Geologists assess Yosemite hotel rockfall risk

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Majid_S

Mountain climber
Bay Area
Topic Author's Original Post - Aug 28, 2009 - 01:50am PT
By TRACIE CONE (AP) – 6 hours ago

YOSEMITE NATIONAL PARK — Scientists worked Thursday to determine if a boulder avalanche that forced the closure of a landmark Yosemite lodge was a one-time event or a precursor of more rockslides to come.

The Ahwahnee Hotel remained closed following a series of landslides Wednesday that peppered the storied building's parking lot with boulders — one the size of two SUVs.

There were no injuries but three cars were damaged and the area was covered in a thick layer of gray dust, after the rocks tumbled from Royal Arches, a popular climbing route that towers 1,600 feet above the majestic retreat.

The hotel's 300 guests were immediately evacuated but escorted back to their rooms Wednesday night to collect their belongings, before being put up in hotels outside the park.

"We realize now that the first one may not be the only one. We want to err on the side of safety," said park spokeswoman Kari Cobb.

A park geologist has been studying the stability of the granite face cut by glaciers and erosion to resemble the arches for which it was named, hoping to determine by Friday afternoon if the hotel can reopen or if the avalanche was a prelude to other rockfalls.

"Yosemite is a wild place," Cobb said.

Park scientists say rockfalls seem to have accelerated in recent years and are the most significant force affecting the Yosemite Valley — a spectacular natural wonder that receives more than 3 million visitors a year.

Since 1857, at least 535 rockfalls have killed 14 people and injured 62, more than at any other national park. Only in the last few years has the park hired a full-time geologist to assess risk.

Still the park was caught off guard last year when rocks hit 17 cabins in Curry Village and sent 150 youngsters running for their lives. A month later park officials permanently closed the 233 cabins closest to the base of Glacier Point.

Park policy is to treat rockfalls as part of a potentially larger series of events.

"We know now that we can never predict rockfall," said Cobb. "We can only learn from what we've done in the past and move forward. Even though some visitors will be upset, we can only say that safety is our No. 1 concern."
nature

climber
Tucson, AZ
Aug 28, 2009 - 01:55am PT
if locker could see to read he'd respond...




























YER GONNA DIE!!!111666



sorry, was that bad?


Thanks for the post. It'll be interesting to watch how the accelerated mass wasting plays itself out.
jfailing

Trad climber
A trailer park in the Sierras
Aug 28, 2009 - 04:08am PT
Greg Stock, geologist Superman of the Valley, to the rescue!
Patrick Sawyer

climber
Originally California now Ireland
Aug 28, 2009 - 04:45am PT
Only in the last few years has the park hired a full-time geologist to assess risk.


Seems a bit surprising that a full-time geologist for such work is relatively new to the park.
luggi

Trad climber
from the backseat of Jake& Elwood Blues car
Aug 28, 2009 - 11:26am PT
climb now nature...the loose stuff is already down...
Srbphoto

Trad climber
Kennewick wa
Aug 28, 2009 - 11:51am PT
Let me guess...We are going to spend thousands of dollars for a scientist to tell us "yes, there will be more rockfall in Yosemite!" I'll get up in front of the press for a sheep and a six pack and tell them today!
jstan

climber
Aug 28, 2009 - 01:30pm PT
"Park scientists say rockfalls seem to have accelerated in recent years"

We have heard speculations on this before. It would appear, from the above, there is some data supporting it. Greg is an important resource and here on ST we have seen what he brings to the Park.

Props.
Gunkie

climber
East Coast US
Aug 28, 2009 - 01:35pm PT
I just don't want to be on or under the 'Ear' or 'El Cap Spire' when they cut loose.
Toker Villain

Big Wall climber
Toquerville, Utah
Aug 28, 2009 - 01:46pm PT
I'm just imagining the coyote chimneying Texas Flake with his Acme suction booties when it cuts loose,..






Uh,.. Gee,.. a ditch thousands of feet deep AND THERE'S ROCKFALL???
Do tell.
(they don't really need a geologist unless he/she is exceptionally good gazing into a crystal ball.)

Hundreds of recorded rockfalls and barely more than a dozen dead in a crowded valley?
Lucky SOBs I'd say.


(But its Kalifornia; maybe they need a helmet law,..)
JesseM

Social climber
Yosemite
Aug 28, 2009 - 08:11pm PT
I've been up around Virgina Peak, Return Lake while all of this has been going on. Now I'm on my way to Boulder, CO. I still haven't heard anything from Greg Stock...the only person I'd really trust to report something comprehensible about the rockfall this. I'll encourage him to post here when I talk to him.

