7.3 Earthquake - What should I have done?

[LWinters]

I am currently anchored in 15 feet of water at French Harbor on Roatan, Honduras. The night before last we had a major earthquake several miles offshore to the north of us. The strange vibration woke me from my sleep and extreme confusion set in. I recall asking the girl next to me, "what is that"? The look on her face instantly said, "holy hell if you don't know why in the hell are you asking me"?

After a few seconds the noise faded and I easily resumed my slumber seeing nothing out of place. It was only the next morning that we realized what had happened.

Tsunami. That was the fear that began welling up in myself and the other islanders. All ferry traffic was halted, but I kept thinking that staying put was crazy. Only a ship at sea is safe where tsunamis are not felt in the deep water. Close to shore they are sitting ducks for the massive waves.

About the time this was all registering the authorities lifted the warning with the statement that any potentially affected areas would have already been hit.

So, if you are on your boat and your region gets hit with a massive quake is proper protocol to haul ass to deep water?

[peptobysmol]

deep water or high ground. But i'm guessing if you felt the quake your in your boat... your best bet is to assume the "worship" position

[noelex77]

Given the threat of a Tsunami I would get myself into deep water and heave to, but despite all its destruction, the Tsunami wave is surprising small and I suspect the risk of damage from the wave when anchored in 15 feet of water is small. A greater risk may be from the water rapidly receding and grounding the boat. If tied to shore or pontoon I would defiantly move.

[Selkirk]

It may help to remember that often before that actual wave hits, the water recedes.....looks like the tide just suddenly went out - way out.
So I'm thinking, yeah, if you suspect you just felt an earthquake, pull it up and motor out to sea.

[bacampbe]

I can't claim to know much about tsunami, but if one resulted from a quake that was centered only "several miles" from you, I think the wave would be on you before you could do much.

[Selkirk]

Originally Posted by bacampbe

I can't claim to know much about tsunami, but if one resulted from a quake that was centered only "several miles" from you, I think the wave would be on you before you could do much.

You're right. I got to looking around for tsunami information and a lot of what I found was surprising - at least to me. Here's the website:
Tsunami- EnchantedLearning.com

[LWinters]

Nice link Selkirk. The epicenter was less than 100 miles from here which means at a velocity of ~ 600 mph I would have just under 10 minutes from the time I felt (mostly heard) the quake to the time the wave was on us.

It's been blowing 20 - 25 every evening so I've got almost 10:1 scope out. With my old manual windless I'd have a nice view of the receding water and first run up from the bow of the boat as the last of the anchor chain and anchor were being secured.

Awww the risks we take to live the dream. Never read anything about that one in any of my books.

[Valiente]

Sailboats in the vicinity of the Christmas quake in Sumatra a few years back reported a slightly bigger swell, but we all know what happened near shore. Not all earthquakes cause tsunamis, and the worst tsunamis are sometimes not earthquake-related at all. A huge underwater landslip, like the one forecast to slide a chunk of a Canary Island down to the abyssal plain some day, could create a huge tsunami pointed at the east coast of North America. After the initial very impressive "splash", the sheer depth of the ocean would disguise the forces involved until the 150 foot rollers came ashore...eek!

Being so close and in just 15 feet of water, you got a "free ride" with no harm done, which was lucky indeed, as a tsunami at that depth would've likely put you ashore or capsized/crushed the boat.

I find it interesting that even on a boat you describe the same disorientation and confusion noted by people on land, even though the water must have mitigated somewhat the vibrations felt on land. Thanks for sharing this.

[mccary]

Being a Chesapeake Bay sailor I have never experienced an earthquake and never a tsunami, but my understanding of tsunamis is much like any large ocean wave breaking on the beach. In the open (read deep) ocean the wave energy extends down in the water but as the wave approaches shore the water depth becomes shallow and that energy has to go somewhere so it builds up high above the water and hence you have a breaking wave on the beach. The energy of a tsunami is much greater and hence makes a much taller wave breaking on the beach. And just like the normal surf wave breaking on the beach the water recedes just before the wave builds. So, if you want to get an understanding of a tsunami just shrink your perspective down and stand on the beach and watch the large ocean rollers building and breaking on the beach.

I don't think being anchored in 15' of water would have been sufficient to be safe from the effects of a tsunami, I think it would have taken off shore depths 150' + depth. But I am not an expert on this so I could be completely wrong.

[sailak]

Lituya Bay Alaska, 1958 ---- 500m wave.

Biggest tsunami | Biggest Wave | Lituya Bay Tsunami