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Caldera - Goodbye New York 2
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| [Note Guidelines] Photographer's Note |
This is not what I had planned to post - please read below.
This is the second and final posting for the Goodbye New York sequence. Unfortunately I discovered that I had lost the photographs I was going to use with the exception of this one (I had transferred the images onto a hard drive which I then knocked over and it broke – I wasn’t that bothered as I always back-up – well not always it seems)! Anyway, this shot is from La Palma in the Canary Islands and shows the view from a feature called La Caldera de Taburiente. A caldera is formed when a volcano ‘blows its top off’. Good examples are Ngorongoro in Tanzania amd Aso in Japan. They are caused when the pressure inside the volcano is too great and the whole structure fails. A good example of this happening ON A SMALL SCALE was the Mt St Helen’s eruption of 1980 - and even then it only blew away part of the side.
One of the main substances which is erupted by volcanoes is water – in the form of water vapour, This starts to exit the volcano long before the eruption. If the vent is obstructed by very hard lava (the plug) the gas moved into the surrounding rock. Basalt is very porous – it looks a bit like a hard sponge. The pressure of the gas builds up even though some of it seeps out of the rock. The problem occurs where there are hard non-porous dykes (look back to yesterday’s posting to see this – the gas builds up like a pressure cooker and like an over-heated pressure cooker, the pressure eventually becomes too much and the whole structure fails/collapses. This is bad when it happens on land – however, when it happens at sea it displaces millions of cubic meters of water and forms a Mega-Tsunami – one happening in the Canary Islands – or even more likely the Azores – the resulting wave would/could decimate the Eastern Seaboard of the USA – from Miami to New York.
Definition
Mega-tsunamis" may be caused by landslide and rockfall phenomena, explosive volcanic events, or meteor impacts. Underwater earthquakes do not normally generate such large tsunamis; typically tsunamis caused by earthquakes (such as the 2004 Indian Ocean earthquake) have an amplitude (height) equal to the height of the displaced floor of the ocean and this is typically 10m or less (depending on how much water was displaced by the earthquake and on various natural factors such as tree cover and the general shore characteristics) but can affect thousands of kilometres of coastline and reach many kilometres inland.
The geological record indicates that "mega-tsunamis" may be generated by the failure of part of the flank of a volcanic ocean island. Structural failure of a volcanic ocean island is considered to be the most theoretically common cause of the generation of a "mega-tsunami." . Their size and power means that they can produce devastating effects; travelling across oceans and inundating upto 25 km inland from the coast. The most recent such event so far known occurred approximately 4,000 years ago on Réunion island, to the east of Madagascar. The most recent collapse occurred on Ritter Island in 1888 but it only generated 12-15 metre waves, which, although they killed 3,000 people on surrounding islands, did not cause widespread devastation.
The most recent "mega-tsunamis", such as the one at Lituya Bay in 1958 and in the Vajont Dam in 1963, have occurred as a result of landslides in largely enclosed bodies of waters and their effects were as a consequence rather limited.
Other recent "mega-tsunamis" include the 40 metre high waves generated by the collapse of Krakatoa during its eruption in 1883 which killed 36,000 people on Java, Sumatra and the small islands around them; and the collapse of much of Santorini during its cataclysmic eruption approximately 3,615 BP (1615 BC). It is estimated that it produced a wave that surged to 100-150 metres and devastated much of the north coast of Crete after travelling 70 kilometres. However, these "mega-tsunamis" did not travel thousands of miles to cause more widespread damage, in part leading to the controversy about whether the waves produced by island collapses travel great distances in the same way that tsunamis do.
Some recent work by scholars (Egyptologists and Israeli plus others), geologists and oceanographers (including Dr Iain Stewart of University of Plymouth, UK), indicates that the Santorini eruption (about 1615 BC) may have caused the devastation of the Egyptian armies that is mentioned in the Exodus. The Exodus is dated as occurring between 1290 and 1340 BC. It is unlikely that the details were recorded in the immediate aftermath and there was probably a delay in the writing of the account. Whilst there is a discrepancy of about 300 years, given the circumstances surrounding the dating of the Santorini eruption it is possible that the two events did coincide..
Volcanic ocean islands (such as the Canary Islands, Cape Verde, La Réunion and the Hawaiian Islands) may fail and generate "mega-tsunamis." The "mega-tsunami" may inundate other islands in the archipelago. Volcanic ocean islands are unstable due to the manner that they develop. They develop over-steepened flanks which have poor horizontal support. They are constructed of poorly consolidated materials piled up by successive eruptions from central vents and rifts, bisected by faults and stress lines created by ongoing volcanic activity.
