Those California Earthquakes disrupted HF radio....

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Discussion Overview

The discussion revolves around the impact of recent earthquakes in California, Canada, and Indonesia on HF radio propagation. Participants explore the relationship between seismic activity and radio signal disturbances, examining both anecdotal evidence and scientific mechanisms.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants note that an "RF Seismograph" in Vancouver detected changes in HF bands during the earthquakes, suggesting a potential link between seismic events and radio propagation.
  • Others express skepticism about the claims, arguing that the article lacks a comprehensive analysis of normal daily variations in HF propagation and does not provide sufficient data to establish a correlation.
  • One participant questions the feasibility of a mechanism that could explain the observed disturbances lasting 24 hours.
  • Several participants humorously suggest that increased activity among amateur radio operators in Southern California could account for the disturbances, rather than seismic activity.
  • Some participants propose that tidal forces may play a role in triggering earthquakes, and they speculate about the potential correlation between tidal variations and ionospheric properties.
  • There is a discussion about the cyclic nature of tidal stress and its possible influence on the timing of earthquakes, with analogies drawn to natural phenomena like dead trees falling due to wind.
  • One participant references a chapter on tidal triggering of earthquakes, suggesting that there may be some correlation worth exploring further.
  • Another participant acknowledges the potential for correlation between tides and earthquakes, while distinguishing correlation from causation in the context of radio disturbances.

Areas of Agreement / Disagreement

Participants generally express skepticism about the claims linking earthquakes to HF radio disturbances, with multiple competing views on the mechanisms involved and the validity of the evidence presented. The discussion remains unresolved regarding the nature of the relationship between seismic activity and radio propagation.

Contextual Notes

Limitations include the lack of comprehensive data comparing normal HF propagation patterns and the absence of a clearly defined mechanism linking earthquakes to radio disturbances. Some participants also highlight the need for more rigorous scientific inquiry into the proposed correlations.

Tom.G
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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?
 
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The article says that the HF disturbance lasted 24 hours. That makes it even harder to imagine a mechanism.
 
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Yeah, this seems iffy to me too.
 
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Baluncore said:
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.

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

:smile:
Well, what do you expect when Californians are involved? :rolleyes:
 
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berkeman said:
Maybe all the SoCal HAMs jumped on the air at the same time, and were stepping on each other.

:smile:
I was wondering how ten thousand radio transmitters perform while bouncing up and down and/or falling onto the floor. Clean signal?
 
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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?
 
Baluncore said:
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?
 
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russ_watters said:
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.
 
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russ_watters said:
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.
 
  • #13
Sorry, I think I may have misread and misquoted, so let me try again:
Baluncore said:
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.
 
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  • #15
anorlunda said:
When does a dead tree fall?

And your smoke detector battery fail.

BoB
 
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