HFU HF Underground
General Category => General Radio Discussion => Topic started by: ChrisSmolinski on July 11, 2019, 1216 UTC
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British Columbia radio amateur Alex Schwarz, VE7DXW, said that an Independence Day magnitude 6.4 earthquake in California’s Mojave Desert and multiple aftershocks negatively affected HF propagation on the US west coast. Schwarz, who maintains the “RF Seismograph” and has drawn a correlation between earthquake activity and HF band conditions, said the radio disruption began at around 1600 UTC on July 4, and continued into July 5. He said that on July 4, the blackout was total except for 20 meters, where conditions were “severely attenuated,” Schwarz said. The RF Seismograph also detected the magnitude 7.1 earthquake on July 6 in the same vicinity, Schwarz reported. The distance between the monitoring station in Vancouver, British Columbia, and that quake’s epicenter is 1,240 miles.
Full story:
http://www.arrl.org/news/view/report-california-earthquakes-disrupted-hf-propagation-on-west-coast
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I'm interested to know more about the mechanism behind the noise. Schwarz refers twice to "field lines" from the quakes, but what generates them? Rock scraping on rock shouldn't, but perhaps the movement of ferromagnetic material in the plates through the Earth's magnetic field generates spurious electric fields and RF disruptions?
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https://en.wikipedia.org/wiki/Piezoelectricity
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https://news.stanford.edu/pr/91/911231Arc1006.html
There's also an ex-usgs guy who has made a career out west of predicting earthquakes using pet lost-and-found ads in the San Jose Murky News.
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I'll say that since the quakes, the HF bands haven't been exactly great anywhere. I noticed today, on a few different Kiwis, the static from lightning was nil, but the underlying hiss was S5 - S7 or more, with no evident QRM to cause it. It was just like a dull sizzle, not pops or buzzing.
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https://en.wikipedia.org/wiki/Piezoelectricity
Thanks for the link. I knew currents could deform slices of crystal to create buzzers, but was not aware this worked in reverse on a grand scale.
There's also an ex-usgs guy who has made a career out west of predicting earthquakes using pet lost-and-found ads in the San Jose Murky News.
I think I heard this guy on "Art Bell's Somewhere In Time" last weekend. The name escapes me, but the guest was talking about how animals start running away in larger numbers in the lead up to quakes. He mentioned something I'd never considered, as intuitive as it is: the longer a fault goes without a several smaller quakes, the larger the next quake will be.
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"Thanks for the link. I knew currents could deform slices of crystal to create buzzers, but was not aware this worked in reverse on a grand scale."
Just a musing, why wouldn't it work on a continental scale?
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I'd figure it's a process that only works on the surface of materials, and that surface area to volume for continental plates is much smaller than on small crystals. Some processes dont scale very well in chemistry or physics. And then I'd suspect that whatever RF is being generated is being severely attenuated by gigatons of earth between it and free space.
But now I know better!
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https://news.stanford.edu/pr/91/911231Arc1006.html
There's also an ex-usgs guy who has made a career out west of predicting earthquakes using pet lost-and-found ads in the San Jose Murky News.
I remember that guy. I understand he passed recently.
He was doing some groundbreaking work involving penguin behavior in south Chile before those big 8 mag. quakes there towards the end.