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Tsunami warning

PostPosted: Sat Feb 27, 2010 5:01 pm
by Norman
http://wcatwc.arh.noaa.gov/events/eventmap.php
Did any South American Climbers feel this? Got to be some news here.
8.8 earthquak in Chile, news says 500 time more severe than the Hati quake.

PostPosted: Sat Feb 27, 2010 5:34 pm
by Day Hiker
8.8! :shock: :shock: :shock:

PostPosted: Sat Feb 27, 2010 5:40 pm
by lowlands
I read about it this morning. The Richter scale is a logarithmic scale, so it's definitely quite a bit more powerful.

PostPosted: Sun Feb 28, 2010 2:15 am
by phydeux
There was a tidal surge here on the Orange County (Southern California) coast about noontime, looking like a typical extreme tidal event but in a really compressed timeframe (extreme tides happen a few times a year). The waterline went out about 30 ft (horizontally), which would be about a 3 foot drop, and looked like an extreme low tide. It came back in about 1 hour later but only looked like a normal extra-high tide (maybe 3ft-6ft above mean tide level). No big surf. Very cool to watch while standing in the rain eating lunch on high ground. 8)

Supposidly the Coast Guard stopped entry/exit of big cargo ships into the big Los Angeles/Long Beach harbor complex this afternoon since the lowered water level would strand many of the ships on the bottom of both harbors' shipping channels. :shock:

PostPosted: Tue Mar 02, 2010 8:31 pm
by Genesis
awesome video. Had no idea it was like that and live just a few miles away.

PostPosted: Tue Mar 02, 2010 10:42 pm
by Diego Sahagún

PostPosted: Tue Mar 02, 2010 10:49 pm
by Diego Sahagún
TacoDelRio wrote:Kinda cool video my buddy linked to: http://www.youtube.com/watch?v=Imfd2tTpxv4

Nothing dramatic, but it's interesting.

The effect in Japan: http://www.youtube.com/watch?v=0RsFoik5z-8

And New Zealand: http://www.youtube.com/watch?v=1zG_ARyrEKM :shock:

PostPosted: Tue Mar 02, 2010 10:57 pm
by Diego Sahagún
Nothing compared with Thailand's 2004 tsunami:

http://www.youtube.com/watch?v=yBQzQGcK ... re=related

I'm not sure that's in 2006 but is impressive as well (English comments):

http://www.youtube.com/watch?v=l_a4N1ga ... re=related

:shock:

PostPosted: Tue Mar 02, 2010 11:11 pm
by Diego Sahagún

PostPosted: Wed Mar 03, 2010 9:01 pm
by RayMondo
Well, according to NASA JPL, the magnitude of the Chilean quake has caused the Earth's Axis to shift, and the Earth's rotation to speed up. Both, albeit by a small amount. It has occurred with other quakes, though I've not heard if this affects the GPS, especially as the length of day has now changed and that GPS clocks are corrected for Relativity.

<a href=http://news.nationalgeographic.com/news/2010/03/100302-chile-earthquake-earth-axis-shortened-day/>National Geographic</a>

<a href=http://http://latimesblogs.latimes.com/lanow/2010/03/chilean-quake-shortened-the-day-by-126-microseconds-jpl-scientists-says.html>Shortened day: LA Times</a>

The principle behind the increased speed of rotation is the "conservation of momentum". Because one of the tectonic plates has subducted, this equates to an ice skater drawing in their arms as they spin. The diameter being smaller, the energy has to go somewhere - hence increased speed.

Perhaps of more concern ought to be the subduction zone off the USA's NW coast. "Cascadia". This type of fault gives rise to Megathrust quakes (sudden uplifting). The potential here is that the zip zone is thousands of miles long, and travelling at a speed of 10,000km/h, would take 5 minutes to unzip. Hence the potential for a high magnitude, long duration event. 5 historical quakes have been observed in the geological record, averaging 300 yr intervals. The last in the 1700s. Such an event would also give rise to a large Tsunami.

We also get quakes in the UK. I have experienced one myself.

PostPosted: Thu Mar 04, 2010 9:55 am
by Day Hiker
RayMondo wrote:. . . GPS clocks are corrected for Relativity.


This is really fascinating stuff for anyone interested in Einstein's relativity theories, especially regarding their application in something encountered in everyday life.

Because an observer on the ground sees the satellites in motion relative to them, Special Relativity predicts that we should see their clocks ticking more slowly. . . . Special Relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 microseconds per day because of the slower ticking rate due to the time dilation effect of their relative motion.

Further, the satellites are in orbits high above the Earth, where the curvature of spacetime [ :shock: :shock: :shock: ] due to the Earth's mass is less than it is at the Earth's surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away. . . . As such, when viewed from the surface of the Earth, the clocks on the satellites appear to be ticking faster than identical clocks on the ground. A calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.

The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day ( 45-7=38 )!

From: http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html

PostPosted: Thu Mar 04, 2010 3:48 pm
by Snowslogger
TacoDelRio wrote:Kinda cool video my buddy linked to: http://www.youtube.com/watch?v=Imfd2tTpxv4

Nothing dramatic, but it's interesting.


Go onto a dock to film a tsunami :shock: Good thing it wasn't a big one.

old news now I suppose

PostPosted: Sun Mar 21, 2010 3:29 am
by Norman
http://www.alpinist.com/doc/web10w/news ... earthquake
Just ran into this, interesting event, worth reading.