Summary on the Mag. 8 Santa Cruz Islands quake

A 8.0 magnitude earthquake hit the town of Lata, on Santa Cruz in Temotu, the eastern-most province in the Solomons last thursday. There have been many many aftershocks, the largest of which had magnitude 7.0 and quite many earthquakes stronger than magnitude 6. The 8.0 quake caused a Tsunami which caused the death of 13 persons ( other sources speak of 9 or 10) and some people went missing. So i thought i d try to collect as many links and hints i could find on this event. Most of them were provided by readers. This is not a pretty or amusing post, just a summary of links and information:

Chyphria´s plot: 

Image: Wikimedia Commons

Image: Wikimedia Commons

The Stana Cruz Islands are a group of islands to be found in the South Pacific 250 km south of the Solomon Islands, and are located close to a tectonic plate boundary. Vanatu can be found south of them, but the tropical rain forest covering the islands is the same type as can be found on Vanatu. They are composed of limestone which is covered with volcanic ash and are surrounded by coral reefs.

Image: Wikimedia Commons

Image: Wikimedia Commons

The islands are considered rather young on geological terms, being only about 5 million years old. The largest island is Nendo, which is also known as Santa Cruz Island. Wikipedia Quote:” The term Santa Cruz Islands is sometimes used to encompass all of the islands of the present-day Solomon Islands province of Temotu.”

From Wiki “The Santa Cruz Islands are less than five million years old, and were pushed upward by the tectonic subduction of the northward-moving Indo-Australian Plate under the Pacific Plate.

We often look at the volcanoes in the area, especially after a strong earthquake happened. This earthquake was clearly a tectonic one and not volcano related.

Tinakula, Santa Cruz Island-Group, Solomon Islands (S. Pacific)

Tinakula, Santa Cruz Island-Group, Solomon Islands (S. Pacific)

John Seach relates Tinakula, but if some or any volcano really starts erupting, remains to be seen. Talla found an artcile about worries of a possible increased activity at Tinakula, an uninhabited island of the Solomons. ( Remember The Solomons lie farther north! )

List of the volcanoes in this area.

KarenZ also mentioned that Tinakula seems to be a little bit north of the earthquakes and that the Pacific Plate is subducting under the Indo-Australian plate.

USGS analysed the 8.0 magnitude earthquake and additional information about the tectonic plates can be found  in this article.

Earthquake Report started a list of the earthquakes in the Solomon Islands. and has an article last updated February 9th:
We are still looking for a list or map which displays small earthquakes. These would be important to crate plots shwoing what is really going on.
Interesting maps:

The plate boundary near the Solomon Islands is a combination of a subduction zone and a transform fault:


This map provides the latest earthquakes but the faultlines are clearly visible also. Worldwide Emergency and Risk Map pointed out by KarenZ.

A german site was mentioned by Renato who found it on FB. Some information is doubtful but there are earthquake lists to be found and aslo 2 videos.

This is Chris Rowan’s take on Solomon Islands earthquakes:
KarenZ  started a list of the recent earthquakes:
and plots of the Solomon Island EQs for 2013:
Depth v lat and depth v lon plots for the area from 1964:
Updated 2d plot of number of eqs by mag for Santa Cruz Islands Area:

Some reports were mentioned saying steam comes out of cracks on Santa Cruz Island. It is not clear to me, if this is just fear mongering or if something is really happening.

Beach balls. Image found on Twitter by Chyphria.

Beach balls. Image found on Twitter by Chyphria.

And i dont want to miss pasting GeoLurking´s take on the situation:

