Tsunami How-To ?

[sarafina]

Originally Posted by teneicm

I think he may have meant 8" (inches instead of feet)....

If it was the one in the early '90's it was so small it could have only been like 8", and on our coast 8" isn't even a blip on the radar. It depends on your shore line... even 8 foot waves wouldn't be much of a problem on most of the California coast. We have cliffs that tower over the beach up and down the coast.

That little one was pretty funny... a mob of people in San Francisco heard the tsunami warning and promptly flocked to ocean beach to watch for it.... up at the cliff house there was a rockin party and when the time came and went someone called out "ok, I am officially designating 'This One' the tsunami" so everyone could raise a glass and toast the event.

conversation overheard between two cops with bull horns warning people off the beach;

Young cop; "Don't they get this is possibly dangerous??"
Old cop; " Yep, but this is San Francisco."


yeah yeah... don't ask how I know all this.

[cdennyb]

If you're throttled up and headed straight away too deep water, when the water went outward wouldn't you start really hauling buttt as compared to the land around you but still making 8knots or whatever in reference to the water?
I bet if you were lucky you could see some really good numbers on the GPS to show your friends! Asumming you made it out alive.
LoL

[Beverly Stayart]

The ability to predict these in advance has not improved.

[Reality Check]

On the "other" side of the world.... Just off Grenada Kick'em Jenny and Kick'em Jack are two but possibly the same Active submarine Volcano's that have many people concerned about what ifs and the possible Caribbean tuimani.... in an area with out much in the way of a warning system for these type events. Also not much warning about gas eruptions these two have that could be bad news even for the boats that honor the no sail areas around them.


Smithsonian Institution - Global Volcanism Program: Worldwide Holocene Volcano and Eruption Information=

Some vulcanologist think there may be a danger of Grenada being totally destroyed... not in the way that physical damage could occur to island built up structures but the entire island itself as in gone... and with a tidal wave that may could potentially affect many of the Caribbean islands.

Something to think when sailing around Grenada and reminds me of the Jimmy Buffett song Volcano which I guess could be about the same place???

[Tropicyachty]

