Japan earthquake/tsunami effects on Geocaching

[+thecaswellfamily]

Disclaimer: I am not an extremely technical person, but I know that many of you are and will hopefully be able to satisfy my curiousity.

 

CNN reported that the earth is now spinning a little bit faster after the big subduction zone earthquake in Japan... also that Japan has "moved" as much as 8 feet in at least one place and the earth has shifted on it's axis link to article. My question is, will this affect our GPSrs in any significant fashion? How will this affect the satelites in their orbit (don't they read from ground locations?)? Granted, we are not geocaching in Japan (I assume the Japan maps will be off right now- or will they?), but will there be any difference worldwide?

 

I'm also wondering if rescuers rushing into the area will be able to use GPS technology... I think that is pretty standard, so will their stuff still work?

 

P.S. Still looking for an article on the spinning faster bit- saw that comment live on CNN last night.

[+StarBrand]

The axis shift is a small minor one (except for the fact that it involved the whole planet!!!) and should not affect things much.

 

The 8 foot shift of the whole island of Japan will obviously shift all caches by 8 feet as well. Well inside of average GPS error - so probably not a big deal.

 

I read a month or so ago about how the entire North American plate moves 3 inches or so to the WSW each and every year. Thus shifting all caches in the USA that much each year. 10 year old caches have moved 30 inches since placement. Furthermore smaller fault zones move as much as 10" per year across the country in varying directions. Caches in those areas have moved a staggering 100 inches in 10 years!!!

[+mpilchfamily]

It all eventually evens out. While the North American plate and Eurasian plates are colliding in the Pacific they are spreading apart in the Atlantic. Like StarBrand said it grows 3 inches a year. All the plates are growing at some places and crashing into each other at others. Overall the planet size stays ruffly the same. So the spinning of the earth isn't affected much.

 

As i recall from science class the earth is slowing and moving closer to the sun while at the same time the moon is moving further from the earth.

 

It would take 50+ years before plate tectonics cause a cache to drift so far off that it would have to be relocated or position updated. Well i suppose a good 9.0 in the right spot could move a section of the earth enough to warrent the update. But at that point the cache would probably be lost as well as a good chunk of the human population around the area.

[+thecaswellfamily]

The axis shift is a small minor one (except for the fact that it involved the whole planet!!!) and should not affect things much.

 

The 8 foot shift of the whole island of Japan will obviously shift all caches by 8 feet as well. Well inside of average GPS error - so probably not a big deal.

 

I read a month or so ago about how the entire North American plate moves 3 inches or so to the WSW each and every year. Thus shifting all caches in the USA that much each year. 10 year old caches have moved 30 inches since placement. Furthermore smaller fault zones move as much as 10" per year across the country in varying directions. Caches in those areas have moved a staggering 100 inches in 10 years!!!

 

Oh wow! Now that I think about it... I remember reading one time about things along a fault line in California that had moved over time... was that a thread in here? I remember seeing a photo of a fence line that was WAY out of line, LOL! Fascinating...

[+Gitchee-Gummee]

Disclaimer: I am not an extremely technical person, but I know that many of you are and will hopefully be able to satisfy my curiousity.

<snip>

My question is, will this affect our GPSrs in any significant fashion? How will this affect the satelites in their orbit (don't they read from ground locations?)? Granted, we are not geocaching in Japan (I assume the Japan maps will be off right now- or will they?), but will there be any difference worldwide?

 

I'm also wondering if rescuers rushing into the area will be able to use GPS technology... I think that is pretty standard, so will their stuff still work?

<snip>

 

Actually, no! The GPSr will not be affected as the coords will still be the coords. The fact that Japan has shifted as well as everything placed thereon doesn't affect the GPS (the system itself or the GPSr), it will simply make those previously taken accurate coord readings and make them not accurate. Affect geocaching perhaps, but not the system.

The shift WILL affect printed maps and previously programmed mapping.

 

No the earthquake won't affect the system but yes, it will affect most everything else.

[+skullsoup432]

The earth also wobbles on its axis.

 

 

 

Chandler wobbleFrom Wikipedia, the free encyclopediaJump to: navigation, search

The Chandler wobble is a small motion in the Earth's axis of rotation relative to the Earth's surface, which was discovered by American astronomer Seth Carlo Chandler in 1891. It amounts to 20 feet (9 meters) on the Earth's surface and has a period of 433 days. This wobble combines with another wobble with a period of one year so that the total polar motion varies with a period of about 7 years. The Chandler wobble is an example of the kind of motion that can occur for a spinning object that is not a sphere; this is called a free nutation. Somewhat confusingly, the direction of the Earth's spin axis relative to the stars also varies with different periods, and these motions (caused by the tidal attraction of the Moon and Sun) are also called nutations, except for the slowest, which is the precession of the equinoxes.

