Nick, (and all)

Thanks for your reply.

If I understand you correctly, you are looking for evidence that shows that 
an actual association between a lone seaquake and a stranding, as opposed to 
5 or 6 seaquakes preceding most mass beachings.

Often I find only one or two seaquakes upstream.  A stranding I researched 
off the coast of Tasmania comes to mind.  I had two suspicious earthquakes 
and no evidence to guide me to which might have done the most damage.  I 
contacted Australia GeoScience and ask them if there was any way that one of 
their experts might be able to tell me which earthquake generated the 
greatest LF pressure disturbances in the water column.  They sent me two 
spectrographic images recorded by the underwater listening station near 
Perth.  These images made it very clear which quake had the greatest 
potential for injury in whales.  Still, both events were strong enough to 
have caused the stranding depending of how close the pod was to the 
epicenter and how deep each whale was when the seaquake waves crisscrossed 
over their bodies.

One would naturally think the deeper the pod, the more likely it is that 
they are injured.  But this is not true.  Barotrauma is far more likely in 
whales near the surface because the percentage of volume changes in the head 
sinuses are much greater than at shallow depths.  Said differently, deep 
diving whales are actually safer during a seaquake if they head toward the 
bottom simply because the percentage of change in the air volume is less the 
deeper the whale dives.

This brings up evolution as an important consideration.  Whales and 
seaquakes have co-existed side-by-side for millions of years.  Surely the 
whales have made evolutionary changes to seaquake pressure waves.  The 
question is: did evolution hit a snag it could not overcome?  The greater 
the percentage of pressure changes underwater, the more potential for 
injury. In other words, as the whales evolved to dive deeper and deeper, the 
more vulnerable they became to barotrauma at shallow depths.  This brings up 
another question.  Surely the whales have evolved defenses maneuvers against 
a pending earthquake.  If this move involves detecting geomagnetic precursor 
signals and quickly heading toward the safety of the surface, then those 
pods that are caught at 50 meters are in far more trouble than they would 
have been if they stayed down at 300 meters.

Thus, there will likely never be a way to pick between several earthquakes 
as to the exact event that caused the stranding because, even if you know 
the most violent quake, you will never know how close and how deep was the 
injured whales.

In my opinion, the fact that there are often more than one seaquake to pick 
from is supporting of the theory and not degrading.  Said differently, there 
is a very strong positive association between seaquakes along the mid ocean 
ridges and mass stranded whales. On the other hand, when there are no 
seaquakes upstream from the stranding beach, then you might say the seaquake 
theory suffers credibility.  But when seaquakes are plentiful, credibility 
of the seaquake theory gets a boost.

This also brings to mind seasonality of potentially harmful earthquakes 
along certain mid ocean ridge segments.  For example, rarely is there a 
harmful seaquake upstream from Cape Cod during March thru September.  This 
couples perfectly with the fact that strandings are rare on these beaches 
during this period.  The same holds true for mass stranding in Australia and 
New Zealand.  Damaging earthquakes occur 20 times more often during the 
stranding season than during the off season for such events.

I hope this helps you understand my work better,

Warm Regards,
Dave Williams


----- Original Message ----- 
From: "Nick Tregenza" <[log in to unmask]>
To: "David Williams" <[log in to unmask]>
Sent: Tuesday, January 05, 2010 8:29 PM
Subject: Re: [ECS-TALK] Comments on recent pilot whale strandings on eastern 
coast of Canada


