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Rock Slide off Half Dome
Posted: Mon Mar 30, 2009 7:57 am
by copeg
I was camped at the top of the Snow Creek trail along the rim of Yosemite Valley on friday night, and all night long I could hear the cracks of snow avalanches in Tenaya Canyon. Around 5 in the morning I was awoken by a thunderous crack, following by a rumble that echoed through the valley. Groggy, I thought to myself "what the heck was that", then fell back asleep. The following morning I didn't notice a thing.
Coming back down yesterday I stopped at the same place and looked across the valley, noticing a washed out line along the lower side of Half Dome. Talking to some folks camped nearby, they recounted their night in Curry Village as they woke to the crack, rumble, and shaking thinking Glacier Point had let loose and they were gonners. Fortunately the slide happened at a time of day that no one was below, because who knows what could have happened if this occurred in the middle of the day. The slide closed the south part of the Mirror Lake trail, and the north side was covered in an inch of granite dust, clouds of which were blown up with the slightest gust of wind making it difficult to breath at times.
This image was taken about half way up the Snow Creek trail.
Re: Rock Slide off Half Dome
Posted: Mon Mar 30, 2009 9:21 am
by The Other Tom
WoW ! Glad no one was hurt.
Re: Rock Slide off Half Dome
Posted: Mon Mar 30, 2009 12:16 pm
by copeg
The Other Tom wrote:WoW ! Glad no one was hurt.
Me too.
From the
Yosemite Daily Report:
New Today
Ahwiyah Point rock fall - A very large rock fall occurred from Ahwiyah Point near Half Dome at 5:26 am on the morning of March 28. The rock fall originated near the summit of Ahwiyah Point and fell roughly 1800 feet to the floor of Tenaya Canyon, striking ledges along the way. Debris extended well out into Tenaya Canyon, knocking down hundreds of trees and burying the southern portion of the Mirror Lake loop trail. Reminiscent of the 1996 Happy Isles rock fall, there appears to have been a small airblast associated with impact on the valley floor. Fortunately, due to the event occurring in the early morning, there were no injuries. The impact generated ground shaking that was recorded by numerous seismometers across California, registering as the equivalent of a local magnitude 2.5 earthquake. The volume of the Ahwiyah Point rock fall is still being determined, but it was clearly one of the largest rock falls in the past decade; for perspective this rock fall was many times the size of the recent October 2008 rock falls behind Curry Village. Numerous smaller rock falls have occurred from Ahwiyah Point since the initial failure, and the southern portion of the Mirror Lake loop trail remains closed until further notice. (G. Stock - 3/30/09)
Re: Rock Slide off Half Dome
Posted: Mon Mar 30, 2009 12:48 pm
by Snow Nymph
The Other Tom wrote:WoW ! Glad no one was hurt.
Yeah! glad no one was hurt! I remember hearing rockfall by Toe Lake a few years ago, couldn't sleep that night.
Re: Rock Slide off Half Dome
Posted: Mon Mar 30, 2009 4:48 pm
by gdurkee
Very impressive. I was there Friday but left in the afternoon. Would have liked to have seen -- from a safe distance -- the slide. I was at Curry Village and kept thinking how unsafe that whole area seemed (though, of course, that's not anywhere near the rock slide talked about here).
Here's a link to another photo & story:
http://climbing.about.com/b/2009/03/30/ ... f-dome.htm
http://www.supertopo.com/rockclimbing/g ... glgral&n=1
g.
Re: Rock Slide off Half Dome
Posted: Tue Mar 31, 2009 4:15 pm
by giantbrookie
Snow Nymph wrote:Yeah! glad no one was hurt! I remember hearing rockfall by Toe Lake a few years ago, couldn't sleep that night.
Interesting. In 1986 I was fortunate to witness the biggest rockfall I've seen in my hiking days at Toe Lake. It was on talus slope on the other side of the lake, so it was more of a spectator sport than a terror. It was at night and the racket drove me out of the tent to watch. It was quite a sight, what with all the sparks and such.
That Half Dome rockfall is quite impressive. We (Fresno State geo department) have a grad student working on a research project on rockfall hazard in Yosemite Valley with Greg Stock. This will certainly be of interest to her.