I have experienced plenty of earthquakes where one person felt it quite strongly and another living nearby didn't.
How easy it is to feel varies depending on what floor you're on, how well constructed your building is, what kind of ground you're standing on, etc, etc, etc.
Furthermore at that distance the earthquake should be a slow roller, which means that someone who is focused on something might not notice while another person in the same room could notice, realize how much motion there is, and freak out. I've been there as well - as the person watching a movie who ignored an earthquake that everyone outside of the movie was quite aware of.
So the fact that you live in Moscow and didn't feel it is not grounds to call BS on someone else claiming that they felt it.
That's just too smart of a point, I'm afraid I'm all smitten. Though a construction next door or a demolition few blocks down the road would've been a simpler explanation.
Yeah, that was a little glib. My point was, testimony is what it is; pointless to guess at their situation. Perfectly fair to do statistics on reports, if found in sufficient numbers.
How can a tsunami cross the Pacific in 10 hours? Isn't that as fast as an airliner? Of course I'm not questioning the maps, but isn't that shocking? How does it work?
It's not a shock wave, it's a shallow water wave (because the wavelength is much larger than the depth of the ocean). The speed depends on depth [v = sqrt(g*H)]; for typical deep Pacific (5000 m), that is ~220 m/s or 500 mph.
I don't think there are waves that move "as a single mass of water across the ocean." or through any other medium. http://en.wikipedia.org/wiki/Waves:
"The term wave is often intuitively understood as referring to a transport of spatial disturbances that are generally not accompanied by a motion of the medium occupying this space as a whole,"
For an analogy with (not quite an explanation, as the mechanisms are a bit different) a tsunami's speed, think of what happens when you pluck a guitar string. The back end of the string starts moving up before you even release the string. So, say you lift a string at, say 1cm/s for .1 of a second. (Almost) at the end of that 0.1s, the start of the wave that will form has reached the other end of the string, moving at meters per second (the 'almost' is because the string will deform. Ultimately, relativity has something to say here, too, but that only matters when the resulting wave signal would move near the speed of light)
However, I argue that the NOAA could serve their warnings on the web in all lowercase for the sake of readability. Then again, that could be a quick hack for someone.
NOAA / NWS advisories tend to have a lot of proper names. It looks really wacky if you just lower-case them (and it's non-trivial to convert them to proper capitalization automatically.)
(I tried to do this back in about 1999. I don't think it's gotten much easier, although having geo APIs might help somewhat.)
Quick hack, maybe. But someone getting the time to do so is another issue. And these are old systems, you want them to do the work so you can read a tsunami warning that happens how often?
It's more readable in all caps, which is why they and the military do it this way. If it were all lowercase thing like Is and ls and 1s would get confused.
Especially for submarines, to communicate underwater you need very low frequency radio and the bandwidth is correspondingly low. Sure they can surface and get satellite signals but that's not always practical depending on where they are and what their mission is.
You might be interested to know that Naval message traffic is now permitted to use lowercase letters in some instances (think shore-side). This is an extremely recent change but I think I've even seen it used already with a message released from SECNAV.
fwiw the tsunami warning systems (one each coast) in the usa are currently in the process of selecting and implementing a major upgrade (i am working on one of the bids in a very minor role[1]) so you can expect changes in the next few years (but i have no idea about this particular issue).
[1] which, incidentally, involved me sending thousands of SMS alerts to a co-worker yesterday evening as i ran through a replay of the chile earthquake, effectively DOSing[2] his phone. most entertainment i've had in months. beep. new magnitude estimate. beep. beep. beeeeep... :o)
We felt a small earthquake in Davis, CA earlier tonight. Active day for our earth! I quite like earthly events like this — they really make one realize how minuscule we are.
I was in mountain view for the '89 loma prieta quake. The walls of our tilt-up on easy street we're waving like flags, and the huge Costco shelves in the shipping room collapsed, shattering a workers arm. I know that this is nothing like the horrors that other people in quakes have faced, but for years afterwards my flesh would crawl when a large truck would pass by. Then I moved to Oakland just in time for the '91 firestorm...
I imagine NOAA and NWS bulletins are in all caps for compatibility with ancient systems, but I still have to wonder if they'll ever see a reason to start using lowercase letters.
it's just past midnight here in socal. I live in Long Beach, CA - few miles from the pacific ocean. I'm closely watching http://ptwc.weather.gov/ . No warning as of this writing.
Is it crazy to think that there may be a pattern for all these strong earthquakes in the past few years since the Haiti one, and that they may be linked?
It's the Pacific Ring of Fire, which includes Haiti, Japan, Chile, New Zealand, Solomon Islands and Indonesia (list goes on) which have had deadly quakes in the last few years - http://en.wikipedia.org/wiki/Ring_of_Fire
*edit, not Haiti which has its own crazy deep-earth stuff going on in the area
I personally always get Haiti and Papua New Guinea confused in my head. I know they are very different, but for some reason I have to think for a few seconds when someone says Haiti.
Is that it? I think its just a neural hash collision in my head that resulted from hearing about missions in both countries in catholic elementary school (they are both very poor, at least PNG and Haiti).
I have read speculation about that too. I don't think it's crazy, but I don't think it's widely accepted as a significant correlation by seismologists either.
indeed, as this document indicates :
"DUE TO THE DEPTH OF THE EARTHQUAKE NO TSUNAMI IS EXPECTED."
The Depth of the subterranean earthquake is generally a major factor in Tsunami (The main factor being the displacement of the water mass above).
The last two M9~ magnitude earthquakes causing deadly tsunamis (Indian Ocean 2004, Japan 2011) were only at a Depth of 30km (19mi). This one is very deep, at 619km (385mi) below the surface.
