Volcanoes true height?

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Haliku

 
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Re: Volcanoes true height?

by Haliku » Sat Nov 22, 2003 12:48 am

Having grown up on NGS magazines I'll take their word for it. Hard to stay in business for 100+ years if you're giving out false information. Thanks Tex.
"What doesn't kill you makes you stronger." --Friedrich Nietzsche

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climber21

 
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Re: Volcanoes true height?

by climber21 » Tue Nov 25, 2003 7:41 pm

Thanks for the info. It's good to know. I thought i saw that in one of their magazines a couple years back. Anyway, it looks like i am going home (to Mexico) for Christmas, and if there is time, my dad and i are hoping to do a trip to Orizaba. Might see some of you up there. =-)

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climber21

 
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Re: Volcanoes true height?

by climber21 » Mon Oct 11, 2004 1:02 am

Ya, i've seen some very differing accounts for the mountains' heights. Even in one magazine advertizing the state of Puebla, they had Spanish on the left and English on the right. They put down at least somewhat accurate meter measurments for the volcanoes under the Spanish section; but for the English section they simply calculated by 3 the meters to get feet, making a meter exactly three feet. Obviously that didn't work.

On more accurate maps, i've seen most political maps seem to say Orizaba is somewhere around 18,400'. An aeronautic map, about 15 years old, puts it at 18,701. But, as Texas Climber showed that National Geographic recently put it at 18,854.99. Perhaps i am biased in wanting it to be as tall as they'll put it; but National Geographic is also quite reputable when it comes to this sort of thing. =-)

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bc44caesar

 
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Re: Volcanoes true height?

by bc44caesar » Mon Dec 06, 2004 8:49 pm

So why isn't this correct height updated on the SP Orizaba page?

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rickford

 
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Re: Volcanoes true height?

by rickford » Fri Jan 21, 2005 1:13 am

National Geographic has the summit measured at 18,900. I recently climbed Orizaba yet forgot to record the altitude on my GPS. People who climbed at the same time as me- which was during high barometric pressure maintained that the mountain is around 18,600. Not sure.....

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Haliku

 
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Re: Volcanoes true height?

by Haliku » Sun Jan 23, 2005 2:04 am

I was up there two days ago and the GPS was reading 18,450. Its a borrowed gps so I´m not certain to the altitude accuracy. The mystery continues...
"What doesn't kill you makes you stronger." --Friedrich Nietzsche

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Jonathan de Ferranti

 
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Re: Volcanoes true height?

by Jonathan de Ferranti » Sat Feb 26, 2005 1:35 am

This looks authoritative, from an article by a GPS specialist:

http://www.utsa.edu/pub/sombrilla/pdfs/summer2003.pdf

From Page 23:

"We took 1200 GPS atitude samples while on the summit and calculated Orizaba's height to be 18490.5 feet..... (5636m).

Jonathan de Ferranti

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Haliku

 
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Re: Volcanoes true height?

by Haliku » Wed Mar 09, 2005 8:24 pm

I've been in contact with the professor of the article posted above. His confidence level on the altitude reading is 95% +/- 50 feet. He wasn't able to calibrate the readings with a fixed base station as there wasn't one close enough in the region. Otherwise the +/- variance would be smaller.
"What doesn't kill you makes you stronger." --Friedrich Nietzsche

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Haliku

 
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Re: Volcanoes true height?

by Haliku » Thu Oct 13, 2005 4:20 am

Pearson - I won't even pretend to understand what you posted in the second half. Pertains to SRTM then? Let us all know if you find anything on Orizaba and SRTM. Cheers!
"What doesn't kill you makes you stronger." --Friedrich Nietzsche

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RModelli

 
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Re: Volcanoes true height?

by RModelli » Sun Oct 16, 2005 7:18 am

Climber21...
that was good about the argentinians..not many people here would understand that joke...
I am Brazilian.

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viewfinder

 
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Re: Volcanoes true height?

by viewfinder » Tue Dec 06, 2005 5:40 pm

Hello Pearson,

You can download SRTM data from <A href=ftp://e0srp01u.ecs.nasa.gov/srtm/version2/>here</A>.

But unfortunately for Orizaba it is of limited use, because the cells that fall in or around the summit crater are void. Form SRTM the 5747m elevation given above by the National Geographic Society, can be ruled out, but nothing accurate can be determined. I would trust the 18490ft ± 50ft (5636m ± 15m) elevation and accuracies given by the professor.

I have uploaded more information about Mexico's highest volcanoes <A href=http://www.sol.co.uk/v/viewfinder/elevmisquotes.html#mexico>here</A>. I have also uploaded local SRTM data.

There is plenty of evidence that competent GPS readings and SRTM data disprove the many given summit elevations that are hundreds of feet lower, or, more frequently, higher.

Competent optical readings are usually accurate too, but if they are taken from a distance in conditions of abnoramal refraction, then large errors are possible. But a more common cause of elevation inaccuracy is deliberate politically or commercially motivated exaggeration.

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