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Old 30-09-2018, 09:49   #1
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responding to tsunami in a marina

I'm curious to know other boaters thoughts on responding to a tsunami warning. In particular if you're a liveaboard or happen to be at the dock when the warning is issued. Naturally the time frame is important but I'm thinking one might have 30-60 minutes warning before the extreme waves arrive. At any marina that I've been in, at a high tide there is still about 5 feet or so of piling above the dock. But if the water rises over the dock piling which of course it would with a tsunami, then the docks would all be free to follow the path of the wave. Even if there was a way of securing the docks to the pilings the force of the wave action couldn't be stopped in my opinion.
So what to do? One option would be to abandon the boat and try to join the panicking masses and drive to high ground. Being a liveaboard this is home so it really doesn't sound like it would be my first choice if there were other reasonable options available. There are just under 1000 boats in this marina ranging in size from 24 feet to about 150 feet. The chance of having anything left when the waves subside are possibly and probably slim to nil.
So what about heading out to sea? I'm wondering how far from shore would be adequate to "comfortably" ride the waves like a roller coaster. Then what? You would have to have enough provisions and fuel on board to stay out for a number of days I would think. All the marinas and private docks would probably be destroyed in the area. After the warning was lifted you could head to a protected cove and drop the hook and then go to shore in your tender I suppose to join the chaos. At least you wouldn't have to be concerned about the cove being crowded with boats. All the boats that were there on the hook prior to the tsunami would now be up on the hard. I suppose you could travel 100 miles or so to try and find an unaffected marina to try and get moorage. But that would be hard to find at a time like that I would think.
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Old 30-09-2018, 10:08   #2
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Re: responding to tsunami in a marina

Two options, but you need time. Get a ways offshore quick if you are on the ocean. You need to get well out of shallow water.
Otherwise I'd just get to high ground.
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Old 30-09-2018, 10:14   #3
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Re: responding to tsunami in a marina

Get to high ground immediately, forget about the boat, chances are it’s history and you will be too if you don’t immediately get to higher ground.

Watch some of the Japan tsunami videos on youtube, boats trying to leave the harbor didn’t get far and were swallowed up.
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Old 30-09-2018, 10:39   #4
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Re: responding to tsunami in a marina

First off determine if there is any automated warning system along that coastline, probably not, or at least not an effective one outside Japan, and maybe some countries in SE Asia.

And if there is, what is the designed advance warning time?

I can see a Mac 26 with a 70HP getting into deep water pretty quickly.

But for 99.9% of us sailors, head for the hills, or the upper floors of the strongest concrete building around, kiss the boat goodbye
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Old 30-09-2018, 10:48   #5
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Re: responding to tsunami in a marina

A little history...
In the 1964 Alaska earthquake, a tsunami hit most of the US West Coast. In Fort Brag, CA, a fishing port, the Coast Guard went up and down Noyo river sounding a horn and waking crews aboard the boats. Boats were in rafts 5-6 deep. Early boats were well out and didn't even feel the effect of the tsunami. The tsunami came in gradually increasing surges until the big one. Later boats fought the surges to get out. The CG cutter, the last to get out, was just past the bridge and pushed back past the first bend by a surge, but then made it out. Of the boats left behind, some were carried a couple miles up river and their bones are still there today.
Crescent City only had 3 buildings still standing. In SF bay, another CG cutter traveling in a 40' deep parts of the bay had the props damaged when the water went out. Kodiak, AK was wrecked as were many Alaska ports. Some towns had to be moved to higher ground, ports rebuilt. Areas in the uplift that used to be channels are now too shallow except at high tide.