 

The existence of a free nutation of the Earth was predicted by Isaac Newton in Corollaries 20 to 22 of Proposition 66, Book 1 of the Philosophiæ Naturalis Principia Mathematica, and by Leonhard Euler in 1755 as part of his studies of the dynamics of rotating bodies. Based on the known flattening of the Earth he predicted that it would have a period of 305 days. Several astronomers searched for motions with this period, but none were found. Chandler's contribution was to look for motions at any possible period; once the Chandler wobble was observed, the difference between its period and the one predicted by Euler was explained (by Simon Newcomb) as being caused by the non-rigidity of the Earth. The full explanation for the period also involves the fluid nature of the Earth's core and oceans: the wobble in fact produces a very small ocean tide with an amplitude of c. 6 mm, the pole tide, which is the only tide not caused by extraterrestrial bodies. Despite the small amplitude, the gravitational effect of the pole tide is easily detected by the superconducting gravimeter (see e.g. Fig. 2.3 in Virtanen 2006).[1]

 

To measure the wobble, the International Latitude Observatories were established in 1899. (The wobble is also called the variation of latitude.) These provided data on the Chandler and annual wobble for most of the 20th century, though they were eventually superseded by other methods of measurement. Monitoring of the polar motion is now done by the International Earth Rotation Service.

 

The wobble's amplitude has varied since its discovery, reaching its largest size in 1910 and fluctuating noticeably from one decade to another. While it has to be maintained by changes in the mass distribution or angular momentum of the Earth's outer core, atmosphere, oceans, or crust (from earthquakes), for a long time the actual source was unclear, since no available motions seemed to be coherent with what was driving the wobble.

 

Richard Gross (2001) of the Jet Propulsion Laboratory, California, used computer simulations to discover the source of the Chandler Wobble. Gross found that two thirds of the 'wobble' was caused by fluctuating pressure on the sea bottom due to temperature and salinity changes and wind-driven changes in the circulation of the oceans. The remaining third is due to atmospheric fluctuations [2]

 

 

Doesn't have much to do with plate tetonics (I think that's what the shifting is called), but still kind of mind boggling, no?

[+Chrysalides]

The earth also wobbles on its axis.

This kind of sloppiness is unacceptable and is a sign of our moral decay!

 

The "8 ft shift" - some reports say the entire Japan moved, but more reliable reports seem to say "coast" and "a large part" but I can't seem to find out which part. Near the epicenter, I would guess. Since Japan sits on 3 tectonic plates, the whole country shifting that much seems unlikely.

 

Just out of curiosity I looked at the geocaching map for the area around Sendai. There's one right at the airport where the tsunami washed over. There's a collection of notes from cachers from all over the world. U.S. is already represented so I didn't add any more - not that the locals would be viewing that page any time soon. Wishing the people there all the best. Earthquake, tsunami, and now the possibility of a nuclear core meltdown. They have more than their fair share of bad fortune.

[+Peanuthead]

The earth also wobbles on its axis.

 

Just out of curiosity I looked at the geocaching map for the area around Sendai. There's one right at the airport where the tsunami washed over. There's a collection of notes from cachers from all over the world. U.S. is already represented so I didn't add any more - not that the locals would be viewing that page

 

I believe you are referring to cache GC2173Z.

 

http://tinyurl.com/68njc8w

click above

 

And it sure would be comforting to hear something from the cache hider tmiya, who is from Miyagi, and for whom I am worried, though we have never met.

Edited March 12, 2011 by Peanuthead

[+John in Valley Forge]

I read a month or so ago about how the entire North American plate moves 3 inches or so to the WSW each and every year. Thus shifting all caches in the USA that much each year. 10 year old caches have moved 30 inches since placement. Furthermore smaller fault zones move as much as 10" per year across the country in varying directions. Caches in those areas have moved a staggering 100 inches in 10 years!!!

 

AHA!

That's why I can never find anything.

[+Chrysalides]

I believe you are referring to cache GC2173Z.

 

http://tinyurl.com/68njc8w

 

And it sure would be comforting to hear something from the cache hider tmiya, who is from Miyagi, and for whom I am worried, though we have never met.

Google has released overlays for some of the areas devastated by the earthquake and tsunami. You can see the area this cache is at, before and after. The green is now covered by brown, presumably mud. To the east you can see the parking lot, apron and part of the runway covered with mud and debris.

 

To see the overlay download the KML from google. I got it from the twitter feed of @earthoutreach

 

KML : http://bit.ly/dWb6bz

 

At around N 38 10.400 E 140 57.000, you can see where a thick cluster of what appears to be residential houses are all wiped out. I hope they managed to get away in time.

