Mt Whitney Webcam
Mt Williamson Webcam
Who's Online Now
0 members (), 121 guests, and 3 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Page 3 of 3 1 2 3
Re: 14,508: Mt Whitney Elevation
saltydog #41412 01/16/15 12:31 PM
Joined: Jun 2011
Posts: 18
Offline
Joined: Jun 2011
Posts: 18
This reminds me of a conversation I had with a colleague years back, who was working in geomapping, with some very sensitive GPS equipment. She shared a shocking fact with me, that any given point on the earth's crust, is flexing up and down on a daily basis, mostly due to tidal forces - (sun and moon gravitational forces, and also in response to ocean tides). Depending on what the ground is made of, local faults, etc, it can be as much as a few centimeters. Most geological survey data doesn't take this into account, except as a "margin of error" baked-in to permanent measurements.

Re: 14,508: Mt Whitney Elevation
dethMarch #41439 01/18/15 03:19 PM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
This is really interesting stuff, DethMarch. Its like our planet is breathing with tides. Did you perhaps mean millimeters per day instead of centimeters? I didn't realize the earth's surface fluctuated vertically so much.

Surveying for vertical control is based on leveling back to the previous benchmark, which is within eyesight, so both points move up or down about the same amount. So the fluctuations you're describing are not detectable between points close together using standard survey methods. GPS, based on satellite measurements with a global perspective can measure the up and down movement of both points, or any point for that matter.

GPS has allowed measurement of uplift of mountain ranges, fault slip, and tectonic drift. One way this is used is in predicting the probability of an earthquake on a particular fault. The chance of an earthquake occurring is based on an average annual "slip." The horizontal movement builds up stress over the years, and then lets go suddenly.

The most active reaches of the San Andreas fault move horizontally about an inch per year, and when it lets go, it can offset up to 30 feet near the epicenter. Here's a paper describing how they measure the slip rate with GPS.

Here's a paper comparing a leveling survey network with GPS measurements in Poland.

Edited for more detail and to add another link.

Last edited by SierraNevada; 01/19/15 08:58 AM.
Re: 14,508: Mt Whitney Elevation
SierraNevada #41612 01/27/15 05:21 PM
Joined: Jun 2011
Posts: 18
Offline
Joined: Jun 2011
Posts: 18
In most places, millimeters. In *some* places, centimeters. (was my understanding).

Some of that also has to do with tides bringing water into the water table (and back out) on a daily basis, which causes expansion and contraction as well. I think Whitney would more likely be millimeters. Because; granite.

I should write a grant proposal to get funding to bring one of those fancy $10,000 GPS receivers up there, to collect data for a few days. Not that that would settle any arguments. laugh

Last edited by dethMarch; 01/27/15 05:21 PM.
Re: 14,508: Mt Whitney Elevation
dethMarch #41616 01/27/15 09:36 PM
Joined: Sep 2009
Posts: 8,505
Likes: 103
S
Offline
S
Joined: Sep 2009
Posts: 8,505
Likes: 103
> I should write a grant proposal to get funding to bring one of those fancy $10,000 GPS receivers up there, to collect data for a few days.

DO IT! You will get help from the hiking community!

Re: 14,508: Mt Whitney Elevation
Steve C #53724 06/28/18 12:33 PM
Joined: Sep 2009
Posts: 8,505
Likes: 103
S
Offline
S
Joined: Sep 2009
Posts: 8,505
Likes: 103
Updating this thread... Just curious to see whether anything has been updated or changed.

NGS (National Geodetic Survey) has an updated "Survey Marks and Data Sheets" web page, with links to an interactive map: NGS Data Explorer

Using the explorer map and zooming in on Mt Whitney, we can find the highest elevation data sheet: PID : GT1809

That Data Sheet shows the elevation of 14508.

Re: 14,508: Mt Whitney Elevation
Steve C #53741 06/30/18 04:44 PM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
14,508 ft is only 0.021% higher than 14.505 ft, relative to sea level, which is the hikers perspective. By surveying standards, this is a HUGE discrepancy over the relatively short horizontal distance involved. So what government agency is going to overcome the logistical and funding challenges to get the world a reasonable answer? Will a private company step up? Does anybody really care?

