The geology/Ham/electrical geeks will like this.

I was reading an article about the recent earthquake in Turkey and that about an hour before it happened, propagation on the 40M band was severely disrupted. I had to know more about about this and came across this webpage describing how/why this occurs.

An excerpt from the page:

It would take a major earthquake and a serendipitous observation by a scientist with a uniquely prepared mind to change the earthquake detection paradigm. After the catastrophic Tohoku earthquake, the magnitude 9.1 event that crippled the Fukushima-Daichi nuclear plant, caused a devastating tsunami, and claimed nearly 16,000 lives in March of 2011, most scientists were poring over seismographic data to learn more about the quake. But Professor Kosuke Heki of Hokkaido University in Japan had another thought: what if there had been changes to the ionosphere as a result of the earthquake?

Heki is an expert in space geodesy, the exploration of the Earth’s shape, position in space, and gravitational field using mainly space-based systems. He knew that changes in the ionosphere can affect GPS and GNSS receivers on the ground, and with Japan’s vast network of receivers to keep track of the smallest of movements of the Earth’s crust, he was able to spot an anomalous buildup of electrons directly above the epicenter of the quake. What’s more, the buildup preceded the start of the quake by 40 minutes.

On the face of it, it seems a bit far-fetched that the ionosphere could somehow react to what’s happening deep within the Earth. But there turn out to be deep electrical connections between the Earth and the atmosphere. The key to understanding these connections is in the microfractures that occur in rock at faults that are about to rupture. The strain that builds up in rock at a geological fault is not released in a single event. Think of breaking a pencil by slowly bending it – the pencil bends at first, the paint starts to crack, you hear a faint crackling as wood fibers begin to burst, and then the pencil suddenly pops in two. Rock behaves very much the same way, if on a much different scale, and it’s the microfractures that occur before the main fracture that can power ionospheric disturbance.

The theory goes that chemical bonds in the mineral grains of the rock, specifically the peroxy bonds that occur between two oxygen atoms, are broken by microfractures. This leaves a charge imbalance, with one side of the peroxy bond with an excess of electrons, and the other side with a positive hole. These holes tend to migrate from high stress to unstressed areas of the rock, which leads them to eventually reach the surface, leaving it with a net positive charge. As stress in the rock below increases, the number of positive holes reaching the surface rapidly multiplies, drawing electrons from the atmosphere to balance the charge. The moving charges generate an enormous electromagnetic field that can reach all the way up to the ionosphere, creating just the kind of anomalies that Professor Heki observed.

And, not to make this political, but this just reinforces what we all know, and that is that Mother Nature is so much more powerful than us tiny little parasites. The notion that we could have any effect on nature is simply laughable.

I bet it rattles VLF too.

That's very interesting finding. I guess the rest of the world does not have the sensor density to see this change in the ionosphere.

Thanks for posting that.

RMD