Jesse

Yosemite Climbing Ranger
saa

Social climber
SF Bay Area
Aug 28, 2009 - 08:46pm PT
Jesse, Greg,

Greg had some decades of data posted on this forum (I think) about 8 months or a year ago. Has the report been written? If yes, could you post a link to it?

Thx
Mighty Hiker

Social climber
Vancouver, B.C.
Aug 28, 2009 - 09:01pm PT
Greg's post to a thread last autumn:

You can download an Excel file of documented rockfalls in Yosemite from 1857 to 2004 here: http://pubs.usgs.gov/of/2003/of03-491/

I have documented all observed rockfalls since 2004, and was originally planning to include them in an updated USGS Open-File Report to be published in 2010. However, given the keen interest in these data I may try to make them available sooner.
M_LaRiviere

Trad climber
Oakland, CA
Aug 28, 2009 - 10:59pm PT
Hi -
I was on the South Face of Leaning Tower on Monday & Tuesday this week. While walking back to our cars in the hotel lot late Tuesday (actually super early Wednesday a.m.), my partner and I heard the thunder / rifle cracks of light (?) rock fall coming from the Royal Arches area. In retrospect, those sounds were probably precursors to the rock fall that hit the parking lot. Is there a number that should be called to report if/when rock fall is observed?
(This was actually the second fall I've been seen this season... I was on the Nose early on the morning of July 3rd and saw fall on the other side of the valley, somewhere left of the Middle Cathedral)
- M.
neebee

Social climber
calif/texas
Aug 28, 2009 - 11:15pm PT
hey there say, thanks for the share...

has the awannee ever been closed before, due to rock fall... i was just curious...

i know that lynda works there... will it stay closed for a while now?...

yep,i did hear about the camp closures before, though....

i was just trying to keep up on the situation...
glad no hikers were hurt...
god bless... take care all...
camm-it-up

Trad climber
Los Angeles, CA
Aug 29, 2009 - 11:04am PT
aww bummer, rich folks can't get their spa treatments in the valley anymore.
nature

climber
Tucson, AZ
Aug 29, 2009 - 11:21am PT
This isn't about the rock fall itself. This is about risk assessment. Do geologist look into crystal balls? Yeah. Do they see anything? No. But this is like with any specialty - if you don't know it well you probably don't understand the nuances. We don't need Greg to tell us if there will be more rock fall. We need him to do an analysis on the situation, do some number crunching, and develop a statistical model of the chances of another huge rock fall before we (they) can allow joe public to re-enter the area.

Data seems to suggest there is an increase in rockfall. Greg will look into that and tell us. But at the end of the day it's a bunch of numbers. And sadly, especially in environmental sciences like geology, your intuition and gut feeling is probably what's correct. But big brother wants crunched numbers and they don't always add up and make sense.
Tony Bird

climber
Northridge, CA
Aug 29, 2009 - 12:01pm PT
most rockclimbers have some hands-on ability to assess the soundness of rock, perhaps as much as your average geologist. i'm with the guy who said that, after the rockfall, that spot is safe now. do they even know the exact spot these ahwahnee rocks came from? if it was a loose, texas flake-type formation, it should be obvious that that danger is past. the rest is a crapshoot--absolutely unpredictable. a "perched" piece of rock could go tomorrow or 50,000 years from now.

i think it's important to know what you don't know, and i don't see that here. rather, they're trying to promulgate the myth that they're in control and taking care of the public. there may be some room for advancing the science of exfoliatory mechanics--not sure it's worth the effort--but i don't see much sophistication yet. can this greg fellow give us a prediction on texas flake? boot flake? the dozens of rim boulders like the one skinner and piana once belayed off? i doubt it. the best advice is to avoid areas of known rockfall--keeler couloir comes to mind--and take your chances elsewhere. i still love to climb on glacier point--occasionally.
Dr.Sprock

Boulder climber
Sprocketville
Aug 29, 2009 - 12:15pm PT
thats john muir pushin those rocks down on the capitalist pig intruders!

yo John!
Gunksgoer

Trad climber
nj
Aug 29, 2009 - 01:23pm PT
Seems like there should be a pretty obvious scar where the rock came from. A sweep of the surrounding cliff area seems like the responsible thing to do and would provide the most reliable answer.
NewtMan

Trad climber
Redondo Beach, CA
Aug 29, 2009 - 02:31pm PT
Sitting at the Curry Village taco bar wednesday, we heard what sounded like thunder and a huge cloud of dust just to the left of the Arches. Two more followed within a few minutes. So glad to hear nobody was hurt. With the forest fire smoking up the valley a day later, it was an "unusual" week in the valley, to be sure! Still got some nice climbing in on the Apron and Open Books, but definitely makes one stop and think...
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