Edited March 13, 2011 by Chrysalides

[+Don_J]

I believe you are referring to cache GC2173Z.

 

http://tinyurl.com/68njc8w

 

And it sure would be comforting to hear something from the cache hider tmiya, who is from Miyagi, and for whom I am worried, though we have never met.

Google has released overlays for some of the areas devastated by the earthquake and tsunami. You can see the area this cache is at, before and after. The green is now covered by brown, presumably mud. To the east you can see the parking lot, apron and part of the runway covered with mud and debris.

 

To see the overlay download the KML from google. I got it from the twitter feed of @earthoutreach

 

KML : http://bit.ly/dWb6bz

 

At around N 38 10.400 E 140 57.000, you can see where a thick cluster of what appears to be residential houses are all wiped out. I hope they managed to get away in time.

 

My God! A whole city has basically disappeared. I just saw a report on CNN where some of the people that fled to higher ground said that their neighbors stayed behind, in their houses.

 

Thanks for the link.

[+Chrysalides]

My God! A whole city has basically disappeared. I just saw a report on CNN where some of the people that fled to higher ground said that their neighbors stayed behind, in their houses.

I saw on BBC where they reported about the town of Minamisanriku. It was a town of approximately 19,000. Half of the population are currently missing. The BBC has some before / after photos. Pretty much the only thing left standing in the town is the hospital.

 

I'm guessing (and fervently hoping) that the large number of people unaccounted for sought refuge elsewhere, and just haven't been able to communicate their whereabouts. Every time I think there's nothing left to shock me about this disaster, something new comes up.

[+Student Camper]

The earth also wobbles on its axis.

 

 

 

Chandler wobbleFrom Wikipedia, the free encyclopediaJump to: navigation, search

The Chandler wobble is a small motion in the Earth's axis of rotation relative to the Earth's surface, which was discovered by American astronomer Seth Carlo Chandler in 1891. It amounts to 20 feet (9 meters) on the Earth's surface and has a period of 433 days. This wobble combines with another wobble with a period of one year so that the total polar motion varies with a period of about 7 years. The Chandler wobble is an example of the kind of motion that can occur for a spinning object that is not a sphere; this is called a free nutation. Somewhat confusingly, the direction of the Earth's spin axis relative to the stars also varies with different periods, and these motions (caused by the tidal attraction of the Moon and Sun) are also called nutations, except for the slowest, which is the precession of the equinoxes.

 

The existence of a free nutation of the Earth was predicted by Isaac Newton in Corollaries 20 to 22 of Proposition 66, Book 1 of the Philosophiæ Naturalis Principia Mathematica, and by Leonhard Euler in 1755 as part of his studies of the dynamics of rotating bodies. Based on the known flattening of the Earth he predicted that it would have a period of 305 days. Several astronomers searched for motions with this period, but none were found. Chandler's contribution was to look for motions at any possible period; once the Chandler wobble was observed, the difference between its period and the one predicted by Euler was explained (by Simon Newcomb) as being caused by the non-rigidity of the Earth. The full explanation for the period also involves the fluid nature of the Earth's core and oceans: the wobble in fact produces a very small ocean tide with an amplitude of c. 6 mm, the pole tide, which is the only tide not caused by extraterrestrial bodies. Despite the small amplitude, the gravitational effect of the pole tide is easily detected by the superconducting gravimeter (see e.g. Fig. 2.3 in Virtanen 2006).[1]

 

To measure the wobble, the International Latitude Observatories were established in 1899. (The wobble is also called the variation of latitude.) These provided data on the Chandler and annual wobble for most of the 20th century, though they were eventually superseded by other methods of measurement. Monitoring of the polar motion is now done by the International Earth Rotation Service.

 

The wobble's amplitude has varied since its discovery, reaching its largest size in 1910 and fluctuating noticeably from one decade to another. While it has to be maintained by changes in the mass distribution or angular momentum of the Earth's outer core, atmosphere, oceans, or crust (from earthquakes), for a long time the actual source was unclear, since no available motions seemed to be coherent with what was driving the wobble.

 

Richard Gross (2001) of the Jet Propulsion Laboratory, California, used computer simulations to discover the source of the Chandler Wobble. Gross found that two thirds of the 'wobble' was caused by fluctuating pressure on the sea bottom due to temperature and salinity changes and wind-driven changes in the circulation of the oceans. The remaining third is due to atmospheric fluctuations [2]

 

 

Doesn't have much to do with plate tetonics (I think that's what the shifting is called), but still kind of mind boggling, no?

I agree with what he said, What did he say? My head is starting to hurt.

[+hzoi]

Icelandic caches are constantly on the move. There's a rift zone about 15 miles or so east of Reykjavik, where the North American and European plates are pulling away from each other. As a result, the island gets slightly wider all the time. Google tells me it's about 4 cm per year, though, so we've got some time before we're outside the accpetable radius for geocaching.