“Well, some of the loon theorists think that part of the plate is going snap off…. but these are the same guys that claim a basin wide crack is going to form on the pacific plate. The actual liklihood of that happening are about as good as me hitting the powerball lottery and getting struck by lightning at the same time… as well as winning the triple crown (on foot)
I’ve yammered at them to no end about the dynamics of tectonics and the lunacy of the claim.
In fact… that region is littered with old plate / plate fragment boundaries. Remains of ancient back-arc basins, etc. If anything is going to happen, one of those
boundaries will re-activate to accomedate the prevailing stress if the active boundaries can’t handle it.
It will be unique, someone will write a paper about it, and that will be it.
Volcano wise…. I don’t know how long decompression melting takes to occur (under the extensional areas). Some of one subducting plate has had a greater extent thrust just a bit deeper and into hotter material than it was sitting at before this all started. Hydrated material (rock) will pass into the area where it can more easily melt, so fresh magma is a possibility. how long that will take, or if it will then percolate up is anybodies guess.
I second KarenZ’s lament about the lack of data on small quakes. You can tell a lot from them. They can point to moving magma or stucture that we didn’t even know that was there. (like when we were watching the sill emplacements under El Hierro.)
Right now… it’s wait and see.
The system as a whole, is capable of generating tsunami, so anyone living there needs to be ready to high tail it if a large quake occurs.”

Maybe this article by Highly Allochtonous helps understanding the beach balls.

And the IRIS maps of seismic sations:

Recent articles:
Thanks for the contribution: Newby, Renato, Talla, KarenZ GeoLurking and Chyphria.

And as latest update: El Nathan mentioned this: Interesting to see what others make of the activity in the Solomon Islands, also using the info from this blog. In some way I find it amusing…. ( VC mentioned and quoted on page 2)



105 thoughts on “Summary on the Mag. 8 Santa Cruz Islands quake

  1. Thank you Spica for the summary!
    First seen it on earthquake-report, here is a beachball plot of the Solomon earthquakes from geophysics professor Jascha Polet on Twitter:

  2. Excerpt from the National Disaster Council of the Solomon Islands regarding the “pungent steam” reports:
    At 5am, people from Lord Howe Island (166.06E, 10.80S) note that a hole has formed near the lagoon and the area is covered in smoke. People from Nagu village in Santa Cruz report that three cracks opened up in the village after one of the 7.0 earthquakes that occurred on 8/9 February 2013. The people report hot, soapy (foamy) water is seeping out. The water is steaming and smells ‘volcanic’ according to the citizens of the village. New Zealand volcanological and seismic experts advise that it is not possible to know the meaning of these events without further information.

        • Spica,, that is mentioned in the official report posted by Chryphia (link above).
          I thought that was a “provocative” quote. They don’t say what volcano, and who heard that and where. Probably Tinakula?

        • Heres an intersting point

          The people report hot, soapy (foamy) water is seeping out. The water is steaming and smells ‘volcanic’ according to the citizens of the village. New Zealand volcanological and seismic experts advise that it is not possible to know the meaning of these events without further information. The Solomon Islands Government seismologist and geologist however, assessed the Tenakula Volcano and the reports of smoke and gasses emission. In fact, it is just liquefaction on areas close to the lagoon on Nanggu.

          “Soapy water” → Ever see what happens when seawater is boiled? It foams. I know this because one time, we had a fouled freshwater tank where a small amount of seawater had gotten into it. Some of the nastiest coffee you have ever had. (and the lid for the iced tea machine came off from the foam build up in it.)

          Not to mention water that is agitated and ejected “sand blow” fashion.

  3. Sort of awkward… but here it goes.

    My musings about “loon theories” were not directed at anyone or any specific thing at lunaticoutpost. In fact, the basin wide crack idea has been around for a while, and shows up due to the “Shape of Things to Come” reports. I’m sure many of you know of them. The basin wide fault is just one idea to support what they see in their linguistic probing of the future.

    From what little I have read, lunaticoutpost seems to be more grounded in “what is plausible” more than “what can scare the carp out of someone.” Thumbs up if that is descriptive of the general tone there. One thing that sets me off is unfounded meanderings designed specifically to propagate fear.

    Now… a bit more on the “basin encompasing fault.” First, I don’t see anything that can mechanically, generate that sort of energy release any where in the future. An asteroid could do it, but the impact energy would be large enough to litterally melt a sizable percentage of the Earth’s rust. In that case, the presence of a new fault would be pretty much at the bottom of the “concern” list. This impactor would have to be in the realm of the size of the moon. Something that large would be seen long before it becomes a pressing issue. Plus, there would be no hiding it. Amateur astronomers would be able to track and verify orbital parameters fully independent of any state agency and would be throwing the B/S flag at every turn.