Tsunami Devastates American SamoaSeptember 30, 2009 – American & Western SamoaYesterday at 6:48 a.m. local time, an 8.0-magnitude earthquake shook awake American and Western Samoa. Several minutes later — just enough time to allow folks to make their way outside to talk with their neighbors about the temblor — a tsunami swept the islands, killing at least 119 people.Aussie singlehander Nick Jaffe of the Contessa 26 Constellation — who was featured in the July issue of Latitude — is in Apia on Western Samoa. He reports that "the marina and Apia Harbor began to dry as the water went out to sea. Several boats in the marina hit the ground but I don't think there was any damage. I went to Aggie Grey's hotel until things calmed down."John Neal and Amanda Swan-Neal of the Port Townsend-based Hallberg Rassey 46 Mahina Tiare were also in Apia when the tsunami hit. "Amanda and I were on our morning run when the street started shaking," said John. "Minutes after we arrived back at the harbor, the civil defense sirens went off and the police directed everyone to run for the hills. The water in the marina started to really surge, dropping lower after each surge in. We followed the moving mass of people, cars and trucks up the hills. The smart yachties headed for Aggie Grey's hotel, where staff welcomed them and sent them to the top floors. They had a great view of the harbor going dry for several hundred yards out."About 300 miles south, in the Vava'u group of Tonga, Eric and Emmy Willbur of the Pt. Richmond-based Flying Dutchman 37 Nataraja said that their anchorage of Kenutu saw some "rather interesting tidal flows with 3- to 4-ft standing waves breaking over the reef. There were reports of major tidal influences at other anchorages with water going out suddenly and dropping as much as 10 feet, then coming back in very quickly. Here in Vava'u, we've only heard of small docks being washed away — no loss of life or major damage."David Tyler and Fran Flutter of the UK-based Tystie, who were featured in February's Latitude when they passed through the Bay, were in nearby Neiafu Harbor and report experiencing a rise and fall of just a couple feet. "No damage apart from some jetties being washed away," they said.By far the most comprehensive report came from Puddle Jumper Kirk McGeorge, who is cruising with his wife Catherine and their five-year-old son Stuart aboard the USVI-based Hylas 47 Gallivanter. McGeorge called us via Skype from Pago Pago on American Samoa shortly after the tsunami devastated the island, then sent the following report:"This morning we were shaken awake by an earthquake which seemed to have no end. We were aboard Gallivanter and side-tied to a big concrete dock. After the rude awakening, Cath and I walked across the dock to chat with a few of our fellow sailors, one of whom said that he's just done a Google search on 'recent earthquakes' and said that it measured in at 8.1 and the epicenter was only 120 miles southwest of Pago Pago on the southern side of the island. "We returned to Gallivanter and I verified what he said. Just as I was considering the ramifications of that little fact, all hell broke loose. Our boat was on the move! I started the engine and dashed up on deck to see what was going on. I witnessed the water around us rapidly dropping — rapidly! In the blink of an eye, we were on the bottom and the boat was falling away from the dock. Three of our big docklines popped and we fell right over into the mud — the entire basin in which we had been floating only moments ago had completely drained! People were screaming! "The water came flooding back in at an even more alarming rate, and the next thing I knew we were floating directly above the dock. We were over the concrete slab and drifting toward a young lady we knew from another boat, who was up to her chin in swirling water and desperately hugging a power pole. I told Cath to cut the two remaining dock lines with our serrated bread knife and to be quick about it! "Right as I put the boat into gear, we were somehow washed back off the dock and into the basin as I advanced to full throttle. We accelerated through a floating debris field of floating docks, fuel drums, sinking boats, a shipping container and a barnacle-encrusted wreck, all of which were spinning in the torrent of rapidly dropping sea level. It was absolute mayhem! As we steered out toward the deep water in the center of the harbor, I looked over my shouder and saw what appeared to be a waterfall pouring off the dock and shore beyond. Not one of the dozen vessels remained at the dock. All were underway in a matter of seconds — with or without crews aboard. "We motored around in the middle of the harbor watching the waves of floods and ebbs while wondering about aftershocks and our fellow cruising sailors. As we passed one of our neighbors, she shouted to us that her husband had been washed off the dock as they were trying to get away. She was alone and seriously concerned. We found out later that he was confirmed dead. Other boats broke free from their moorings and anchors in the initial seismic waves, and many were driven ashore or driven under by loose tuna boats. "After about three hours, we felt it was finally safe to return to the dock. We were the first to go back in so we started untangling lines and helping others get back alongside the concrete dock. All the storefronts along the water are destroyed, roving mobs of kids can be seen looting, the fence around the dock is gone, and every boat on stands in a nearby boatyard was washed away. Big fishing boats are now in parking lots across the street. Absolute destruction is seen everywhere along the shore. "Phones and power are down but we got back online right away. I immediately went back to the recent earthquakes website to see if things had calmed down in the center of the earth. A number of aftershocks as strong as 6.0 were recorded over the following few hours — but thankfully no more wave action has been noticed. We've been making Skype calls to our families and letting others use the computer as well to phone home. "Online news reports say that the earthquake lasted three minutes and the highest flood rose 25 feet above normal! Most fatalities occured in and around the harbor where we live. Boats are battered and nerves are fried. One friend wound up on his boat nearly 1,000 feet inland after breaking from his anchor and sailing right down Main Street, taking power and telephone wires down with his mast! Some people lost everything, including their lives. We came through remarkably well with only minor damage sustained to our toerail when the docklines parted and to our fender basket, which was the only point of contact with a drifting wreck. I believe our hull, keel and rudder suffered no damage from the wildest boat ride I've ever been on. We're all okay — and very lucky." Residents were stunned at the destruction of the wave action. © 2009 Fili Sagapolutele This morning, a 7.6-magnitude quake hit Sumatra, Indonesia — along the same fault line that spawned the devastating 2004 quake that left 232,000 dead. Though more than 1,000 are feared dead, and thousands more are caught in the rubble, a tsunami warning has been lifted.

[Lodesman]

Originally Posted by Tropicyachty

The smart yachties headed for Aggie Grey's hotel, where staff welcomed them and sent them to the top floors. They had a great view of the harbor going dry for several hundred yards out."

This should say the "lucky yachties". Apia is on the north side of the island and the epicentre was south, so they didn't get it bad; but at the time of the event they had no idea. Aggie Greys is across the street from the harbour and fully exposed; yet there's a mountain less than 1 km away. The police said "head for the hills" - they should have done so.

[SkiprJohn]

Our plan was to get underway with club boats as soon as we heard there was a wave generated. We got the news 2.5 hours after the earthquake that there was an insignificant wave generated so we relaxed. It would take us about 1.5 hours to get to the 100 fathom mark and no matter what sort of wave was generated we would not notice it at sea.
The answer is get to sea if you have time. If you don't have time just stay away from the ocean. I love boats but they are not worth your life.
regards

[roger.waite]

Originally Posted by MarkJ

Insurance? Wouldnt that be an Act of God? Is it covered?
M

First you ask them which God did this to you ...
Then you do them for imposing their religeous beliefs ...



P.S. must stop playing with the new animated icons ...

[Cheechako]

8' or 8"..... at sea neither would not be a problem. reportedly they are just a long swell at sea.... the shore makes them steep and break...

[Paul L]

Originally Posted by MarkJ

...At least theres a few minutes to work out a good plan while under way!

Thoughts?

Mark

From my armchair point of view I tend agree with you that best plan is to head out to deep water as fast as possible. This is clearly a theory only proposition. The only known death of a cruiser from the Samoa tsunami was someone who tried exactly that and was washed off the dock. Everyone that headed up to the hotel seems to have been OK, along with the couple of boats that actually got out of the slips. I wonder how many of the cruisers that went up to the high ground remembered to take their ditch bag with them?

