TIGHAR
Amelia Earhart Search Forum => The Islands: Expeditions, Facts, Castaway, Finds and Environs => Topic started by: Jeff Victor Hayden on May 01, 2012, 01:13:49 PM
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As the reef at Niku seems to play an important part in the Tighar hypothesis I thought it might be interesting to discuss the reef environment and dynamics, especially as we are going to be seeing and hearing a lot more of it in the coming months.
Here's a link to a paper on reef dynamics and sedimentation, copyrighted so you will have to read his work via the link.
http://www.kmec.uhh.hawaii.edu/QUESTInfo/reefsEDM.pdf
(http://www.kmec.uhh.hawaii.edu/QUESTInfo/reefsEDM.pdf)
Here's a couple of images of a typical reef layout, if you can find any better ones that match the Niku reef that would be helpful.
(http://)
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Wonder how much the reef has changes due to seismic activity, and the big waves over the years. That would be interesting to know.
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This is the Gardner Island seamount (they have it as Niku' on top of the seamount name of Gardner) as it fits in with the surrounding seamounts in the area. It clearly shows the main feature of seamounts, the steepness of the drop-off towards the Abyssal plain.
(http://)
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Yikes!! Thanks Jeff. Those are very dramatic graphics. It just goes to show that this summers expedition needs a vessel and equipment as serious as KoK.
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This is the Gardner Island seamount (they have it as Niku' on top of the seamount name of Gardner) as it fits in with the surrounding seamounts in the area. It clearly shows the main feature of seamounts, the steepness of the drop-off towards the Abyssal plain.
(http://)
But notice that the vertical scale of the first graphic is greatly exaggerated. Look at the second graphic. Starting at the intersection of 4° 40' S, 174° 30' W (approximately the presumed location of the landing) and going straight west you have to travel 3.06 NM to descend 1,000 meters, the first heavy line. (Each square is ten nautical miles, 18,520 meters.) (For some reason the contour lines above 1,000 meters are not spaced at 100 meters as the legend states. Or, if they are, then the color coding is wrong.) 3.05 NM is 5,660 meters. 1,000 meters of descent over a horizontal distance of 5,660 makes the slope only 10.2°, not nearly as steep as it appears at first blush. (If the contour lines are actually 100 meters then the first heavy line is only 500 meters so the angle would only be 5 degrees instead of 10.) Does anybody know the angle of repose of pieces of aluminum on a bed of coral? I suspect that it is a lot steeper than ten degrees.
gl
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Yes Gary, I think the first image is for illustrative purposes only, not to be taken as gospel. Here's a link to the seamount catalog that might help...
http://earthref.org/cgi-bin/sc-s2-list.cgi?database_name=sc&search_start=main&selected_smnt_id=65 (http://earthref.org/cgi-bin/sc-s2-list.cgi?database_name=sc&search_start=main&selected_smnt_id=65)
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Spur and groove video from Youtube. Must be shallow water due to the presence of the scuba divers but, gives us some idea as to the landscape. Any video or images of spur and grooves or even a reef at 300 meters would be captured using an ROV, haven't found any, yet.
http://youtu.be/Na4dMzVp-aY (http://youtu.be/Na4dMzVp-aY)
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That video is fairly representative of the reef at Niku just offshore of the break in the reef flat, shallow water down to about 30 ft. Below that the grooves are basically lost in the sauce, so to speak. None of the 2010 ROV video was taken in this area as I understand it, they started farther off shore in deeper water, but in 2001 we did dive most if not all of the spur and grooves between the landing channel all the way up to near the NW tip of the island. We literally swam up each groove from slightly offshore where the grooves were some 20 ft deep right on up to the surf line where the reef flat starts. Made for some interesting diving with the surge that was also trying to move up and back through the grooves.
Andrew
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Very good points, well presented.
I would add that as the surfaces of the wings and tailplane etc... were designed to provide lift and control during flight through air then, they would still perform this function when water, moving fast enough, passed over them. A bit like a sail on a yacht catching the wind maybe. Currents, tides, storms...?
Just a thought.