    The thread over there mentions a large dollop of magma. I haven’t read the paper, but that would be more properly considered a super plume. This is one idea that I’ve seen kicked around to explain the large number of island volcanoes in the west Pacific. If the one in Africa that extends out to the Atlantic is a good example, then smaller “goops” of magma rise off of the superplume and form localized hotspot systems.

    What drives “superplumes?” Your guess is as good as mine. My guess is that layers of dead and ancient plates lying in the slab graveyard accumulate heat beneath them as it comes off of the core. Occasionally lower viscocity material escapes and makes it’s way towards the surface. Carrying heat energy with it as it oozes up through the mantle.

    • The latest earthquake was 1.4 miles down. Whatever it is, it’s coming up . Tokyo, watch out! I suspect that Van Westrenen / deMeijer georeactors cause plumes; a collection of them would cause a superplume. But due to vapor presure, I don’t think they culd go supercritical and biow out the moon as they posit, unless a asteroid knocked one of them into the center — or the explosion from a previous one caused pressure waves that set it off. In fact, I suspect thatwas what caused the Permian extinction: one going off at the African karoo, and another at the Hudson Bay: the mantle scars being the Carribean and scotia plates, and the kimberlite rings around each , as well as the Atlantic ridge, being the shatter rings.

      • Hmm, the theory put forward by van Westrenen / de Meijer has received quite a lot of citicism, as noted in the link by chryphia. It has trouble explaining some factors that come into play with the formation of the moon (which my unpublished Earth-Lunar-GFL-Popcorn theory does not according to me), so I’m having even more trouble believing that a supposed spinoff-event of this is currently building a superplume or whatever below the Solomon Islands, without anyone noticing until just now. And seeing that the latest earthquake was shallow does not really convince me straight away. If this was any indication, we should be VERY worried about the newly discovered supervolcano in northeastern North-Korea, which must be almost ready to erupt any time now!

        Plate tectonics and political-dictator psychology more than sufficiently explain the observed phenomena.

  4. Fault Plane.

    When a quake occurs, it operates along a fracture plane. In other words, that region that failed. We see focal mechanisms that illustrate the mechanics of the failure (beach balls) but one part of those reports that most miss, are some of the features of the fault, such as strike, slip and dip.

    Using the formulas from Wells-Coppersmith, the down dip rupture width for a Mag 7.0 reverse fault can be up to 18.2 km. That would easily allow water to descend to depths where the rock is above the boiling point of water. Even with a rather moderate gradient of 20°C/km, at 5 km, you have already reached the boiling point of water, the only thing that would keep it from flashing to steam would be the hydrostatic pressure. Let the hotter water percolate to a shallower level, and it will turn to steam once the hydrostatic pressure drops low enough.

    GL EDIT: Provided that it still retains the heat and that it has not mixed to a lower temperature.

    As for the “smells volcanic” reports… sulfur compounds don’t just produce SO2, they also make H2S. We went through this with El Hierro. H2S could be from decaying plant material in the strata. Sulfurous odors were reported in the New Madrid quakes in 1811… much of it likely coming from the noxious water in the sand blows.

    • It could also be that the shaking causes some rearrangement of sand particles if there is a layer of sand present, compacting the layer and putting slightly more pressure on the water in the pore spaces. If this then finds it way to the surface, it will flow out slowly, as you see with many big earthquakes, the liquefaction.

      If there are some gasses dissolved in the water, which I can imagine happening near a volcano, then those gasses will come out of solution when they migrate upwards with the water. Only 20 or 30 meter will do I think, since that will already put 2-3 bars of extra pressure on the water, greatly increasing the capacity to dissolve gasses.

      Those gasses, when breaking out, might give the ‘volcanic smell’ that is described. Could be SO2, but also H2S or mercaptans are very common in decaying processes and it only takes very little of it to notice a strong smell. With H2S we are talking in parts per billion (ppb) for a noticable smell, with mercaptans even less if my memory serves me correct. Also, it only takes a little bit of contamination with organic material (which is often present in the soil) for it to start creating a foam given the right conditions. Heck, even almost clear brine of many kinds can foam under the right conditions.

