Okay, I’ve only seen the first two theories, but some people believe the world is flat–you never know. Today, there was an 8.1 magnitude earthquake offshore Chiapas, Mexico. While reading about the devastation of the quake, I noticed peculiar comments about its cause. There were suggestions the powerful quake was caused by the recent solar flare or cloud seeding.
Sorry to disappoint the conspiracy theorists, but the earthquake was caused by normal faulting. Click here to read the data on today’s Mexico quake and search your own area. You might be surprised by just how many earthquakes are occurring around the world at any given time.
A Brief Explanation of the Common Causes of Earthquakes
The Earth’s crust is a jigsaw puzzle of continental and oceanic plates. They move apart, push together, or slide past each other. In the study of plate tectonics, these processes are called plate divergences, plate convergences, and transform boundaries.
Large faults within the Earth’s crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as subduction zones or transform faults. (Subduction is simply a fancy word for crust plunging into the mantle.) Energy release associated with rapid movement on active faults is the cause of most earthquakes.
The most powerful earthquakes tend to fall on subduction zones. The 2011 Japan earthquake and tsunami is an example of this. The 9.0 earthquake was caused by the rupture of a stretch of the subduction zone associated with the Japan Trench, which separates the Eurasian Plate from the subducting Pacific Plate. (Some geologists argue that this portion of the Eurasian Plate is actually a fragment of the North American Plate called the Okhotsk microplate.) Read more on Britannica.com
On a personal note, this is one of the reasons those living in the Pacific Northwest often hear about “The Big One.” See the image below.
There are two kinds of plate divergences (moving apart):
- Divergent oceanic crust (such as the Mid-Atlantic)
- Divergent continental crust (as in the Rift Valley of East Africa)
There are three kinds of plate convergences (pushing together):
- Oceanic crust toward continental crust (west coast of South America)
- Oceanic crust toward oceanic crust (northern Pacific)
- Continental crust toward continental crust (Himalayan Mountains)
Transform boundaries mark the locations at which crustal plates move past one another (such as the San Andreas Fault)
To use an interactive plate tectonic map, click here to visit Geology.com
There are other types of earthquakes, such as volcanic quakes and those associated with hydraulic fracturing. Earthquakes and hydraulic fracturing is an issue close to my heart as I was born and raised in Oklahoma. Before moving to Oregon, I experienced several earthquakes there. I think that is an issue of its own and deserving of a separate post.
In short, most of the time earthquakes occur, it’s because the Earth is a living and breathing thing. Studies have found no correlation between solar flares and earthquakes and cloud seeding producing earthquakes is just a really out there theory.