Paul L

[MarkJ]

Originally Posted by roger.waite

First you ask them which God did this to you ...
Then you do them for imposing their religeous beliefs ...

...

Ummmmm I thought God was the same. Its just 3 differnt avenues to the same place.

But lets not get this foum into a religous argument! LOLOL we would be here all day!


(one path has more virgins, one path you can't touch them)

[Tom Hildebrandt]

The three major lessons learned from the Indonesia/Thailand Tsunami were

First that that if you were on your boat at anchor in less than 40 feet of water, slip the anchor and head to the deeper water, those who tried to raise the anchors or who could not make an instantaneous decision to get out to deeper water were in trouble. Those in marinas who were on their boats did not have time to manuver to vacate the slip, much less get out of the harbor..

Two -- Almost every boat anchored in over 40 feet had no real problems, those in 30 feet had some issues but generally did okay, anything less than 30 feet, lots of problems. So, in most marinas and shallow anchorages, lots of problems.

Three If you were not on your boat, you had best get to the hills, you were just one of "the others"

Part of the problem with heading out to sea is that you are almost exclusively relying on motoring, and once the first surge has come and done its thing, there is a significant chance of the propellor fouling, salt water cooling flow failing and just general damage from debris. Even if none of the above are a factor, we still face the problem that most sailboats will not be able to make any significant progress against the incomig current. At best we can hold our own when there is the surge, and inbetween surges, we may be able to make some headway.

My plan is to be anchored in 30+ feet of water, if I have a chance to leave well before the first surge, or otherwise I will use engine power to help keep pressure off the anchor. After the first surge has just past. if I did not drag, I will stay put and hope the second wave is not muchworse than the first. If I dragged, or otherwise felt there was an issue, I woul slip the anchor immediately and head out before the wash from the first surge brought more debris.

It will be interesting to see how the real life stories of this tsunami match up with the Indonesian/Thailand one. I am ready to be flexible in my plans!

[S/V Willow]

A friend of ours was anchored off outside the marina at Langkawi, Malaysia when the boxing day Tsunami hit and, of course they had no notice of the impending disaster. They were flung over to 90 degrees and then popped back upright. They turned the engine on, dropped then anchor and headed nose first into the following wave and then stayed out in deep water for the third one. No damage done other than the loss of a pair of shoes and a little heart murmer! Langkawi marina was devastated.

They weren't anchored far off and certainly not in deep water and managed to survive, although a little ruffled. Mark is right - have a plan B or exit plan and head for open water as soon as possible. It is the proximity to shallow water and land that makes the wave increase in height and velocity and, in the case of Langkawi, if the water is also funnelled through a small opening it becomes devastating. I believe that if the shake is substantial enough to wake you - take heed and put the pedal to the metal (so to speak).

[hoppy]

Originally Posted by yacht_moondust

I believe that if the shake is substantial enough to wake you - take heed and put the pedal to the metal (so to speak).

If you are on a boat at anchor would you feel any shaking? I would have thought that the water would isolate you from any shaking?

[Tom Hildebrandt]

Hi Moondust!

Were your friends anchored off the south or the north side of the Royal Yacht Club at Langkawi? As I recall the depth of the water south where most boats anchor is around 20 feet and then shallows fairly quickly about 40 meters from shore.

Just as you say, when the water starts to shallow up, that is when the wave really builds. And if you have a bay where there is a larger opening and then the wave get funnelled to the beach in one spot that is when you get the huge wave and the huge shore damage. That is what happened at Phi Phi Don in Thailand and i several of the west coast bays. In some of the spots in Malasia, like Telaga Harbor, the boats out in the anchorage behind the two islands where most of the water depth is 20 feet or so, managed allright, but many dragged anchor as the rise in water shortened scope and that combined with the eddies caused most to drag anchor. But sa few managed to slip or raise anchor before the second wave and got out. Most of the boats outside the harbor itself only suffered minor damage, typical of boat that drag into other boats. Except close to shore, the waves were a wall of foaming water bout a meter high. Inside the harbor, where there was only a narrow entrance, there was no wave to speak of, but the videos showed was just a rapidly rising surge, over ten feet, but no real wave. Since the entrance is over to one side of the harbor a conter clockwise circulation of perhaps 8-10 knots was created on each surge,, and then when the surge left left, it reversed direction, sort of like a wasing machine. As the pontoons came loose with the boats still attached, they joined with the boats that dragged all the moorings and almost everything became one giant clump of debris that got churned around, eventually some of the debris(boats and pontoons) actually got sucked in and out out of the harbor entrance Since this happened three times, things were really mixed about. The problem was that the one or two boats who actually got power on in the harbor could not do motor forward against the current, and were hit by all the debris. Most boat in the harbor had lots of damage, but it was caused not by the wave, but by being ground up by the other boats and pontoons.