      • Thank You!

        Scent of a Woman (It was a movie, but a good tag line for this)

        Thiols are the sulfur analogue of alcohols (that is, sulfur takes the place of oxygen in the hydroxyl group of an alcohol)

        Human sweat contains (R)/(S)-3-methyl-3-sulfanylhexan-1-ol (MSH), detectable at 2 parts per billion and having a fruity, onion-like odor. Women liberate significantly more MSH than men.[15] (Methylthio)methanethiol (MeSCH2SH; MTMT) is a strong-smelling volatile thiol, also detectable at parts per billion levels

        Source: Wackipedia → “mercaptans

    • I wouldn’t guess the heated water & sulfur is volcanic in nature, but there isn’t any way to confirm that, and considering that it’s located in a subduction zone, there really is no way to tell.

      I would be interested in learning how that 45 degree crimp in the subduction area affects the volcanism / geology of the area. I have a hard time believing that bend has no effect here. The problem with this arc like many small island arcs, is that there just isn’t that much research into the past geologic history (since there is such a small population and it’s so remote).

  5. NTL wild guess: Ilha do Pico, Açores. Alkali basalt (typically found on rifting oceanic volcanic islands.) Santa Luzia eruption, 1718.
    From the color of the water I’d say this is the Atlantic Ocean.

  6. Pretty Significant Swarm @ Cerro Machin (Columbia). It’s calmed down since, but looks like some sort of intrusion.

    • A seismic swarm occurred on Sunday afternoon at the volcano Cerro Machín. There were about 210 small earthquakes between 16:36 and 18:00 local time, considered the report of the Observatory of Manizales as one of the most dangerous volcanoes and potential damage to Colombia, since its eruptions are explosive, compared with the Pinatubo.

  7. My “non professional” observations for day 11/2/2013 on SCI’s earthquakes
    A more dispersive pattern on Location.
    Depth still around 10 to 35km deep.
    Magnitude and Frequency decreasing.

  8. Local travel gonzos have an article about direct air service between Iceland and Alaska via Icelandair starting May 15. Flights will be between Reykjavik, Iceland and Anchorage, 7 hours long over the top. We have a few volcanoes visible from Anchorage (Spurr and Redoubt) and by May weather is starting to get pretty nice. Ice will be off the local lakes making trout available, though it will be a little early for salmon. Cheers –

    • Mmmm Salmon.

      And for anyone daft enough to think this is a good idea. IT IS A COMMERCIAL.

      Odds are pretty good that if you approach an actual bear in this manner, you will precede the salmon on the menu. That, or you are a pre-meal entertainment.. like a squeeky toy that shrieks when bitten. To a griz, you are a food item. (well, the Grizzly won’t actually hunt you like the Polar bear will, but if you present yourself as a food item, the bear will not pass it up.)

      • The white bears are the most dangerous to people. Black bears are most numerous and smallest, but have been known to attack and consume people. When they won’t go away, it is time to worry. Brown bears are not quite as numerous. Most attacks take place when a griz is either surprised or you get too close to either the young or a kill cache. Those attacked are typically not eaten.

        OTOH, you get the occasional green idiot (Timothy Treadwell) who takes his girlfriend with him to live among the brown bears for several weeks. He chose his final trip in 2003 poorly, plopping down his campsite near Katmai toward the end of the season where the local berry crop had failed. The healthy bears left him alone. A couple old, well on their way to dying bears who could no longer compete with the larger boars turned him and his girlfriend into bear scat. There is an audio recording of the festivities.

        Anchorage has brown and black bears. They are usually worst in spring when they take down moose calves in parts of town closest to the hillside. Cheers –

  9. OT: Humor.

    I have to set this up because I thought Ken was correct at first. In retrospect, he’s dead wrong.

    Rake: short for rakehell, is a historic term applied to a man who is habituated to immoral conduct, frequently a heartless womanizer. Often a rake was a prodigal who wasted his (usually inherited) fortune on gambling, wine, women and song, incurring lavish debts in the process.

    • My apology to anyone who finds it offensive. I strongly believe that humor is where you find it and to enjoy it when you can. With as much B/S and tripe that the world has to offer, all relief is appreciated.

