[HN Gopher] M8.2 earthquake near Perryville, Alaska
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M8.2 earthquake near Perryville, Alaska
Author : wferrell
Score : 123 points
Date : 2021-07-29 07:29 UTC (15 hours ago)
(HTM) web link (earthquake.usgs.gov)
(TXT) w3m dump (earthquake.usgs.gov)
| [deleted]
| pmdulaney wrote:
| If you were speaking of a solar power installation you would say,
| for example, a 300 MW installation -- honoring Watt.
|
| Why, then, a M8.2 earthquake? Why not a 8.2 R earthquake to honor
| Richter?
| spchampion2 wrote:
| Because the magnitude is no longer defined using the original
| Richter scale. Earthquake magnitudes are now defined using a
| similar scale called the moment magnitude scale.
|
| Also watts are an SI unit of power, whereas Richters are not a
| unit of earthquake. It's just the name for the scale itself.
|
| https://en.wikipedia.org/wiki/Seismic_magnitude_scales
| pmdulaney wrote:
| Wow. I wonder if any local news station has ever said, "That
| earthquake with an epicenter in Whittier was a 4.5 on the
| moment magnitude scale."
|
| Thank you.
| olyjohn wrote:
| Don't they usually say "It was a magnitude 4.5 quake?"
| ineedasername wrote:
| Speaking of Watts, is there any way to translate the magnitude
| M for an earthquake into an equivalent MW of energy?
| dragonwriter wrote:
| > Speaking of Watts, is there any way to translate the
| magnitude M for an earthquake into an equivalent MW of
| energy?
|
| No, because while if other parameters are the same moment
| magnitude is logarithmic in energy, the other parameters
| differ between real earthquakes.
| robin_reala wrote:
| First worry is always a tsunami, but in this case it seems like
| it only generated a max of ~20cm:
| https://www.tsunami.gov/events/PAAQ/2021/07/29/qwzteb/7/WEAK...
| k_sze wrote:
| However, I wonder if this quake so up north would accelerate
| the breaking of icebergs.
| Turing_Machine wrote:
| There's no sea ice that far south at this time of year.
| Alaska is huge, yo.
| FunnyLookinHat wrote:
| We got an alert in Jefferson county letting us know
| specifically that there was no Tsunami.
| temp0826 wrote:
| Could have made the olympic surfing competitions interesting
| (which they moved sooner because of the storm that passed by)
| bamboozled wrote:
| The Tsunami was in Alaska, not Japan.
| akg_67 wrote:
| In Japan, TV advisory was extra rough seas (no tsunami) on
| pacific side throughout the day tomorrow (Friday) as a
| result of this earthquake.
| aaomidi wrote:
| You see, they're all connected to the same body of water.
| And if the tsunami was directional towards the Japanese
| coast it would've caused issues there.
| ceejayoz wrote:
| Here's the big Japanese tsunami that devastated Fukushima
| arriving in California.
|
| https://www.youtube.com/watch?v=jdMDCLwblkY
| vajrabum wrote:
| I only know this because I clicked on some more stuff
| after looking at that but the Fukushima tsunami caused a
| fair amount of damage in the Santa Cruz, CA harbor both
| to docks and boats. Apparently the waves can get
| magnified when they go into a narrow channel or harbor.
| Another thing I only learned today reading the comments
| of that video is that tsunami literally means harbor wave
| in Japanese.
|
| https://www.youtube.com/watch?v=_dC_tf4mhO4
| Turing_Machine wrote:
| Tsunamis from the 1964 Alaska earthquake (M9.2) killed 12
| people in California and caused damage in Japan and Hawaii.
| Tsunamis can travel for a very long distance in open ocean.
|
| Alaska is pretty close to Asia, especially if you look at
| the great circle distance.
|
| Cargo planes from China, Korea, and Japan normally refuel
| in Anchorage, and before the extended range of modern
| passenger jets, most passenger planes also had a refueling
| stop there.
|
| In 1983, KAL Flight 007, a Boeing 747 passenger airliner en
| route from New York to Seoul, was shot down by the Soviet
| Union after departing Anchorage and inadvertently entering
| Soviet airspace.