IF you have adequate warning go to sea.
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Old 30-09-2018, 11:02   #6
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Re: responding to tsunami in a marina

during the 2003 tsunami we left the anchorage in Koh lanta island thailand which was directly in the path of the tsunami, 30 minutes before the first waves hit ,we were about a mile offshore in 12 meters of water and watched waves breaking on shore,we felt nothing,apart from some swirling currents,and the depth sounder registering between 12m and 17m as the invisible waves passed underneath our yacht.

with sufficient warning i would head out to sea, on land i would aim to be at least 10-15 meters above sea level in any event where i could not leave on my yacht.
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Old 30-09-2018, 11:11   #7
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Re: responding to tsunami in a marina

Quote:
Originally Posted by Kenomac View Post
Get to high ground immediately, forget about the boat, chances are it’s history and you will be too if you don’t immediately get to higher ground.

Watch some of the Japan tsunami videos on youtube, boats trying to leave the harbor didn’t get far and were swallowed up.
It doesn’t always work out well for those who think they can get out to sea before the waves hit.
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Old 30-09-2018, 12:14   #8
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Re: responding to tsunami in a marina

How much warning will you have? How fast can you cast off and get to deep water? 150' of depth has been mentioned as a minimum depth to ride out a tsunami. Wave height is generally small until depth starts becoming shallow.
Clearly the tsunami warning system is inadequate in some parts of the world.... How could hundreds of people be at a beach party at Palau, unaware that a tsunami was imminent? Was there warning? Did they feel the earthquake? I don't think I would wait for the warning..... If I feel an earthquake I'm headed out to deep water...... or headed for high ground.
If you are a live aboard, and in an tsunami prone area, choose your location based on proximity to deep water..... If you are concerned about it.


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Old 30-09-2018, 12:30   #9
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Re: responding to tsunami in a marina

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Originally Posted by owly View Post
Clearly the tsunami warning system is inadequate in some parts of the world.
More like

it is only barely adequate in a very few places.

Great example of something that should be implemented internationally rather than via country-level governments.

Could just be a centralized SMS subscription, in addition to the local media / sirens + loudspeakers, etc
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Old 30-09-2018, 12:45   #10
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Re: responding to tsunami in a marina

Quote:
Originally Posted by john61ct View Post
More like

it is only barely adequate in a very few places.

Great example of something that should be implemented internationally rather than via country-level governments.

Could just be a centralized SMS subscription, in addition to the local media / sirens + loudspeakers, etc



The best warning is your own instinct.....If the ground starts shaking, cast off and get to deep water or head for the hills.............
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Old 30-09-2018, 13:16   #11
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Re: responding to tsunami in a marina

It is entirely possible to not feel the earthquake at all the locations the tsunami will affect. There are internet services which monitor tsunamis, so you could subscribe, and as long as you check all the time, you might be able to get out in time, but that is risky, too. Kenomac's suggestion to seek much higher ground makes more sense to me....

Now, like atoll, we have some friends who saw the water start to go away, and ran to their dinghy to get back to their boat, and went to sea, and survived to help out in the recovery. And another couple whose boat was damaged when the dock was washed out of the marina, who stayed on and repaired it. Another couple ran up a hill and hung onto a tree, and were high enough to survive, just barely. So yes, under some circumstances, one can survive. I do not believe that that tsunami was as huge as the one that struck Fukushima. Tsunamis vary in size and strength, and how the land shapes focus them.

Yes, we have left congested areas and headed for deep water, more than once, upon receiving tsunami warnings, and one commercial vessel stayed outside the reef in deep water for one in New Caledonia, which from our perspective was also a non-event. When you're out at anchor, and really deep water is available nearby, you might feel as if you were doing "the right thing", going out to sea, and it has proven so, in the past. But, there's no guarantee.

When we heard the warning in New Caledonia, if everyone in the marina and bays around Noumea had tried to leave for the deeper waters of the lagoon, it would have been extremely dangerous, with a whole lot of boats trying to get out a narrow opening to a safe place that would then have been crowded. The fact that we were the only boat that left might have helped us, if the tsunami had come into the lagoon. In that particular case, I suppose the land shapes and outer reef absorbed the force of that wave, before it got to Noumea.