      Where Ken Jennings went wrong. His answer is a colloqial expression of a profession. A trade skill. What they do generally is driven by economic circumstances and is not nessesarily for enjoyment. The riddle specifically asks for an immoral pleasure seeker, “the rake” who would most likely be one who seeks the services of the person that Ken answered. I’ve known a few in that profession, and pleasure is not what they seek. Subsistence is.

  10. Katla: there has been recently several more large and deep earthquakes around Katla. This is the sign I have been expecting since 2010 to be observed a few months before an eruption.

    These earthquakes have been occurring now for a couple of weeks. It is the first time since Eyjafjallajokull that the area experiences more than ocasional deep earthquakes, and one of them today was a 2.6 (although with a poor quality). If they sustain for a few months and become larger and more shallow, then an eruption is much more likely than before! Just as it happened with Eyjafjallajokull, for 3 months before its eruption.

    And if sudden GPS movements are recorded, that makes an eruption extremely likely (like it did with Eyjafjallajokull), but this has not happened yet, but I also expect it to occur, later (a couple of weeks before the eruption). It’s time to pay a more close attention to Katla.

    • I think closer to 45 kt based on my rough calcs. (1,876,350 Cheeseburgers equivalent food energy)

      And, just in case some retired seismologist with nuclear weapons experiance happens by here. The waveforms as seen by a seismo 370 km away. (Via IRIS Buffer of Uniform Data and SeisGram2K)

      I did the same waveform pull for the previous “tests” that NKorea did. I wasn’t entirely convinced that ‘dear leader’ had not filled a mineshaft with ANFO and set it off. This time it’s more convincing (to me).

  11. Now at a depth of 0.6 miles. Nendo is a bit bigger than the collection of 3 islands around Krakatoa, isn’t it? Then again, its shape isn’t that of a ring, so much as being that of a plume. Hopefully an eruptio there will be no worse than iceland or Hawaii.

    • Is Nendo Island even volcanic? GVP doesn’t list a volcano there, only Tinakula, which is some 30 km north of Nendo. Might have been nice to figure that out first.

      Sidenote: there are some volcanoes in that area that have awesome names, like Lolo, Bam (Boom in Dutch) and Blup Blup 😀

      • It is described as uplifted limestone and volcanic ash (wiki). Although it is near the plate boundary, the maps I have seen (basic internet searches) show that there is a transform fault and a subduction zone in the area. A volcanic past would not be surprising.

        • I think the fact that the island is composed of limestone and volcanic ash is telling.

          Currently, there is only one (known) volcano in the region (tinakula). Most assume Tinakula is at least relatively effusive with it’s eruption styles, so that leads to two possible conclusions.

          1. The volcanic ash located on the Santa Cruz Islands comes from another volcano in the region which is hidden beneath the ocean.

          2. The volcanic ash located on the Santa Cruz Islands comes from Tinakula, which has a much more potent eruptive potential than people would have otherwise thought.

    • Still going on whatever it is – wouldn’t something show up on the other sensors nearby? Maybe a machine malfunction?

    • I don’t know what this is. Could be malfunction. Looks like that.

      But stations around Hekla have been showing some micro-earthquakes recently. And also some detected earthquakes around Hekla showing in recent weeks.

      I think Hekla, like Katla, is also closer to an eruption. Its exciting to realize this. I bet Hekla will erupt within the next few months, and Katla within the next couple of years. Geologically this is “almost there”,

  12. A distinct red varying light on the Mila Hekla cam. Best seen on full screen. Sure it means nothing. If Hekla decided to go, then sure more violent than a red glow then…

  13. OT

    Gulf of Mexico Forecast:

    W 10 TO 15 KT LATE. SEAS 5 TO 7 FT. 

    5 to 7 foot seas. Peicemeal for a ship 893 feet long and 116 feet wide. But right now, I bet that there are a lot of people who would prefer to be elsewhere. According to the news, the Carnival Triumph is “stinking” in the Gulf of Mexico. I think the author of the story enjoyed coming up with that descriptor.