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Gary
This link has quite a lot of research data from the Phoenix islands including Nikumaroro. The slope on the reef is given as being between 45 and 85 degrees depending on how far you are from the surf line and the location.
http://www.phoenixislands.org/pdf/00589.02.pdf (http://www.phoenixislands.org/pdf/00589.02.pdf)
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Gary
This link has quite a lot of research data from the Phoenix islands including Nikumaroro. The slope on the reef is given as being between 45 and 85 degrees depending on how far you are from the surf line and the location.
http://www.phoenixislands.org/pdf/00589.02.pdf (http://www.phoenixislands.org/pdf/00589.02.pdf)
That report is interesting but its purpose was to catalog the reef area for ecological research purposes. It does make the general statement that the slopes vary from 45° to 85° but that is not specific to Gardner. In fact it points out that offshore of Gardner "on the western shore where the reef drops from the intertidal rim to > 40 m within 50 m in some locations." The clear reading of this is that most of the reef is not that steep but only in some locations is it that steep. Taking "> 40 meters " as meaning approximately 50 meters, within 50 meters makes the slope, in some locations only, approximately 45°. This is apparently so unusual that it required this specific comment.
Looking at the bathymetric map again and this time looking to the east along the 4° 40' S parallel and looking at the spacing between 1,000 and 2,000 meters of depth covers 1.9 NM, 3,600 meters making the deep slope in that area only 17° so the 45° to 85° slope statement does not appear to be applicable to the reef around Gardner.
So unless there is some reason to distrust the bathymetric chart I think it trumps the general statements in the report you referenced.
(https://tighar.org/smf/index.php?action=dlattach;topic=672.0;attach=2338)
gl
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Yes, there hasn't been a lot of oceanography research in this part of the Pacific Gary.
'Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap.'
As you mentioned, the drop off varies quite considerably around the Gardner Island seamount. Will be interesting to see the actual slope where the aircraft wreckage is theorised to be this coming July.
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Here are some items that should help us understand the reef and how fast it drops off.
Courtesy of James Thompson of GIS Services is a series of graphics of the soundings made by the Bushnell Survey of 1939. Jim took the soundings made by the Bushnell and input them into his GIS software to create these interesting items such as the .kmz files that can be opened in Google Earth. You can select a single sounding in GE and it will tell you the coordinates and the depth.
For the file called TIN2.pdf (the colorful one), make sure you zoom way in and you will see the locations and actual Bushnell soundings recorded. The color stuff is actually overlaid on top of the actual Bushnell survey which you can see around the far edges. I think it is a beautiful piece of work by Jim Thompson.
Gary, having been diving on the reef, most of it gets pretty steep, pretty quickly, not just in "some places" - the nearest soundings to shore start at 30+ fathoms and drop off quickly to 300+ fathoms, so I don't think 17 degrees is accurate. No doubt you will calculate the angle from the info in the Bushnell survey, and I look forward to your analysis.
Andrew
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Andrew, thanks for the information. Your task ahead does seem to be more daunting than I realised. I wish you all the best of luck.
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Thanks for the vote of confidence, but I'm not going on the upcoming trip. Wish I were, but it will mostly be a pretty small crew of specialized folks.
By the way, it is not my task, or even Ric's task, it is OUR task. Like it or not, you are all involved now, sucked into the vortex, part of the process and the project. :)
Andrew
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here's a link to some fish round Gardner :)
http://www.nationalgeographicstock.com/ngsimages/lightbox/share/publishedlightboxcomp.jsf
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Hi Ric,
If the plane landed as I believe on the reef shelf. It would seem it would have been taxied as close to the beach as possible during the low tide period on arrival. This would have decreased the high tide exposure and further prevented movement of the 7500+- pound object to tidal actions as no current exist on the reef shelf. After coming to a stop the tail assembly quite proably took on some water leaving the cockpit and wings high and dry to the 54 inch high tide effect especially if it was closer to a shore position. Additionally any movement by wave force would have further moved the plane toward shore not out to sea. This exposure from 1 July to the morning of 9 July, 1937 when the Navy overflight occured begs to suggest the plane was in fact proably moved or the 55 foot wing span shinny metel aircraft would have been spotted much as shown in your presentation "Where is the Electra"!
