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8.9 earthquake hits Japan

earthquake.usgs.gov

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Re: 8.9 earthquake hits Japan

#241

Post by donw »

melvinram wrote: post #123

Red Cross and others will likely be jumping to the aide of those who have been affected by this disaster. If you have a website, please consider adding a message and link to the Red Cross donation website or the link to the donation page of any other website. To get it up ASAP, I've used the HelloBar ( http://www.hellobar.com ) on my site. You can see a working version of it at http://www.webdesigncompany.net but rea…

I set up a WePay donation page, but this is way better if you've got any sort of traffic. Let's help these people out.

Re: 8.9 earthquake hits Japan

#242

Post by Cafesolo »

eru wrote: post #129
patio11 wrote: post #101

Earlier quoted context omitted.

It's because everyone in Japan started sending SMSes to everyone they knew practically before the shaking stopped and that DOSed the network. This happens fairly regularly (e.g. for a few minutes after midnight on New Years, when a large portion of Japanese people send well wishes within the same 15 second window).

From my experiences in Germany, SMSes send around midnight New Year did sometimes take several hours to arrive.

Same in Argentina.

Re: 8.9 earthquake hits Japan

#244

Post by JoachimSchipper »

wtallis wrote: post #232
epochwolf wrote: post #194

Earlier quoted context omitted.

The doesn't work very well when each device requires a separate communication channel like a cell phone.

It should be much easier for cell phones, since the underlying physical medium is a broadcast medium. It takes significant engineering effort to get rid of this capability.

That would require a completely separate, unencrypted broadcast protocol. Yes, you could design that, but who will pay for it?

Re: 8.9 earthquake hits Japan

#245

Post by petercooper »

jarin wrote: post #228
petercooper wrote: post #225

Earlier quoted context omitted.

What's funny is that I was around just after the quake was reported and thought.. "Ooh, no-one's posted it to HN! I should post it." Then I thought "Nah, it's just world news. HN won't care directly about a quake." Then minutes later, this got submitted anyway.

I know, it's totally shocking that hackers care about something other than money or code.

Haha, but that's not exactly the point. I hesitated about posting the earthquake news much like I'd hesitate posting about, say, the discovery of a new planet. It would likely be of interest to hackers but it's not really in the gamut of Hacker News submissions.

Re: 8.9 earthquake hits Japan

#246

Post by angus77 »

TorKlingberg wrote: post #207
angus77 wrote: post #161

Earlier quoted context omitted.

It was on Japanese TV news almost immediately. We were watching it in the office while we were still shaking.

I bet the NHK has a special team always waiting to report on earthquakes and tsunami warnings. They report on many of the smaller quakes very quickly too.

Yeah, whenever there's a quake sizeable enough to feel it, just turn on the TV---they're on it before you even have time to tune it.

Re: 8.9 earthquake hits Japan

#247

Post by gurtwo »

veidr wrote: post #56

An interesting thing I noticed was that all cell phones were completely useless for a pretty long time following the quake. That's normal, but one difference this time, compared with several years ago, is that most people I know no longer have a landline phone at home. People were queuing up for like 20 minutes to use the one old green plastic coin-op pay phone accross the street. At first, I didn't think to use a ph…

I strongly suspect this is not due to an outage in the network, but rather intentional. Some years ago I worked on a project for a Japanese mobile operator to implement a system that prevents "normal" mobile phones from making calls to avoid overloading the network. When activated, only emergency services (fire fighters, police, medical, ...) are allowed to call. At regular intervals, a batch of the "civilian" phones are allowed too for a while, then a different batch, etc, so everyone gets its chance to call if they wait long enough.

The system was a government requirement for events such as yesterday's quake, but I can't confirm all phone disturbances reported were/are due to it.

Technically, it relies on a bitpattern called "accessClasssNBarred".

Re: 8.9 earthquake hits Japan

#248

Post by wisty »

jules wrote: post #222
mrcharles wrote: post #171

Earlier quoted context omitted.

From Wikipedia: The energy release of an earthquake, which closely correlates to its destructive power, scales with the 3⁄2 power of the shaking amplitude. Thus, a difference in magnitude of 1.0 is equivalent to a factor of 31.6 ( = (101.0)(3 / 2)) in the energy released; a difference in magnitude of 2.0 is equivalent to a factor of 1000 ( = (102.0)(3 / 2) ) in the energy released.[2]

How does energy scale with distance from epicenter?

Small earthquakes have a lot of energy in the higher end of the frequency scale, which is rapidly dissipated.

Larger earthquakes have more low-frequency energy, so they go further.

There's no simple equation, they just use regression to fit the attenuation as a factor of 1/r, 1/r^2 (...), and for magnitude, and for frequency.

You can start here: http://earthquake.usgs.gov/hazards/about/attenuation.php

Re: 8.9 earthquake hits Japan

#249

Post by wisty »

jules wrote: post #240
ars wrote: post #233

Earlier quoted context omitted.

Probably goes down by r^2 However earthquakes may be "flat", in which case it's by r (i.e. r^1). It's probably somewhere in between those.

Wouldn't it go down by r^2 if the earthquake is flat, and by r^3 if it's not?

No. A circle with 2X the radius has 2X the diameter, thus the energy will be cut in half.

Unless you also expect a linear attenuation, due to energy loss through the bedrock.

Re: 8.9 earthquake hits Japan

#250

Post by wisty »

phlux wrote: post #203
solipsist wrote: post #14

And there's already a growing Wikipedia article on the earthquake: http://en.wikipedia.org/wiki/2011_Sendai_earthquake

WTF - That article states 6,000,000 SIX MILLION deaths? Can this be accurate? It reiterated what I heard on the news regarding passenger trains missing due to the Tsunami - but 6MM??? EDIT: Looks like wiki-trolling... From CNN: The official death toll stood at 137, with 539 injured and 351 missing, according to Kyodo, citing police, but that death toll seemed almost certain to rise -- from 200 to 300 bodies have been…

Death toll from disasters is always low to start. Rescue workers on the ground are more worried about digging out the people who survived (at least for the first 48 hours or so).
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