    News reports mentions “sewage running down the walls.” It seems that the ship had an engine room fire, and now the problem has been eliminated (extinguised I imagine), has found itself flying two black balls for a dayshape. “Vessel not under command” In other words, no propulsion or ability to maneuver.

    With up to about 3600 people on board, using normal human fluid intake as a measure, that’s somewhere around 8468 to 13623 liters of urine and whatever solids go along with that that the CHT system (confinement, holding and transfer) has to deal with. I imagine that with damaged electrical systems and no power for pumps… the tanks got full. Even if you are far enough out to “pump and dump,” with the system inoperable, your screwed when the tanks fill.

    ALLEGEDLY, the ship is being towed to Mobile Alabama, the closest port. (and they have the requisite companies there to effect repairs if they choose to) If so, this is a smart move on the part of Carnival. I’ve been at sea with not power on a ship. It ain’t fun.

    I don’t know how their fresh water systems work. But steam ships use a lot of fresh water. Flash evaporators are very effective at producing it, but when they broke or were damaged, we immediately went onto “water hours” (rationing) in order to save water for the boilers. At one time we were on water hours for so long, that when we transited the Panama Canal we set up low velocity fog applicators on the fantail and allowed us to take swimming trunk showers. The logic was that since the fire-main was being flushed with freshwater from Lake Gatun, (okay, not actually “fresh” but not salt brine) it only made sence to clean up while you could. Some didnt’ take the fact that it was still tropical lake water to heart and were brushing their teeth with it. Not a smart move. They saw the folly of that action the next mornign when teh sunlight was glinting off of the most iridescent green slime that you have ever seen. I never knew anything could be that green.

    Anyway… it probaly sucks on that cruise ship right now…. but they get to go to Mobile’s Mardis Gras and watch the rednecks throwing moon pies off the floats. :D.

    Over heard on the radio today. A Florida Surfer who was posing for a photoshoot had to get stitches after a shark bit him on the hand.

    “Come to Florida and Enjoy the Surf! ow!

  14. We had a 5.0 quake this week in mid atlantic. Is it possible one day to have a quake there that would send tsunami towards Uk. If not why not? If possible what size depth would it take to cause a problem. Uk is funnel shaped from that location. Ie bristol channel which if it happened would exasperate situation. However i hear no thoughts on thishappening one day and wondered why its not a possible scenario.

    • I think its not likely. Look at Atlantic Ridge´s in general. It is NOT one plate going under another, but expansion, and lateral expansion does not generally generate tsumanies. Floods of this magnitude have been mentioned in relation to large quakes off Spain or Portugal, but not particularily in relation to Ireland or Britain (Wales, Scotland and England). So I say: No Worries. Better prepare for days of ash fallout from Iceland volcanoes, we certainly have no cash left 🙂

    • It is possible there was a tsunami that hit the Bristol Channel in the mid 17th century. Either that or a massive storm surge – it took away chunks of the Welsh coast and inundated the Somerset Levels. There was a TV programme about it a couple of years ago. The people who believe it was a tsunami point to earthquakes off the Irish coast (if memory serves me). There was a tsunami on the south coast of England associated with the great Lisbon earthquake.

      • It was worst up the Bristol Channel where it is said it left some people clinging to the top of church towers in a well-populated area or so the details were recorded.

  15. This was in response to floodwarn, but a technical difficulty (unrelated to forum operations) wound up having me post at the end of the comments. In essence, I had a crash about halfway through the post and had to pick up from where I left off.

    It is possible… but its a pretty rare set of circumstances that could cause it.

    In order for a tsunami to form, a large quantity of water has to be rapidly displaced. Subduction zones have a plate being pushed under another, from time to time (usually always) these two plates that are pushing towards each other will stick. That does not stop the overall motion of the plates, and one can develop a sizable amount of energy stored in a flexed plate… one that slowly bends to accommodate the movement. When the sticking part gives way, it allows the flexed region to relax. This adds to the energy release. “Reverse Faults” are the usual focal mechanism, depending on size, they can lift the ocean floor a few meters in a very short period of time. This is a megathrust quake, that can make events like the Japan or Sunda Plate tsunamis.

    The atlantic does not have a lot of places where this can happen. Down by the lesser and Greater Antilles, there are subduction zones, but they are pretty small.