[+northernpenguin]

 

I believe you are referring to cache GC2173Z.

 

http://tinyurl.com/68njc8w

click above

 

And it sure would be comforting to hear something from the cache hider tmiya, who is from Miyagi, and for whom I am worried, though we have never met.

 

I agree. It's worrying to see the last login Thursday, March 10 on tmiya's cache profile page. Particularly when looking at Google Maps for where Miyagi is (Sendai). Hope they are OK.

[+BigFurryMonster]

See http://www.nytimes.com/2011/03/14/world/asia/14seismic.html

 

According to this:

 

• Parts of Japan moved 13 feet (about 4 meters) to the east. Japan is now wider than before. This offsets Japan's westward movement somewhat.
  
• Parts of Japan's coastline are low 2 feet (about 60 cm) lower than before.
  
• The Earth's day has shortened by a few millionths of a second.
  
• The Earth's 'figure axis' (the axis that the Earth's mass is balanced around) is shifted by 6.5 inches (less than 3 cm).
  

[+Chrysalides]

The Earth's day has shortened by a few millionths of a second.

I did some simple calculations that hopefully is not too far wrong. Each microsecond change in the day length affects position by less than 0.5mm per day, assuming no correction. And I believe the satellites are sent correction information frequently.

[+thecaswellfamily]

The Earth's day has shortened by a few millionths of a second.

I did some simple calculations that hopefully is not too far wrong. Each microsecond change in the day length affects position by less than 0.5mm per day, assuming no correction. And I believe the satellites are sent correction information frequently.

 

Oh wow, I knew SOMEBODY on here would know how to calculate all that! Thank you for that... in the meantime our prayers continue to be with all those over in Japan...

[knowschad]

The Earth's day has shortened by a few millionths of a second.

I did some simple calculations that hopefully is not too far wrong. Each microsecond change in the day length affects position by less than 0.5mm per day, assuming no correction. And I believe the satellites are sent correction information frequently.

 

Oh wow, I knew SOMEBODY on here would know how to calculate all that! Thank you for that... in the meantime our prayers continue to be with all those over in Japan...

 

I think the geocaching accuracy in Japan right now is about a -9.0 on the Richter scale of importance right now. I agree with your prayer thought, though.

[+Chrysalides]

I think the geocaching accuracy in Japan right now is about a -9.0 on the Richter scale of importance right now. I agree with your prayer thought, though.

Your analogy has a flaw. That would make it extremely important.

 

Anyway, I don't think anyone seriously think that geocaching is on anyone's mind in Sendai, though I still see a few caches getting logged in Tokyo when I checked prior to posting this.

 

The question of how a massive earthquake affects GPS accuracy is a popular one though, and it almost always crops up after a major tremor. I doubt the effect is measurable even for surveyor grade GPS receivers, except for the immediate area where the Earth's crust shifted, but I do not know for sure.

[+Sky King 36]

For the first time, we'll have caches archived, and unrecoverable, for reasons of radioactive contamination. I really want to make a funny one-liner about a new "radioactive" attribute, but the situation just gets so much graver, and so much worse than we were being led to believe, that even gallows humor is a tough sell for me today.

 

I was caching a lot in Eastern Iowa both during the historic Cedar River flood of 2008 and the very damaging smaller floods of 2009 and 2010... A lot of caches were lost, rising water does a number on them. I can't imagine how many cahces were lost in the tsunami this time, or in Indonesia a few years ago.

[+Happy Bubbles]

For the first time, we'll have caches archived, and unrecoverable, for reasons of radioactive contamination. I really want to make a funny one-liner about a new "radioactive" attribute, but the situation just gets so much graver, and so much worse than we were being led to believe, that even gallows humor is a tough sell for me today.

 

I was caching a lot in Eastern Iowa both during the historic Cedar River flood of 2008 and the very damaging smaller floods of 2009 and 2010... A lot of caches were lost, rising water does a number on them. I can't imagine how many cahces were lost in the tsunami this time, or in Indonesia a few years ago.

 

No, we won't. Fukushima Daiichi is located at N 37 25.378 E 141 01.975. The nearest cache is an earthcache 20 miles away, which is outside the current evacuation zone. It's extremelyunlikely that there will be any lasting radioactive contamination in an area wide enough to include any caches.

[+HomeStyle]

I'm not sure many people will willingly go within 20 miles of that meltdown after hearing today's news on the nuclear reactors. I am also curious about whether or not the gpsr's would still be functional during search and rescue efforts. In such devastation, it would seem impossible to follow the usual "take a left on main street and go three blocks" kind of directions. Gpsr's might be their sole way of navigating for now, maybe?