| sandworm101 wrote:
| There is old joke that if you use metric when announcing a 50mm
| tsunami, half of Americans will run for the hills. "~20cm"
| could mean half a foot or 20 _hundred_ meters depending on how
| much you remember from highschool. Many agencies have policies
| on how and where metric should be used in public announcements.
| gok wrote:
| Eh we know what a 9mm bullet looks like
| daneel_w wrote:
| Yes, but how many of you _reflect_ over the nomenclature?
| How many of you know the actual diameter of a "twenty-two"
| (even if spelled out as .22)? People don't often think
| about the meaning behind colloquialisms.
| dogorman wrote:
| American public schools have been using metric for
| decades. Science classes in American public schools use
| metric exclusively since the 80s at least. When you meet
| an American who makes a big deal out of not knowing what
| a meter is, 9 times out of 10 they're putting on a
| performative patriotic display mean to get a rise out of
| you. That, or they're quite elderly.
|
| Incidentally, .22 LR is _nominally but not actually_ 0.22
| inches in diameter. It 's very slightly bigger than that.
| In the domain of ammunition, there is often a mismatch
| between actual diameter and nominal diameter.
| sandworm101 wrote:
| With calibers there is a difference between american .22
| and european .22. As I understand it, the american
| measurement is slightly larger as it includes a bit of
| the rifling groves whereas the European standard was only
| the bullet width. So the same bullet measures slightly
| larger on the american scale. Or I might have that
| backwards, one of the two is different.
|
| https://www.rifleshootermag.com/editorial/comparing-
| american...
| dogorman wrote:
| From what I understand, ".22 LR" is nominally .22 inches,
| actually is .223 inches, and is labeled as 5.6x15mmR in
| Europe while actually being something like 5.66mm (the
| 'x15' is the length of the case in millimeters, and the R
| means rimmed.) They are called different things and both
| are not quite their nominal sizes, but I _think_ they 're
| interchangeable in practice.
| Scoundreller wrote:
| Or 10mm if you've wrenched a car
| abakker wrote:
| People know what the bolt looks like, but the wrench is
| missing.
| heisenbugtastic wrote:
| ahh fellow knuckle buster too
| [deleted]
| Koshkin wrote:
| It looks like .38SP!
| throwaheyy wrote:
| Americans use metric units to measure the size of guns and
| drug hauls, I think they have at least a minimal
| understanding of the magnitude...
| spywaregorilla wrote:
| fwiw pretty much all unfamiliar americans will associate
| 'centi' with small, not "hundred"(eth)
| cossatot wrote:
| The slip patch (where the two tectonic plates slip past each
| other) of the earthquake did not reach the sea floor, so it
| didn't generate a big tsunami [0]. If the purple colors in the
| finite fault map (indicating >2 m slip) reached the trench (the
| top of the first figure, or the red line in the second), then
| the earthquake would have displaced much more seawater.
|
| These finite fault maps are made using automated processing of
| the seismic waves from seismographs around the globe. It's
| pretty amazing to me that the resolution is so good, from what
| are not that different than sound waves. These tend to be
| pretty accurate, not just precise, and are validated from
| additional studies using different datasets over the subsequent
| years.
|
| [0]:
| https://earthquake.usgs.gov/earthquakes/eventpage/us6000f02w...
| flareback wrote:
| That's what I was wondering, thanks for the info.
| [deleted]
| ineedasername wrote:
| _the two previous large earthquakes in July and October 2020,
| those previous events were foreshocks of the July 2021
| earthquake_
|
| A year apart and they're still considered part of the same event.
| A nice reminder that in geological time, a year is less than an
| eyeblink.
| swader999 wrote:
| Time so see what Dutchsinse, the earthquake maverick says about
| this. https://m.youtube.com/watch?v=hhfLTDA8I9g
| ineedasername wrote:
| Pretty interesting, especially when he shows the buoys on the
| east cost that registered the quake & the plate overlay to show
| why they felt the quake (because they were on the the other
| edge of the plate).
|
| Kind of amazing he he managed to put up a 1hr+ video so soon
| after the quake, ~1.5 hours or so.
|
| Also a bit confusing why the comment posting this video is (as
| of my comment) getting downvoted? Is this youtuber not
| considered credible on the topic?
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(page generated 2021-07-29 23:02 UTC)