    Another configuration that can generate a tsunami, are areas where an undersea mountain is rapidly shoved to one side. In this case, the water is displaced in a similar method to a using a wedge in golf. This would be possible along transforms (normally seen in fracture zones), but for it to be a hazard, you would have to be down range of the direction that the undersea mountain is shoved towards.

    In all cases, the undersea topology works to focus or defocus the energy from these events.

    A third potential source would be a continental shelf landslide. These tend to be more localized though, they are essentially point source events and the energy dissipates quite rapidly the further you are from the source. (1929 Grand Banks earthquake)

    Tsunamis are wave structures. Not that they are “waves” in what you see down at the beach. They are longitudinal waves. Compression events. But… by being an energy “wave,” some of the concepts of wave mechanics are at play. Specifically Near Field, and Far Field. In the Near field, an EM wave has not gained coherence and the energy is subject to local reflections and interference. The wave front looses energy as an ever increasing bubble. Once the wave transitions into “far field,” it travels as a coherent planar wave. At this point, energy loss is much less since the energy effectively travels as a beam. The issue with megathrust quakes, is that the tsunamis that the form, come into being as planar wave fronts since a large section of the sea-floor is lifted or moved as one unit. (or large units). Landslide or shelf collapse generated tsunamis are formed as point source events. They loose energy with distance until the wave transitions to “far field”

    What those distances are for tsunamis, I don’t know. For EM waves (radio, radar etc…) it’s about ten wavelengths.

    I think that the largest tsunami that England has encountered recently (think holocene) was from the Storegga Slide events.

    • Oh its far from being sanctioned by anyone familiar with the subject. Just that based on my experience (a completely different field) that’s the way I understand how they work. I’ve always tended to think of RF as a liquid. (which it’s not, but it helps to understand some of the strange ways that it behaves) Waves are waves… and it only makes sense that they have similarities in the way they behave.

      • Speaking of fluids, the Cruise Ship is getting worse:
        I guess they’ve had propulsion issues before.. there is a reason there was a “poop
        deck” the old square riggers.. I’d take a good Yankee Clipper over one of those
        things any day…
        Wife darn near had to hog tie me when I was offered a trip on the Lady Washington.
        a replica of Captain Gray’s ship. Mom’s family had sailors going back to the Royal Navy and Trafalgar …

  16. the gulf of Mexico is having a difficult time, first oil spills, still ongoing and now heaps of s..t stuff what a brew, wouldn’t do much for the wild life never mind the humans they caused the fracas in the first place….
    I have to much on my plate, so deferred things for tomorrow and think about it first

  17. Rumination here really OT……
    Thank goodness we humans are not all alike… I hunted for TGMccoy’s elusive cruise ship…. and found a link.
    The reason I am so interested is that I have a morbid fascinaton with disaterous cruises. A cruise holiday is my idea of hell on earth ever since I spent 12 days sailing to the West Indies from the UK on a small banana boat.
    We saw nothing once we left the Azores behind us the on the second night. The highlight before we saw land again (Barbados) were patches of Sargasso sea weed floating by. Seeing 50 or so passengers gazing with interest at drab khaki seaweed is a sad sight! Atlantic rollers are monsterous. Small banana boats had no stabilisers. I had a clear understanding of the discomforts those early settlers endured on their voyages…. except we did have good food. Unfortunately I wasn’t very hungry for the first couple of days…. some were confined to their bunks for 5 days and more. I wasn’t actually vomiting but I didn’t feel happy!
    I know these days the huge cruise ships are like hotels with entertainment…. But what is the good of that when stuck along with a thousand other people with seasickness added to Norovirus outbreaks? Inept capatains that sail ships too near rocks or icebergs. Power failures and exceptional wave size.
    I admit to an irrational phobia of being on large boats. Even cross channel ferries takes all my courage. I am happy as larry in small boats… but I come out in a fearful sweat as soon as I see metal plates and rivets!!!
    When I discovered my ex husband was planning a cruise for our 25th Wedding anniversary I understood then why I had left him two years before this date. Yes! He did know of my hatred of Large ships….!
    But as I said initially we are not all alike and I am sure to most people a holiday gazing at volcanic rocks and features. Camping in an earthquake zone or trekking to the top of a smelly, gaseous crater is not their idea of a heavenly Vacation!

