Massive rockfall - Waterfall route


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Big Mike

Trad climber
Dec 8, 2017 - 07:43am PT
Hi Greg, Thanks for all your work. I really enjoy learning about the cliffs where I like to hang.

Cool graph! How does lightning cause rockfall?
'Pass the Pitons' Pete

Big Wall climber
like Ontario, Canada, eh?
Feb 28, 2018 - 08:47pm PT
Well, f*ck me, it's good to still be alive!!
Mighty Hiker

Outside the Asylum
Apr 30, 2018 - 10:04pm PT
It will be interesting to see a photo of the rockfall area from the spring, once it dries out, to see what can be seen, also if there's been further rockfall there.

Trad climber
Ontario, Canada
May 1, 2018 - 07:25am PT
Hey Big Mike. Lightning is hot! It blows up trees by the rapid expansion of the moisture in the wood. I would think the same could apply to rocks...

Interesting graph but what's the difference between "unrecognized" and "unknown?" Does "unrecognized" mean the rockfall could be attributed to one or more of a number of factors?

Yosemite Valley
May 1, 2018 - 02:35pm PT
Lightning has been known to explode rocks on summits (and also melt them), so it's reasonable to think that it could trigger rockfalls. It hasn't happened very often in Yosemite though.

We can't measure rockfall triggering directly, so we make inferences based on the environmental conditions present at the time of the rockfall. For example, if a rockfall occurs coincident with an earthquake or an intense rainstorm then assigning a trigger if fairly easy.

"Unknown" means that we have no information on what the environmental conditions were at the time of the rockfall, so we cannot even speculate on a trigger. Most of the rockfalls in the database that have "unknown" triggers happened a long time ago and are based on very cryptic reports.

"Unrecognized" means that even though we do have good information on the environmental conditions at the time of the rockfall, there still isn't an obvious trigger. If a rockfall happens on a clear, mild day with no seismic activity, what is the trigger? We will say that it is "unrecognized", meaning that we really don't know.

As a scientist, "unrecognized" is the most interesting category because there is a lot to learn there.

Yosemite Valley
Jun 14, 2018 - 09:40am PT
For anyone interested, here is a short (and hopefully readable) paper on our analysis of last year's rockfalls from El Capitan. I find the sequence of rockfalls shown in Figure 2C especially fascinating.
looking sketchy there...

Social climber
Lassitude 33
Jun 14, 2018 - 10:02am PT
Thank you for posting the link to this very interesting and informative paper.

Trad climber
Jun 14, 2018 - 04:58pm PT
Anyone have a good photo of the "outward displacement" section?

Yosemite Valley
Jun 14, 2018 - 06:05pm PT

Social climber
Jun 14, 2018 - 09:54pm PT
hey there say, gstock... wow, neat... thanks for sharing... :)

Gym climber
Jun 14, 2018 - 10:21pm PT
The last slab to go was 8m thick... yikes!

Trad climber
Jun 14, 2018 - 11:54pm PT
Kinda makes me think of the nipple pitch and the white circle...

Clint Cummins

Trad climber
SF Bay area, CA
Jun 15, 2018 - 02:52am PT
Great work, Greg.
Thanks for sharing!

So important to make an informed decision to reopen the road,
as there is a very real risk of head-on collisions when the road is 2-way.

Jun 15, 2018 - 04:11am PT
Wow, the "going for location" folks must have that crack in their sights!

right here, right now
Jun 15, 2018 - 08:33am PT
Fascinating predictive capabilities now on tap, as described in GStock's recent PDF from the previous page:
The sheet is
bounded on three sides by rockfall scars,
and likely displaced during or immediately
after the 22 Oct. 2017 rockfall. This geometry,
combined with a simplified fracture
mechanics analysis, indicates that the sheet
should detach with another 20% of fracturing
along the partially attached side.
Although the 3-D data do not allow us to
predict exactly when this will occur, they
do define the precise location and volume
of this future rockfall.

Please excuse my ignorance of the current status, but does this mean the area is indefinitely closed, including walkoff to the West from the top of climbs such as Moratorium?
And approaches to the East Buttress and other routes to the east of the scar?
Mighty Hiker

Outside the Asylum
Aug 8, 2018 - 12:18pm PT
Three Yosemite National Park employees were honored on July 4th by Secretary of the Interior Ryan Zinke at the 73rd Honor Award Convocation Ceremony in Washington, D.C. Park Ranger Jesse McGahey, Park Ranger Philip N. Johnson, and Firefighter/Paramedic Nick Bliss received the Valor Award of the Department of the Interior for heroic actions, courage, and professionalism exhibited in the line of duty.

On September 27, 2017, the park received a 911 call of climbers injured in a catastrophic rockfall event originating from the South side of El Capitan. Due to a high potential of additional rockfall events off of El Capitan, Park Ranger McGahey was inserted to the scene of the injured parties via helicopter short haul and was the first Ranger and Park Medic on scene. One patient had been helped out of the zone of immediate danger from an additional rockfall. Ranger McGahey worked to stabilize and package the patient, who was suffering from life-threatening injuries.

(Although I'm curious as to why they call it a "rockfall event". By definition, a massive rockfall is an event.)

Aug 8, 2018 - 02:14pm PT
TFPU, Anders.

Congratulations to Jesse et al. I know ya didn't do it for the fame, JM, so double props : )
Mighty Hiker

Outside the Asylum
Aug 28, 2018 - 09:15pm PT
Well, on the subject of ranger/climbers being honoured:

You may encounter Valley District Ranger Jack Hoeflich directing traffic, patrolling Yosemite Valley via bicycle, taking ambulance calls, acting as Search and Rescue duty officer, performing a rescue on Half Dome, giving directions to a lost visitor, or mentoring a new ranger. He is a federal law enforcement officer, park medic, structural and wildland firefighter, technical rock rescue instructor, helicopter and swift water rescue technician, horse patroller, and more. In 2007, he received a valor award for a heroic actions while rescuing a gravely injured climber from the face of El Capitan. Other rangers look at him and wonder, “how is he so good at all that stuff?” For all this and more, Jack is the recipient of the 2017 Barry Hance Memorial Award.

The Barry Hance Memorial Award is a peer-nominated award that is named in honor of Barry Hance, a long-time employee of Yosemite National Park who died in an avalanche while plowing the Tioga Road in 1995. Recipients of this prestigious award are employees who exemplify the qualities and attributes of Barry Hance. These include teamwork, a positive attitude, concern for the public and fellow employees, public service, and a deep love for Yosemite National Park.

OK, this may not have anything directly to do with the events last September, but Jack is a great guy, plus helps at the Facelift every year.…/park-ranger-jack-hoeflich-receives-pr…
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