>
> David,
>
> I'm not questioning your ideas about the mechanism by which seaquakes 
> might cause strandings, but looking for evidence that shows that there is, 
> or is not, an actual association between seaquakes and strandings, as 
> opposed to a situation in which there are enough seaquakes for there to be 
> one or more preceding most strandings, even when they are caused by 
> something else...
> Such tests have to be done blind (you don't know which dates are correct) 
> unless every step of deciding if this was or was not seaquake, or a 
> stranding, is defined by precise rules that could be applied by a 
> computer.
>
> Hope that explains the question.   If it passes such a trial the seaquake 
> theory could become accepted.
>
> best wishes,
>
> Nick
>
>
>
>
>
>
>
> David Williams wrote:
>> Nick,
>>
>> I'm very sorry, but I do not understand your questions.
>>
>> But I can give you a few observations that might help you understand my 
>> work.
>>
>> (1)  The basis of the seaquake theory is that a pod of whales are on a 
>> feeding dive along a mid-oceanic ridge system when a earthquake errupts 
>> in the seafloor below them.  The verticial dancing of the rocky bottom 
>> acts likes a giant piston, generating potent changes in the surround 
>> water pressure.  The sudden increase/decrease in hydrostatic pressure 
>> exceeds the whales' ability to adjust and causes barotrauma in the 
>> pertygoid sinuses. An injury of this nature disables echonavigation and 
>> prevents diving and feeding due to intense pain.
>>
>> (2) Without a sense of direction, the pod swims downstream in the path of 
>> least resistance.  Oceanic sharks dog the wounded whales like a pack of 
>> wolves trail a herd of reindeer. The whales become too weak and stress to 
>> avoid a stranding after ~25 days lost at sea without food and fresh 
>> water. The current is then able to carry them ashore where they strand, 
>> usually at night.
>>
>> (3)  To determine the earthquake that might be responsible, one must look 
>> back upstream from the beach.  While tracing the flow of the current, one 
>> should start looking for a dangerous earthquake that might have occurred 
>> along the way.  One should also be looking for a known habitat for the 
>> species in question somewhere along a mid-ocean ridge system.  In most 
>> instances, when you back trace the current to a known habitat, you will 
>> find 3 or 4 earthquakes of ~5 magnitude or better.  The focus of these 
>> events are usually less than ~10 km deep in the seabed.
>>
>> (4) Not all magnitude 5 earthquakes produce dangerous seaquakes. 
>> Earthquakes with predominate horizontal movement do not produce dangerous 
>> pressure changes because motion horizontal to the surface produces a 
>> shearing action.  The rocky bottom simply slides through the water like a 
>> paddle turned sideways.  Only vertical thrusting produces dangerous 
>> seaquake waves.
>>
>> (5)  Magnitude of the earthquake is not the controlling factor.. 
>> Seaquakes (pressure waves in the water) are generated by rapid vertical 
>> thrusting in the seafloor.  The intensity of the seaquake wave depends on 
>> the speed of the vertical thrusting, not the magnitude.
>>
>> (6)  The deeper the focus the earthquake, the less likely it is to injury 
>> whales.
>>
>> I hope this helps.
>>
>> Warm Regards,
>> Dave Williams
>>
>> ----- Original Message ----- From: "Nick Tregenza" 
>> <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Tuesday, January 05, 2010 6:21 PM
>> Subject: Re: [ECS-TALK] Comments on recent pilot whale strandings on 
>> eastern coast of Canada
>>
>>
>>> David,
>>>
>>> Have you tried looking for quakes for a set of strandings that you've 
>>> never examined previously in which half have had their dates moved by a 
>>> year?
>>> I'm asking because it's an interesting hypothesis, but without knowing 
>>> how often explanatory quakes are available by chance within the huge 
>>> circles of influence you allow it's impossible to know whether it means 
>>> something or nothing at all.
>>>
>>>
>>> Nick
>>>
>>>
>>> -- 
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> Nick Tregenza
>>> Chelonia Limited
>>> 5 Beach Terrace
>>> Long Rock
>>> Cornwall
>>> TR20 8JE
>>> UK
>>>
>>>
>>> www.chelonia.co.uk
>>> C-POD software  www.chelonia.co.uk/cpod_downloads.htm
>>> [log in to unmask]
>>> tel +44 1736 711783 mob 07871 393 285
>>> fax +44 (0)8700 554967
>>> _________________________________________________________________________
>>>
>>> Homepage www.jiscmail.ac.uk/ECS-TALK
>>>
>>> How to join/leave the ECS-TALK list, how to obtain a Listserv Password,
>>> how to post a message to the list, what to do when going on Holiday?
>>> http://www.jiscmail.ac.uk/help/using/quickuser.htm gives the answers to
>>> these and more questions!
>>
>>
>
> -- 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Nick Tregenza
> Chelonia Limited
> 5 Beach Terrace
> Long Rock
> Cornwall
> TR20 8JE
> UK
>
>
> www.chelonia.co.uk
> C-POD software  www.chelonia.co.uk/cpod_downloads.htm
> [log in to unmask]
> tel +44 1736 711783 mob 07871 393 285
> fax +44 (0)8700 554967 

_________________________________________________________________________

Homepage www.jiscmail.ac.uk/ECS-TALK

How to join/leave the ECS-TALK list, how to obtain a Listserv Password,
how to post a message to the list, what to do when going on Holiday?
http://www.jiscmail.ac.uk/help/using/quickuser.htm gives the answers to
these and more questions!