PSN-L Email List Message

Subject: Re: "S" Shear Waves and Water bodies Like Lakes
From: Geoffrey gmvoeth@.........
Date: Tue, 03 Apr 2012 02:28:07 +0000


Many years ago, While Aboard a large ship
(USS Long Beach CGN9 or USS Bainbridge CGN25)
while  moored to a pier
Either in Long Beach or San Diego
(Cant remember which) I too felt an intense bump
and was immediately expecting a collision
or General or some other kind of alarm
which never came only to learn later from
the radio news it had been an EQ.
It felt like something had hit the ship.

I have heard such reports are logged
in old sailing ship logs when they had no
idea it was an EQ.

They simply logged it as one of those
unknown things of the Ocean.

Think of the Energy,
Even if 500 sailors jumped at the same time
on the main deck, up and down,
you would not feel what i felt that day.

But this idea still does not answer my question.

I think a body of water can act as a pendulous mass
and stay at rest while the earth moves round it
in the case of "S"  waves. Only at the shore line,
should disturbances, first be noticed.
if your standing on the shore of a great lake
you might get instantly covered with water if the "S"
motion was great enough, but, not because the water moved.

geoff



On 4/2/2012 8:46 PM, Dave Nelson wrote:
> Hi Geoff
>
> If you are sitting in on a lake or other body of water, you will NOT
> feel the
> shear (S) waves. You WILL feel the pulse of the P wave as it passes
> through.
> There's been a couple of incidences in New Zealand some years back, '80's
> and '90's, of guys in boats both on lakes or at sea close to the
> shoreline ( within
> a few 100 metres or so) They both described the passage of the P wave as
> a thud
> as tho the boat had run aground. They didnt feel the shaking of the S
> waves.
> They were also within ~ 100 km (60miles) of the epicentre. One quake was a
> hi M6, the other was a low M7
>
> cheers
> Dave N
>
> At 04:52 PM 2/04/2012 +0000, you wrote:
>> Hello PSN;
>> Looking for comments here:
>> When a body of water such as a lake is hit by shear waves
>> does anyone know for sure what will happen ?
>> Like,
>> Do water waves form at the perimiter and converge at the center.
>> Like, since, S waves do not travel through liquids of any kind ?
>> Has there ever been witnesses to such a thing ?
>> I was just laying here as I woke from sleep
>> thinking about this.
>>
>> When I looked at an EQ in three dimensions using a computer
>> program I saw a kind of orbital motion of the ground about
>> the mass and no clear cut steady wave like activity.
>>
>> Regards,
>> geoff
>
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