
Tsunami warning issued after magnitude 7.9 quake hits east of Papua New Guinea - denzil_correa
http://www.reuters.com/article/us-papua-quake-idUSKBN1460CF
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hownottowrite
USGS runs a customizable earthquake notification service:
[https://sslearthquake.usgs.gov/ens/](https://sslearthquake.usgs.gov/ens/)

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themoat
They have a interactive map of latest earthquakes I've been looking at for a
few minutes now. I have never considered how many earthquakes (albeit mostly
minor) occur daily. There were 68 with magnitude of 2.5 or higher today!
Really fascinating to consider.

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foota
I was mostly joking last time I posted this (and as perhaps should have been,
was downvoted) but this is the third or fourth major earthquake on the pacific
rim in the last month or so. Couldn't these be signs of a very strong
earthquake to come?

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vtange
What scares me is how it's been mostly the western Pacific Rim (Japan, Taiwan,
Indonesia) getting quakes. That tells me that things might be getting a little
unstable on the eastern Pacific Rim, assuming the Earth keeps things
"balanced".

Chile did get a huge one a while ago, no?

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thesmallestcat
Well, an earthquake relives stress along a fault. It's not like there's some
feedback effect where the shocks before, during, and after a quake cause
further instability on the other side of the planet just because they share a
tectonic plate.

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YeGoblynQueenne
That was a massive earthquake and it's unbelievable luck that there are no
reports of casualties (probably because it hit a rural area).

But, please, can the title be corrected? The magnitude of the quake was 7.9 on
the (logarithmic) Richter scale. That's considerably different to 8.0 scale
(by a few million gigajoules at that).

Edit: Thanks for the correction. To give an idea of the difference in
magnitude:

    
    
      8.0 Richter in joules: 63,095,730,000,000,000.00
      7.9 Ricther in joules: 44,668,360,000,000,000.00
    

(According to:
[http://www.convertalot.com/earthquake_power__calculator.html](http://www.convertalot.com/earthquake_power__calculator.html))

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kevinbowman
From the wikipedia article [0]:

> In the United States, the Richter scale was succeeded in the 1970s by the
> moment magnitude scale. The moment magnitude scale is now the scale used by
> the United States Geological Survey to estimate magnitudes for all modern
> large earthquakes

which is similar but not the same. From that page's wikipedia article:

> Popular press reports of earthquake magnitude usually fail to distinguish
> between magnitude scales, and are often reported as "Richter magnitudes"
> when the reported magnitude is a moment magnitude (or a surface-wave or
> body-wave magnitude). Because the scales are intended to report the same
> results within their applicable conditions, the confusion is minor.

The difference mostly seems to be to do with distinguishing several quakes in
a similar location.

I know it's picky, but this _is_ HN...

[0]
[https://en.wikipedia.org/wiki/Richter_magnitude_scale](https://en.wikipedia.org/wiki/Richter_magnitude_scale)

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bhrgunatha
The factor changes for a 1 point increase are different.

Richter 10 (to the power 1)

Moment magnitude about 32 (to the power 1.5)

For an increase of 2:

Richter exactly 100

Moment magnitude exactly 1000