    • I think a cruise is boring really, to many people in a confined space/time, no thanks, don’t like flying either, I am happiest driving myself, get nervous when another person drives, I always had a car full of kids/animals or both which takes a bid of planning ahead, but is fun and we got to see a lot of places around the country

      • i drive. Technically, not proffesionally, but not doing so would put me out of work. After a few hundred thousand miles under your belt, you develop a sence of how hazardous the people around you are. Not from watching them do stupid stuff, but from how hard it is to read them. Reading them is key to staying out of their way. When I can’t read them, I freak out and desparately want to get off the roads.

    • Wait, wait, Diana: Consider this thought.. what if all the thousands of people “enjoying” their holidays on those cruise ships would infect the holidaylocations we prefer? I am happy people who like being penned up on artificial swimming holiday islands in the numbers of thousands per ship, without any culture or anything which has been naturally growing over years, no nature, no geology, no landscapes. And whenever they set foot on land, it is behind some person holding an umbrella or a sign in the air, and they follow this guidemark like a heard of sheep. ( Yes cruise ships are my absolute horror too) BUT.. So, in order that all tose many thousand people bumping up and down on the oceans every year keep doing this and safe the really interesting holiday locations for us others,,,,,Cruises are nice and interesting 😉

      • Reminds me of the storm force 11 in a 10 storey ‘tub’ crossing the Bay of Biscay. Wheeeee!!!

        The view from the viewing lounge was only sea one moment and only sky the next – on deck 8 – and the singer in the bar went ballistic when one of the few hardy souls in there asked her to sing the theme song from Titanic….

        There was a lot of fresh plaster of paris on people’s limbs by the time we reached Spain.

        • LOL, Yep I remember Biscay in a Force 11 gale too. Not sure how many decks the ferry had but our bunks were down below the water and you could hear this terrific BOING! every time it dipped into the waves. Needless to say I abandoned my mother to her seasickness and went to an upper deck. I enjoyed a lovely quiet fried breakfast with my brother, no queues and great fun trying to keep the plate on the table. 😀

    • Tsynamis have been under-reported in the British Isles because there have not been any really huge (like the Lisbon earthquake) events since the development of coastal towns. The seaside town on a beach is a very recent development. Before then built towns were well back from the coast with only seasonal shacks for fishermen on the actual coast. Then the fashion for ‘sea-bathing’ came along and there was a boom in building. The older towns, like Southampton, Portsmouth, Hamble, Bristol, London etc. etc. were based on river estuaries – quite far upstream – or sheltered harbours. The urban areas have spread down to the open sea – eventually we will see whether they are able to withstand a tsunami.

      • Our Welsh beaches show parallel trees laid flat on the sand, said to be from 6,000 years ago, with the occasional huge antlered beast flattened amid the trees. Most are snapped just above the root, though some are up-ended. The sea level rose after that. The Isles of Scilly and Cornwall tell stories of their sunken lands, just as our local stories do. Maelgwn is blamed locally for leaving the gates open in the sea walls – after too much to drink – and the land of the ‘low hundreds’ was drowned.

        A little bit of me would like to see whether all the trees were toppled by the sea or whether perhaps there was a Tunguska type blast over Ireland which would cause the trees to radiate out….

        563AD is the year when the stories of dragons seem to be based on impacts and the Celtic cross brought to Scotland by St Columba, from Ireland, has such a star in its centre. Welsh legends then tell of Ireland being uninhabited,so I am curious about why such stories arose, and whether these originate in the bronze age from 6,000 years ago or are linked to the departure of the Romans when Britain became very cold, and nothing would grow, leaving the UK in the ‘Dark Ages’, and invaded by northern tribes who presumably were even hungrier..

      • 😦 Hopefully not in my lifetime! I live half a mile from the sea front and although the sea wall was raised around 20 years ago I wouldn’t like risking a tsunami, even a small one. GULP! I do sometimes dream of one hitting my town. 😦 😦

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s