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Shallow M5.1 quake from North Carolina changes 40 m propagation

Discussion in 'Ham Radio Discussions' started by VE7DXW, Aug 10, 2020.

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  1. VE7DXW

    VE7DXW Ham Member QRZ Page

    Hi Everybody;


    M5.1 4 km SE of Sparta North Carolina 2020-08-09 12:07 40 m atten., precursor (-1 h to +1 h)

    Today there were 14 significant earth quakes that were recorded by the USGS ranging in the size from M4.5 to M5.3.

    All of these quakes were recorded by the RF-Seismograph. For details and a graphical capture of the propagation and explanation see graph below.

    Synopsis: After all the clusters of local quakes just before the day changes 30 m comes up after the change of the day. It was open until 01:00 UTC and then there was a brief period of 20 m activity for 10 min. The first quake of the day was the M4.5 from Alaska that struck at 01:51 UTC and it attenuated all the bands, starting at 01:00 UTC for more than 3 h. The noise dropped again as a result of the M 4.9 from Indonesia and several local clusters of quakes that released around 06:00 UTC, which also created small 20 m noise spikes and raised the 15 m noise level. 40 m was available after 02:00 UTC, but noisy. As the 40 m noise level drops at 05:30 UTC, propagation continues and is enhanced by the M4.8 from India that struck at 08:50 UTC and the M4.9 from Iran that followed within 26 min. 80 m also was effected by these quakes and it opens after 09:00 UTC for 3 h until the M5.1 from North Carolina, that was felt and reported by almost 100.000 people ( acc. to USGS), because it was a very shallow quake. 40 m drops out at 10:45 UTC with the precursor of the M5.1 from North Carolina that struck at 12:07 UTC. It was followed by the M5.2 from Mid-Atlantic Ridge 35 min later, which created a post 40 m propagation opening. Interesting is the 40 m noise dome at 14:15 UTC and the 20 m, 15 m and 10 m noise increase. That was created by the transition between the two M5.2 quakes. The second M5.2 was from Alaska at 14:57 UTC and it completely changed the propagation and it raises the 80 m noise level after 15:00 UTC as well. Followed by the M5.3 from Prince Edwards Island that released at 16:30 UTC and the M 4.9 from China 43 min after, all bands stayed closed, except for the opening on 15 m that came in right after the M4.9. This can be attributed to a break in the ionosphere that lets solar wind though. The 15 m opening starts at 17:00 UTC and lasts for 90 min. As the shock-waves of these previous quakes rotate around the world the 20 m band starts to become sporadic after 19:00 UTC lasting for the rest of the day. The M4.6 from Central America that release at 20:40 UTC was followed by a local minor quake and three M4.5 that made propagation very sporadic for the rest of the day.


    Mag Location Time Depth [km] Detected

    M4.5 42 km S of Ozernovskiy Russia 2020-08-09 22:40 116.17 20 m atten.

    M4.5 43 km NNE of Wewak Papua N.G. 2020-08-09 22:36 10.0 20 m atten.

    M4.5 160 km S of Bambanglipuro Indon. 2020-08-09 22:12 10.0 20 m propag.

    M4.6 138 km W of Waingapu Indonesia 2020-08-09 21:31 35.0 20 m propag.

    M4.6 off the coast of Central America 2020-08-09 20:40 10.0 40 m noise incr., 30 m noise dome, 20 m atten.

    M4.9 234 km WSW of Qamdo China 2020-08-09 17:13 10.0 30 m noise spikes, post 15 m propag.

    M5.3 Prince Edward Islands region 2020-08-09 16:30 10.0 all bands atten., precursor (-1 h to +1 h)

    M5.2 120 km SE of Perryville Alaska 2020-08-09 14:57 32.6 80 m noise incr., 40 m atten., 20 m noise incr., precursor (-1 h to +1 h)

    M5.2 central Mid-Atlantic Ridge 2020-08-09 12:42 10.0 80 m atten., 40 m atten., precursor (-1 h to +1 h)

    M5.1 4 km SE of Sparta North Carolina 2020-08-09 12:07 3.7 40 m atten., precursor (-1 h to +1 h)

    M4.9 35 km SW of Sarpol-e Ziahab Iran 2020-08-09 09:16 10.0 80 m atten., 40 m propag.

