Those California Earthquakes disrupted HF radio....

[Tom.G]

...and so did the Canadian and Indonesion quakes.

An Amatuer Radio (Ham) operator runs what he calls an "RF Seismograph" in Vancouver, British Columbia that noted a blackout on 10 meter and above bands and increased noise on 80 meters. Here is the ARRL article with a few more embedded links.
http://www.arrl.org/news/report-california-earthquakes-disrupted-hf-propagation-on-west-coast

 

[Baluncore]

HF propagation is known to have a daily cycle, yet the article gives only a 24 hour record, without showing the normal daily variation expected, or a comparison with the day before or after. Most experienced radio amateurs would expect that type of change in HF propagation on a summer afternoon.

There is a worldwide array of vertical ionospheric HF sounders, downward looking sounders, and a whole array of SuperDARN sites. Surely that data set would hold sufficient evidence to demonstrate a statistical correlation between ionospheric conditions and earthquakes, if it was present. Anecdotal stories do not increase the available data, they confuse it.

Obviously I am sceptical. Maybe my training as a geologist, or my experience running an ITU HF monitoring station has blinded me. To make it a science, some realistic mechanism needs to be hypothesised and tested. What might that mechanism be?

 

[anorlunda]

The article says that the HF disturbance lasted 24 hours. That makes it even harder to imagine a mechanism.

 

[russ_watters]

Yeah, this seems iffy to me too.

 

[berkeman]

Obviously I am sceptical. Maybe my training as a geologist, or my experience running an ITU HF monitoring station has blinded me. To make it a science, some realistic mechanism needs to be hypothesised and tested. What might that mechanism be?

Maybe all the SoCal HAMs jumped on the air at the same time, and were stepping on each other.

 

[anorlunda]

Maybe all the SoCal HAMs jumped on the air at the same time, and were stepping on each other.

Well, what do you expect when Californians are involved?

 

[russ_watters]

Maybe all the SoCal HAMs jumped on the air at the same time, and were stepping on each other.

I was wondering how ten thousand radio transmitters perform while bouncing up and down and/or falling onto the floor. Clean signal?

 

[Baluncore]

There are the obvious sea tides, there are also Earth crust tides that we do not notice unless we use GPS or VLBI. There are tides in the atmosphere and also tidal variations in the ionosphere. I would expect an earthquake to be triggered by some event, I would expect that to include tidal forces. We might therefore expect the properties of the ionosphere to be very slightly correlated with earthquakes.

And I was wondering how much of the tidal energy went into disturbing the ground compared to an earthquake. The tidal energy would be distributed while the earthquake would be local.

So what electro/chemical/magnetic changes do we see near earthquakes? Does lightning strike more often near earthquakes? Do more people get asthma? Do more amateurs press the transmit button?

 

[russ_watters]

I would expect an earthquake to be triggered by some event, I would expect that to include tidal forces.

Can you explain why you think that?

 

[Tom.G]

Apparently there is some correlation. (looks more like a monograph than refereed)

Induced Earthquakes Ch. 7, "Tidal Triggering of Earthquakes"
https://link.springer.com/chapter/10.1007/978-94-015-9452-3_7

 

[Baluncore]

Can you explain why you think that?

Because the cyclic tidal stress is added to the accumulating crustal stress. If the accumulating stress increases slowly each day, then the failure point will first be reached when the cycle of tidal stress approaches a maximum.

 

[anorlunda]

Can you explain why you think that?

I think of dead trees as an analogy. When does a dead tree fall? It is more likely when the wind blows. As the strength of tree approaches zero, any perturbation can trigger the fall.

 

[russ_watters]

Sorry, I think I may have misread and misquoted, so let me try again:

There are the obvious sea tides, there are also Earth crust tides that we do not notice unless we use GPS or VLBI. There are tides in the atmosphere and also tidal variations in the ionosphere. I would expect an earthquake to be triggered by some event, I would expect that to include tidal forces. We might therefore expect the properties of the ionosphere to be very slightly correlated with earthquakes.

I do see how there should be correlation - and causation - between tides and earthquakes. Since tides also act on the atmosphere/ionosphere, the correlation would naturally connect earthquakes and radio -- but not the causation.

If I understand correctly now, then I agree.

 

[Baluncore]

If I understand correctly now, then I agree.

For sooth.
https://en.wikipedia.org/wiki/Correlation_does_not_imply_causation

 

[rbelli1]

When does a dead tree fall?

And your smoke detector battery fail.

BoB