I hope on your next survey a shore party will have use of metal detectors in searching the highest point or points for a rubberized bag which was carried on the plane, that may contain film canisters, an octant and a sextant. The odds are much less for locating the plane.
Best Wishes!
FN
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Interesting points Harold which made me go back through the tighar files to find this image. I was wondering, just for arguments sake the dark shadow in the image was the Electra, check the scale of it compared to the super-imposed one in the image, it doesn't stand out as much as I thought it would. looks quite small in fact. I believe the search planes were a lot lower though. Correct me if I'm wrong on that.
(http://)
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Harold's post and the image Jeff posted got me thinking. If the Electra did land on the reef flat, at some point AE and FN would likely have tried to get off the reef onto the island proper. Everything I've read on this site tells me to that picking your way across the reef at anything except dead low tide is extremely difficult if not downright dangerous. Given that fact, what is/would be the "path of least resistance" our castaways might follow to get to the beach, skirting the holes and deep valleys that are more prevelant inshore of the reef. Wherever this path hits the beach might be a good starting point for Harold's idea of a search for "camp zero" (assuming wind and wave from 75 years of storms haven't altered the shoreline or piled-up debris too high to make any search very much more unlikely to turn up anything significant.
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I hope on your next survey a shore party will have use of metal detectors in searching the highest point or points for a rubberized bag which was carried on the plane, that may contain film canisters, an octant and a sextant.
I don't think we have a comprehensive map of every part of Niku that TIGHAR has surveyed with metal detectors, but I'm pretty sure they have covered the ground closest to the suggested landing site more than once.
So, of course, did the colonists on the island, albeit without benefit of using metal detectors.
I'm moderately confident that there is not a rubberized bag sitting on or near the surface, full of any-idiot artifacts; if it ever was there, some idiot has walked off with it. That said, there has been discussion of having another go at Nutiran (http://tighar.org/wiki/Nutiran), searching for "camp zero." That won't happen during the 2012 expedition, which will be fully preoccupied with the deep-water work.
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I was at a loose end this morning so, with nothing better to do I went through the ROV footage again. The object was to find anything that looks as though it is alive, coral, fish, polyps, sponges, crustaceans, molluscs etc...
Apart from some brown stuff wrapped around the wire/rope there is nothing at all that shows any signs of life, no fish, nothing. Just piles of coral rubble and white sediment. Even at depths of 1000 metres there is usually living creatures, living coral, seaweed, plant life etc... Here, there is nothing.
Any one have any ideas as to why the reef at this particular location is so desolate, there is absolutely nothing. Is it something to do with seamounts or, just this one?
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I was at a loose end this morning so, with nothing better to do I went through the ROV footage again. The object was to find anything that looks as though it is alive, coral, fish, polyps, sponges, crustaceans, molluscs etc. ...
Any one have any ideas as to why the reef at this particular location is so desolate, there is absolutely nothing. Is it something to do with seamounts or, just this one?
Niku has suffered some "reef bleaching" (http://www.neaq.org/conservation_and_research/climate_change/climate_change_and_the_oceans.php#coral) since 2002. It may be that the ROV footage was focused on one of the damaged areas.
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Jeff,
beg to differ and can't find the post but I posted a spot of a i valve shell (ok could be a dead un) in the footage and suggested it as something to help ID size.
Didn't add a time stamp but there was one in shot.
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The reef did suffer during the warming of 2002, and was considerably less robust in 2007 than what we saw in 2001, but in our opinion had largely recovered by 2010. I don't think this is the reason for the lack of wildlife in the video.
I think the lack of things to see is a function of four things, one the ROV is being operated by a human who is selectively looking close in at the reef face in hopes of seeing man made things instead of wildlife, and second that the ROV itself, being a strange object, tended to cause the wildlife to move away, and third, the depths where the ROV was operating there is less wildlife to be seen, and fourth is the footage that has been made available seems to focus on the reef face not wildlife.
I know that we did see some interesting critters in the video that was shot by the ROV, one that we had a very hard time identifying that had the head of a shark and the body of an eel (we thought it might even be a new species), so there definitely is some footage of wildlife out there, but I don't know that it is available. I don't know how many hours of ROV footage there is but it is likely over 100 hours, so it is a huge amount of video.
Andrew