Re: 14,508: Mt Whitney Elevation
SierraNevada #53743 06/30/18 05:45 PM
Joined: Sep 2009
Posts: 8,505
Likes: 103
S
Offline
S
Joined: Sep 2009
Posts: 8,505
Likes: 103
As you're well aware, SN, there is a much worse and more pressing problem lying all over the Whitney Zone, and we've been waiting and hoping a government agency would "overcome the logistical and funding challenges to get the world a reasonable answer... Does anybody really care?"

We sure do care, but I'm not sure about the others.

Re: 14,508: Mt Whitney Elevation
Steve C #53747 07/01/18 09:17 AM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
Steve, I can only guess what problem is lying all over the Whitney Zone. Does it come in a plastic bag and smell like crap? Its peak season, and I'm sure people will start bringing it up again. There's a new technological breakthrough ( toilet tech ) that seems to be working well under similar conditions as Whitney. There's reason for hope.

Last edited by SierraNevada; 07/01/18 12:40 PM.
Re: 14,505 or 14,508 -- Mt Whitney Elevation?
AxeMan #53787 07/04/18 08:46 PM
Joined: Jan 2018
Posts: 5
E
Offline
E
Joined: Jan 2018
Posts: 5
In world system it is ONE METER. How cares?

Re: 14,505 or 14,508 -- Mt Whitney Elevation?
Eugen #53799 07/05/18 10:40 PM
Joined: Sep 2012
Posts: 6
S
Offline
S
Joined: Sep 2012
Posts: 6
I've been communicating with the NGS Geodetic Advisor for the SW Region about this topic over the Spring and hope to discuss with him next week during a conference we will both be attending.

He has provided a lot of history and info on why there are so many published elevations, it is clearly a topic he is both professionally and personally interested in. In summary he makes two points:

- 14,500 ft is the most "defensible" value for Mt. Whitney using current benchmarks and datums, but the highest point of the peak is likely higher

- there will be new datums in 2022 so the references for both lat/long and elevation will be changing - Whitney and other elevations will be decreasing by (estimated) a little under 3 feet

I'll report back if I learn more.

Last edited by skiroc; 07/05/18 10:42 PM.
Re: 14,505 or 14,508 -- Mt Whitney Elevation?
skiroc.xx #53809 07/08/18 07:46 PM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
The should sell t-shirts and other swag with velcro numbers to keep up with these changes.

Re: 14,505 or 14,508 -- Mt Whitney Elevation?
SierraNevada #53847 07/11/18 10:40 AM
Joined: Apr 2014
Posts: 26
Likes: 2
C
Offline
C
Joined: Apr 2014
Posts: 26
Likes: 2
What I love most about this whole elevation debate is the 1930 NPS plaque installed by someone lacking an understanding of significant figures: "14,496.811 Ft". That's an implied precision of ±0.3 millimeters, or the size of a small grain of sand. laugh

Also waiting for some sufficiently large group of burly DIYers to stack, upend, or reorient any of the most prominent boulders just to mess with people. What constitutes the "summit" of a loose rockpile?

Re: 14,505 or 14,508 -- Mt Whitney Elevation?
cantare #57079 05/22/20 08:55 AM
Joined: Sep 2009
Posts: 8,505
Likes: 103
S
Offline
S
Joined: Sep 2009
Posts: 8,505
Likes: 103
It appears that Mt. Whitney may be losing a foot or two pretty soon.

Article, NY Times: The U.S. Is Getting Shorter, as Mapmakers Race to Keep Up
Link: "height modernization"

Re: 14,505 or 14,508 -- Mt Whitney Elevation?
Steve C #57084 05/22/20 04:59 PM
Joined: Sep 2011
Posts: 1,158
Offline
Joined: Sep 2011
Posts: 1,158
The Rockies are going to lose a little more than Whitney with these adjustments. The Ranger is not going to like that, Yogi. Not as many 14ers there.

Page 3 of 3 1 2 3

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.4
(Release build 20200307)
Responsive Width:

PHP: 7.4.33 Page Time: 0.045s Queries: 43 (0.039s) Memory: 0.6479 MB (Peak: 0.7648 MB) Data Comp: Off Server Time: 2024-03-28 12:45:54 UTC
Valid HTML 5 and Valid CSS