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Old 30-09-2018, 13:32   #12
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Re: responding to tsunami in a marina

We were in the Galapagos when the tsunami from Japan came, but we had lots of warning, something like 12 or 13 hours. The harbour we were anchored in faced Japan and was roughly funnel-shaped so that is not good. At first the port captain broadcast a message warning about the tsunami and stating that no vessels would be allowed to leave the harbour. Within an hour or so he recanted on that and said that all vessels would have to get out. The other plus was deep (as in 10,000') is very close at hand, only a couple of miles. We went out about 3 hours before the forecast time and sat in the sun watching whales and did not feel anything from the tsunami. We went back into the harbour an hour or so after the warning ceased. The harbour was like a bathtub with currents swirling around from every direction. Made it hard to anchor because boats were facing in every direction. The wave had gone into the town a couple of blocks and a number of sea lions were killed when they were driven from a beach where they were sunning themselves against a retaining wall. If it happened at night a lot of them could have been killed.

Our circumnavigation was a bit of natural hazards world tour. When we were in Vanuatu there was a 7.1 earthquake at night when we were on a mooring. It did not disturb our sleep and there did not seem to be any tsunami effect. Anchoring in Pago Pago was difficult because there was a lot of tsunami debris on the bottom of the anchorage. The first four or five times we tried to get a hook we got tangled in stuff that fouled the anchor - like cloth feed bags and a lawn chair. Don't get me started on volcanoes or brush fires but it was instructive.
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Old 30-09-2018, 14:01   #13
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Re: responding to tsunami in a marina

It's a gamble to go out, so it depends on what you consider your odds are. They would need to be pretty close to 100% for me. In the video above, they would have been OK if they left 10 minutes earlier so with 60 minutes warning it would be a no brainer for me.

Where we are I think the wave would be broken across parts of the bay so we might need 4 hours to get into safe water. I'd head up the hill and watch.

We had a warning 4 or 5 years ago which everyone decided never eventuated, but it did arrive. We were out on the water and the tide had turned and had been running out for about 20 minutes when it started to come back in. It was just like a normal tide, nothing special otherwise and came up about 150mm (6") higher than the earlier high tide. Nothing was ever mentioned of it so I wonder if it was just particular to the local area and maybe only noticeable because of the phase of the tide and geography of the bottom. ?
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Old 30-09-2018, 14:43   #14
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Re: responding to tsunami in a marina

Thanks for your practical experience Atoll. I'm inclined to agree with heading to sea. The issue I have is time. Even though my cell phone is alerted with a tsunami auto alarm, if it comes at 2 am I think by the time I cast off I'll probably gobble up 15 to 20 minutes minimum. My 40 ft. boat has a top speed of about 18 knots. I'm on the inside of Vancouver Island BC Canada, at the south end. It's about 40 miles to the mainland. However there are a few large island to get past before open water. I'm thinking those islands could possible create a venturi effect. I'm not checking the charts right now but I'd say 10 miles out would get me clear of having islands on both sides of me and comfortably in open water and I could achieve that in 30 minutes. Lots of depth in the waters around here even close to shore so that wouldn't be an issue. It's interesting and encouraging to know that only a mile off shore the waves were rolling and not breaking in your instance Atoll.
As for earthquakes, I don't think I'd feel any significant earthquakes while on the boat. There has been a couple mild ones that people have felt on shore recently, that I didn't feel or even sense.
I remember that same earthquake you mentioned Lepke, in 1964 which created a tsunami travelled up the Alberni Inlet on the west side of Vancouver Island and created disastrous results
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Old 01-10-2018, 00:42   #15
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Re: responding to tsunami in a marina

The last tsunami warning here just a few folks headed out. Mostly folks who commercial fished, and lived aboard. We contemplated it, but high ground is less than a mile from our live aboard... Including the .3mile walk to the top. You just pray that the quake was far enough away to make it to the car.

More disturbing was the fact that they shut down the cellular data during the warning. Basically no coms. Even calling local wasn't reliable. Stressful. I really need to pick up that baofeng handheld radio I've been eyeing... Especially since the FCC is frowning on them now.


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