My mother believed in earthquake weather. She also said that an earthquake could only happen on bright, clear days.
However....
"In the 4th Century B.C., Aristotle proposed that earthquakes were caused by winds trapped in subterranean caves. Small tremors were thought to have been caused by air pushing on the cavern roofs, and large ones by the air breaking the surface. This theory lead to a belief in earthquake weather, that because a large amount of air was trapped underground, the weather would be hot and calm before an earthquake. A later theory stated that earthquakes occurred in calm, cloudy conditions, and were usually preceded by strong winds, fireballs, and meteors.
There is no such thing as "earthquake weather". Statistically, there is approximately an equal distribution of earthquakes in cold weather, hot weather, rainy weather, etc. Very large low-pressure changes associated with major storm systems (typhoons, hurricanes, etc) are known to trigger episodes of fault slip (slow earthquakes) in the Earth’s crust and may also play a role in triggering some damaging earthquakes. However, the numbers are small and are not statistically significant."
- Dr. Malcolm Johnston USGS
We live atop a thin crust of shattered rock that's floating on a turbulent sea of magma (like a cork in a pan of water). These pieces of shattered rock are called tectonic plates. Picture a pot of macaroni boiling on your stove. Each piece of macaroni represents one tectonic plate. As the macaroni cooks, it's constantly churned around by the boiling water. So it is with the earth. While the macaroni has room to churn about, the earth's crust doesn't. The plates are packed together so tightly that it can’t move as freely as the macaroni can. It’s still being pulled and stretched by the “boiling” magma below, but since it can’t move freely, it builds up great pressure. When this pressure builds up enough force, it moves suddenly and we have an earthquake. The amount of pressure released equates the magnitude of the quake. While quakes occur daily, we generally only feel ones that register 3.4 or higher. Most earthquakes happen near where these plates meet.
So why does it seem that we’re having so many earthquakes lately?
Earthquakes have been happening since the world began. Lately, however, we have better ways of recording them. We have seismometers that can detect movement of the crust worldwide. It’s possible that there aren’t more earthquakes, but rather we’re able to “see” more of them.
It’s also possible that the melting ice caps are releasing downward pressure on the magma sea. A cork in a pan of water displaces a certain amount of water. If you push down on the cork, it displaces more water. Let go of the cork and it displaces less water. The earth’s crust is like that cork. When the ice melts the crust (cork) rises. This rise sends out ripples throughout the entire magma sea. The crust wants to ride these ripples (like a surfer) but since it’s packed so tightly, it can’t. Thus, more pressure builds. More pressure means more earthquakes – and stronger earthquakes.
It is also possible that our “heavy” cities are also displacing magma (the average skyscraper weighs 222,000 tons). The more buildings there are the heavier the city becomes. The heavier the city, the more the crust sinks in that area. That displaced magma pushes up elsewhere (pressure).
Shuhak 