Evidence for large landslides has been found in the form of extensive underwater debris aprons around them composed of the material which has slipped into the ocean. In recent years five such debris aprons have been found in the Hawaiian Islands alone. The Canary Islands have at least 14 such debris aprons associated with the archipelago. Some geologists (Day et al., 1999, Ward and Day, 2001), consider that the next "mega-tsunami" may be generated during a future eruption involving the volcanic ocean island of La Palma, in the Canary Islands. In 1949 the Cumbre Vieja erupted at the Hoyo Negro and Duraznero vents. During this eruption about 2.5 km (about 10% of the total length of the Cumbre Vieja) of the western half of the Cumbre Vieja - which is the volcanically active arm of a triple armed rift, slipped about 2 metres downwards and 1 metre westwards towards the Atlantic Ocean. It is believed that this process was driven by the pressure caused by the rising magma heating ground waters trapped within the structure of the island so that they became super-heated. This then caused part of the island's structure to be pushed apart. The volcano is still active, though dormant at present, but it will erupt again at some future unascertainable date. An earthquake was associated with this eruption and had an epicentre near the village of Jedy.
La Palma is currently the most volcanically active island in the Canary Islands Archipelago. It is postulated that a future eruption may cause catastrophic failure of the western flank of the Cumbre Vieja, though it is likely that several eruptions would be required before failure would occur. Were this to happen it is hypothesised that a "mega-tsunami" would be generated as the western half of the island, with a mass estimated at approximately 500 trillion tonnes, catastrophically slid into the ocean in a massive gravitational landslide, causing a wave with a initial amplitude (height) estimated to be about 1000 metres and a likely height of around 25 m at the Caribbean and the Eastern North American seaboard coast when it comes ashore about 5 or more hours later. However, this is hypothetical and is strongly debated.
It should be borne in mind that the Cumbre Vieja is approximately 25 km long, the last eruption occurred in 1971 at the southern end of the sub-aerial section without any movement. In addition the 1949 eruption occurred over approximately 2.5 km - or about 10% of the total exposed section of the Cumbre Vieja. The length is verifiable by walking the Ruta de Volcanes and is the only section that currently shows any sign of movement. Observations of the section indicate that the section is currently stationary and would not appear to have moved since the initial rupture in 1949 as the dimensions accord with those recorded at the time.
HOWEVER, there is a volcano in the Azores which is thought to be much closer to collapse...... |
nglen, Luis52, matatur, jhm, Necipp, lovenature, oanaotilia, jaycee, boreocypriensis, eqshannon, NinaM, JPlumb, rousettus, jcoowanitwong, joey, Argus, iris, albert, Heaven has marked this note useful
Only registered TrekNature members may rate photo notes. |
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- nglen
![Gold Star Critiquer/Silver Workshop Editor/Gold Note Writer [C: 2907 W: 34 N: 8619]](http://i1.treknature.com/misc/g-s-g.gif)
(32124) - [2008-03-12 10:04]
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HI HAVING TO STAY AT WORK LATE SO JUST A NOTE TO SAY GOOD PICTURE AND I WILL BE BACK .
tfs.
NICK..
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- Arjun
![Gold Star Critiquer/Gold Note Writer [C: 358 W: 7 N: 1109]](http://i1.treknature.com/misc/g-n-g.gif)
(5398) - [2008-03-12 10:08]
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Beautiful landscape.
You got the lighting very well and the greenery is lovely.
TFS
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- Luis52
(12761)
- [2008-03-12 10:18]
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Hi My Friend.
Nice Landscapes from Canarias. It looks wonderful with the sun light, very natural colors and excellent framed.
I am sad You lost Your great photos.
Long but interesting note. It took me a while to read ir.
Luis52.
Interesting topography again James, not the usual caldera we are more familiar with but the rock formations are beautiful in a sense. Your related notes, as usual, very comprehensive, Thanks my friend.
Mehmet
Ok... something else to add to my list of possible catastrophes! Actually I saw a TV special on this scenario but had thankfully put it out of my mind. It actually makes life on earth and all of man's accomplishments feel a little more amazing considering how many events have to happen in his favor.
we've been pretty lucky! I guess I won't go to New York. I'll just sit here surrounded by my own volcanoes. : )
TFS
Evelynn : )
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- jhm
(628)
- [2008-03-12 10:38]
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Hello James,
You play wonderful with light and shades, this gives a wonderful picture.
Very nice composition with the different diagonal lines of the mountains.
Great photograph work here!
Best regards,
John.
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- Necipp
![Gold Star Critiquer [C: 1110 W: 15 N: 21]](http://i1.treknature.com/misc/g-n-n.gif)
(100) - [2008-03-12 11:05]
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Hello James, good creative composition I like the gradating layered levels of light, from a fairly simple scenery youve produced a good quality picture. Lots of detail even in the dark shadowy area, good sharpness throughout. tfs Rgds Necip
Hi James.
Splendid landscape camture my friend. The topography of here is very stunning. Your capture is first no as usual. TFS.
