INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Offshore water depth and tsunami

Offshore water depth and tsunami

(OP)
Can anyone point me to general guidelines on how far offshore you'd have to go for the following to be comparable or less than conditions in a 100-year storm:
(1) Change in water depth due to tsunami
(2) Currents associated with surging / retreating crest
I have found recommendations that boats move offshore to waters deeper than 100m and even 400m, but no technical guidelines.

RE: Offshore water depth and tsunami

Just head away from shore, and only turn around when you hear news reports that the tsunami has arrived.  If you're far enough offshore, you won't even notice it go under the boat.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Offshore water depth and tsunami

Tsunami height varies according to dozens of factors, so it's very difficult to guess at.  Further out you are, the lower the delta.  Wave height varies by shore line shape, by approach depth profile, by earthquake intensity, by the way in which the earthquake adjusted the ocean floor profile, etc.  It just depends.

Same can be said for storm surge.  Surge varies by how low the central pressure of the hurricane is, by whether you're on the leading or trailing side, by the speed with which the storm tracks over land, and also by some of the same geometry factors above, like shore line shape and approach depth profile.  The big one for hurricanes is the delta between the central pressure of the storm and the surrounding air, which tends to squeeze surrounding water towards the center of the hurricane.  

"100 year storm" is a terrible thing to try and compare to, because the 100 year storm is a measure of rainfall depth over an arbitrarily chosen duration, which is only loosely correlated with the surge.  But even if it wasn't, I seriously doubt you find the data to answer your question anywhere, unless it's neck deep in someone's phd thesis.

Go watch some youtube videos.  There was a fantastic one of the Indonesian tsunami that I saw a while back taken from a guy on his sailboat, anchored up in a cove.  He and his buddies in the anchorage all came above decks to check out what was going on as they swung at anchor, and I remember him filming his anchor rode.  Looked to be about a four or five knot current going under his boat.  Then he panned the camera shoreward and caught the wave as it hit the village.  I can't seem to find it now, but if I do later I'll post a link.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

RE: Offshore water depth and tsunami

(OP)
Thanks to all.  Sounds like a regional tsunami height model is the way to go.

RE: Offshore water depth and tsunami

If you've followed all the tsunami videos from Japan, you can see where some places had intrusions on the order of miles, and others places where the intrusion was tens of miles, due to localized terrain constrictions forcing the water to flow along natural terrain features and riverbeds.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close