Seconds to tens of seconds of advance warning re earthquakes.

=A0=A0=A0=A0=A0 =A0=A0=A0 http://www.elarms.org/index.php

US Geological Survey international earthquake logging and analysis site.
You can sign up to receive almost realtime report of the latest
earthquake events.
Much interesting stuff even if you are not that obsessed. (I'm subscribed :=
-).

=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0 http://earthquake.usgs.gov/

TSUNAMI EARLY WARNING SYSTEMS.

Tsunami travel at high speed in deep ocean - in excess of 500 kph if
deep enough. They reduce speed and increase height as depth decreases.
It is generally not appreciated that an eg 2 metre Tsunami is NOT a 2
metre wave - it's a 2 metre step change in water level travelling at
typically 40 kph. In Whangarei NZ the recent Tsunami was 400 mm high
on arrival. It almost sank large yachts at moorings and caused major
disturbances to small boats and some damage.



Advance detectors work by one of

- Deep ocean seabed shock / wave head differential detection

- Bragg scattering HF radar wave crest oscillation frequency variation
detection.
Reading between he waves shows this is still developing and not as
universally useful as it may some day be.

- Shallow water detection

None of the existing overall systems based on these methods works well
enough as presently implemented. The problems are more organisational
than technical.

The deep ocean buoy system was massively augmented after the 2004
Indian Ocean catastrophe, but the end result was not good enough to
assist in Samoa and Tonga a week ago. It was able to be, but was not
well used.

I'm idly tossing around ideas for a local scale system that would give
a community up to minutes of warning. This would not have been enough
in many cases in Samoa recently but will be much more ample in Pacific
areas in future because of the awareness and general appreciation of
Tsunami due to the recent disaster.
Nothing new technologically. A local system has the advantage that a
local community is=A0in control of whether the system is working and
what they plan to do about an alarm.

Several types of systems

=A0=A0=A0 http://www.envirtech.org/?gclid=3DCNn9iIWYqJ0CFSFRagodiFw2ig

Response to Indonesian tragedy 2004
They note that the quake to first wave time was 15 minutes and that
the quake was the second largest ever recorded.

=A0=A0=A0 http://www.sciencedaily.com/releases/2008/11/081110153720.htm


More

=A0=A0=A0 http://www.geophys.washington.edu/tsunami/general/warning/warning=
.html

NASA Bragg-line beam forming Doppler shift HF RADAR

=A0=A0=A0 http://adsabs.harvard.edu/abs/2007AGUSMOS34A..08T

HF RADAR paper

=A0=A0=A0 http://www.seaviewsensing.com/tsunami.pdf

CODAR Seasonde.
Arguably the market leaders.

=A0=A0=A0 http://www.codar.com/news_01_2005.htm



=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Russell

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