Earthquake felt underwater

[bleach]

I did a couple of searches and did not find much about them...

This happened in Roatan last week. 10 minutes into the 1st dive of the day, about 45' depth. Everyone heard a loud boom, accompanied by what I would describe a shutter through our bodies. We all stopped and looked around at each other, and the DM asked if everyone was ok. After finshing the dive there was a little talk about what it was, I even asked a few locals if anyone used dynamite for fishing.

Living in Alaska, small shakers are somewhat normal, I never thought I would
experience one under water though.

Thanks to Carol for sending me the link.

USGS Earthquake Hazards Program: Earthquake Report

 

[scubamickey]

Very cool experience I'm sure. We're so desensitized to earthquakes here in Alaska (daily earthquakes) aren't we? Did anyone on the island feel the tremor?

 

[diver918]

Unique experience. My wife had asked me if someone diving would feel a nearby earthquake...guess i can answer her now.

 

[Doc]

They are heard quite often in Roatan. They center about 50 miles North into the Caribbean. Most people report a loud "crack".

Magnitude 4.5
Date-Time: Sunday, April 27, 2008 at 09 15 44 AM at epicenter
Location: 16.621°N, 86.237°W
Depth: 7.4 km (4.6 miles)
Region: OFFSHORE HONDURAS
Distances
110 km (70 miles) NNE of La Ceiba, Honduras
205 km (130 miles) N of Juticalpa, Honduras
300 km (185 miles) NNE of TEGUCIGALPA, Honduras
1185 km (740 miles) SSW of Miami, Florida

 

[akscubaduck1]

Unique experience. My wife had asked me if someone diving would feel a nearby earthquake...guess i can answer her now.

JAN. 27 08 1:01 pm
10 or 12 divers on the beach I'm half way through my solo dive when way off in the distance I could hear this rumbling, and it was rapidly get closer.

With in a few seconds it felt like I was in a ultrasonic cleaner.

I shook for a minute or so then past back into the distance.
After the dive I asked some of the divers on the beach about the earthquake nobody felt it.
UAF measured the earthquake at 4.03 MAG.
All and all a pretty fun ride.
But what if it had been larger???
Would I of been better off in the water or on the beach?
Terry
Dive Safe, Dive Often, Dive Prince William Sound, AK.

 

[rollerboi]

But what if it had been larger???
Would I of been better off in the water or on the beach?

Not a seismologist here, but I would think tsunamis would be of concern whether you're in water or on shore. You would definitely not want to get caught in a vertical uplift of water, I would imagine.

 

[scubadale]

Did you notice a change in behavior of the wildlife either before or after the shudder??

 

[diver 85]

One night in Dec 2000: Wife had fallen asleep already & I was about to @ our house on Roatan when we both felt a rumble of a few seconds(I naturally was aware of it more than her)...The next morning @ Inn of Last Resort(our son was DM'ing there & we were diving with them that trip), the earthquake was the talk of the boat---always wondered what it would have like UW....thanks for sharing.....

 

[bleeb]

But what if it had been larger???
Would I of been better off in the water or on the beach?

Not a seismologist here, but I would think tsunamis would be of concern whether you're in water or on shore. You would definitely not want to get caught in a vertical uplift of water, I would imagine.

I don't think it's that simple. During the Indian Ocean earthquake/tsunami, divers out at dive sites under or even on top of 30' of water didn't realize there was a problem until they got closer to shore and started seeing a lot of debris in the ocean. IIRC, at some reef dive sites a few miles (one?) off shore, water level variations were estimated at around 1' over 10-20 minutes. Tsunami waves pile up and break just like regular waves, only on a larger scale.

Maybe one of the oceanographers on here can explain more precisely, but I would guess the dangers to a diver of a tsunami wave depend on some combination of wave length and open ocean wave height (determined ocean depth and the magnitude of the fault movement), the local depth at the dive site and how fast the ocean bottom is rising as it approaches shore (including how far out the continental shelf starts, if the epicentre was beyond that). Depending on the bottom topography and depth, it could be really benign or it could be really ugly.

 

[seaducer]

Not a seismologist here, but I would think tsunamis would be of concern whether you're in water or on shore. You would definitely not want to get caught in a vertical uplift of water, I would imagine.

I didn't think tsunamis manifested in a "wave" until they were right on shore? Even the major one that wreaked havoc a few years back didn't appear that large on the videos I saw. I thought they were more a pressure wave, and that out at sea boats don't see them, but can feel the effects?

Or maybe I am just confusing a couple different shows I have seen...