfall are different and this is not therefore true across all strata.
Ahh.. you're being sucked in by the need to see cause and effect there slackers
Good points there. Still doesn't address the question, how often do you get a rock fall of 10 km diameter? Put that in your power law pipe