    M4.8 242 km N of Along India 2020-08-09 08:50 10.0 80 m atten., 40 m propag.

    M4.9 137 km SSE of Dompu Indonesia 2020-08-09 04:52 10.0 noise decr. on all bands except 80 m

    M4.5 77 km SSW of Sand Point Alaska 2020-08-09 01:51 45.8 all bands atten., 80 m, 40 m noise incr., 30 m noise decr.

    If you want to receive these earthquakes reports on a regular bases please join the group. Please feel free to forward this message to third parties.

    All the best and 73;

    Alex - VE7DXW
  2. KN4CQB

    KN4CQB XML Subscriber QRZ Page

    I am in Charlotte, about 60 miles away. Never felt it though some friends did.
    VE7DXW likes this.
  3. KK4NSF

    KK4NSF Ham Member QRZ Page

    Interesting. I've read your posts, and the discussions surrounding it.

    I do a lot of raw data number crunching using an older Super's not as fast as some computers, but it does run numerical calculations quite nicely. Much of my work involves finding tiny trends / correlations that are apparently buried in noise. It would be interesting to take your raw data (I assume it's in CSV format) and run a time based algorithm on it and on available seismic data. That could possibly reveal a direct correlation, if one exists as hypothisized.
    VE7DXW likes this.
  4. VE7DXW

    VE7DXW Ham Member QRZ Page

    send me an e-mail:
  5. W4HWD

    W4HWD Premium Subscriber QRZ Page

    I’m 45 miles from the epicenter. Only way I knew it happened was seeing a report on the news. Felt nothing and I was out working in a manhole at the time.
    VE7DXW likes this.
  6. N6PAT

    N6PAT Platinum Subscriber Platinum Subscriber QRZ Page

    Is this a rehash of the Alaska Earthquake thread?
    WN1MB likes this.
  7. WA1GXC

    WA1GXC Ham Member QRZ Page

    Cheer up. It gets worse.
    WN1MB likes this.
  8. WX7P

    WX7P XML Subscriber QRZ Page

  9. AG6QR

    AG6QR Premium Subscriber QRZ Page

    The unusual thing about the M5.1 quake in NC was that it happened in a populated place that rarely experiences quakes large enough for people to feel. So lots of people felt it, and for many, it was their first time feeling an earthquake. That certainly made it newsworthy.

    But it wasn't an unusually strong quake, in the global scheme of things. There are around a thousand earthquakes of M5.0 or greater per year, which works out to around one every nine hours on average (with a lot of variability).

    In the original post we see an accounting of quakes down to M4.5. These occur more often, around every couple of hours. There were 14 such earthquakes on the day in question, which is not particularly high or low. There were propagation changes during that day, as well. The way I read the account, there were multiple propagation changes that day, sometimes the bands opened, and other times they closed. Sometimes the propagation changes happened before a quake, sometimes after. When you have 14 quakes happening at random times through the day, is it any surprise that events like propagation changes sometimes happen within an hour or so of quakes?

    Here's a list of M4.5 quakes that happened during the last day and week. The list and map is continuously updated. Next time you notice that the bands open or close (or notice your dog acting strangely, or notice unusual weather), check this website, and you may notice that an earthquake has happened within the past hour or so. If not, check in another hour or two -- you may have found a "precursor".
    VE7DXW and N0TZU like this.
  10. W4HWD

    W4HWD Premium Subscriber QRZ Page

    "The unusual thing about the M5.1 quake in NC was that it happened in a populated place that rarely experiences quakes large enough for people to feel."

    Not really.

    The epicenter was near Sparta, in Allegheny County, in northwestern NC. Allegheny County is a rural, sparsely populated county in a very sparsely populated corner of the state. Not as if it happened under Winston-Salem, or Hickory, the closest towns with significant populations, and both at least 50 miles distant. Charlotte is even further away (~90 miles as the wave travels).

    Must have been deep because as stated earlier, I was only 45 miles away (in Lenoir) and I only knew about it when I heard about it on the news.

    It did cause damage in the immediate area of the epicenter though.
    Last edited: Aug 11, 2020

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