Cheers,
Bayram
A SUPERIOR lesson...and in the image part of the study, the Canon does so well with subtle changes in contrasts and lighting. I can at times mimic this with my Nikon...but it is quite a chore. Very well then..i have learned much today and a whole bunch of it from tis one post!
Bob
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- Karin
(2089)
- [2008-03-12 15:09]
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Hi James,
Good composition of this difficult to make photo with strong light. I live on Gran Canaria and have heard about this possible colapsing of the caldera. Right in front of my house I have a view on a 1200m hight active cliff and a small dangerous road that clings on it.
Nice color degradations and fabulous wild landscape.
TFS
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- NinaM
(6594)
- [2008-03-12 15:36]
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This is a fantastic picture, with acerated cliffs and harsh nature yet beautiful! You captured it with much life and light and the notes really match the picture. My mind is racing fast when I read your notes, especially that one which refers to such grand scale phenomenon, strong and powerful. I like the richness contained in both your picture and notes. Thank you!
Francine
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- JPlumb
![Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 637 W: 166 N: 889]](http://i1.treknature.com/misc/g-g-g.gif)
(2884) - [2008-03-12 16:20]
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Hi James, speaking on the shot first; it's too bad about the loss of your other pictures, probably 90% of us have vulnerabilities in this area, where we think we're covered, but maybe not as well as we think. This is a good shot though. I like the levels you have here with different amounts of light resulting in different tones and textures. The shot is sharp with good definition throughout.
Now on to your note, which is excellent as always. With respect to the goodbye New York analogy, it is probably a very small but still distinct risk. I mentioned in my shot yesterday of the swans, about a "Black Swan Event". I didn't go into a lot of detail on it, but a situation such as this one, would represent just such an event: one that is highly unlikely, and mostly unforeseeable, yet possible, with history changing consequences. With your background, you can probably identify a couple of others that have occured similar to this.
Very good set of posts. Enjoyed!
Thanks, John
Hello James,
This is a lovely image of light and shadows displayed in the most natural way!
good pov with clarity, original colouration and details in the shot
well done and much appreciated to the notes to know!
best regards
Tony
Hello James,
Beautiful mountain scape picture. Nice seeing caldera wall from this pov. Thanks for your interesting note about volcanic eruption and tsunami. Very well done.
JC
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- PaulH
(13083)
- [2008-03-13 2:33]
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Hi James,
an intimidating and fascinating landscape that speak volumes about the Earth! Wonderful perspective created by the layers of ridges. I've heard of the threat from La Palma...i think we might be effected in the south of the UK, even in our relatively sheltered position!
Paul
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- joey
(24727)
- [2008-03-13 2:49]
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Yikes! Some shocking info you have there James!
I'm sorry to hear some of your photos have been lost :-(
Very nice shot!
The diagonal composition is brilliant!
Nice lighting.
Great detail.
Well done,
Joe
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- Argus
(34927)
- [2008-03-13 3:35]
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Hello James,
Nicely composed image of the side of a caldera. I like the perspective and depth provided by the mist in the distance.
Your note is very interesting, informative and very readable and I thank you both for that and the fine image,
Ivan
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- iris
(3016)
- [2008-03-13 3:46]
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Hello James,
There a lesson one learned and narrated to others is a lesson for others too.Many of us get caught in that situation similar to the one you faced of losing the shots!
Well but seems like your loss has been made up well by this terrific cpature of the mountains of teh Canary Islands falling away from the dark to the light from the near to the far and wide...You have used light in a very interesting way to present the highlight and shadows.
Good composition and informative notes. Being there to see a cladera and the related formations must be quite an experience.
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- Mana
(18516)
- [2008-03-13 4:39]
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Hi James,
Wonderful shot and a charming scene captured. The mountains looks awesome. Great light and shadow effect and the morning mist makes the image majestic. Very educative note too. excellent POV and composition. Kudos.
TFS.
Sumon
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- albert
(2055)
- [2008-03-13 7:26]
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I James
Nice landscape and very interesting note
Thank you
TFS
Albert
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- jaycee
(21912)
- [2008-03-13 8:22]
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Hi James,
Another educational experience! The colors and shadings are wonderful. A very beautiful scene composed perfectly. Sounds like I should be glad I moved out west after a lifetime on the east coast.
Jane
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- arfer
(0)
- [2008-03-13 9:37]
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Hello James
Wow what a view.
Your POV is incredible.
The notes are thorough and educational.
A superb TN posting.
TFS
Rob
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- Heaven
(6042)
- [2008-03-13 22:27]
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Hi James!
Thank you for the very instructive notes. And of course thank you for the beautiful picture!
I appreciat the gradation of the light density very much: from vivid colors in the foreground to bright and "washed out" ones in the background, provoked and highlighted by sharp ridges.
Kind regards
Markus
