What happens before a major earthquake?

Question

I refuse to believe there's no warning signs!

Off the coast of British Columbia, there have been a number of earthquakes over the last two days. Starting on August 27th, there has been 30 small earthquakes in the same general area. Most average around 4 on the richter scale but the largest has been a 6.1. Would this relieve tension before a major earthquake, or could it possibly be leading up to a larger one?

Answer 1

There are different theories out there regarding stress-buildup and earthquakes, and all of these have their own ideas of how warning signs could possibly be detected. One of the most prevalent theories is called the elastic rebound theory, which basically states that pressure slowly accumulates across the fault until it exceeds the shear strength of the locked-up bedrock, resulting in an earthquake. The theory then hypothesizes that the stress in the vicinity where the earthquake occurred has been relieved, and an earthquake won't happen there again until stress builds up again to the rock breaking point. There's a lot of evidence that supports this theory, and if it were true, then we would expect to be able to predict earthquakes simply based on time intervals from the last earthquake. The Parkfield, California project is a good real-life example that seems to support this theory.

The problem is that according to this theory, a swarm of small quakes should relieve the built-up stress, thus diminishing the likelihood of a sudden large earthquake. However, there have been some recent seismic occurrences like the swarm of microearthquakes beneath Reno, Nevada that have defied this logic. The quakes seemed to increase in magnitude with each occurrence instead of decrease.

Events like the Reno swarm of microseismicity give ammunition to the small group of professionals who believe that small quakes always precede larger ones, and that if we could install sensitive enough devices to detect the microseismicity, then we could predict earthquakes. The problem with this theory is that there has been no consistent pattern or evidence to prove that it's true. Sometimes it works, sometimes it doesn't.

So, in summary to answer your question, it varies what happens before a major earthquake. Sometimes you get foreshocks. Sometimes you don't. Sometimes animals get jittery, sometimes they don't. Sometimes Grandpa's sixth sense kicks in, sometimes it doesn't. In my opinion, humanity won't accurately be able to predict earthquakes with any regularity until it develops the technology to actually measure stresses within the rock deep beneath the ground surface. Such technology does not exist today, and it likely won't exist for at least several more decades, if ever.

Answer 2

Some man, roughly age of 62 in Boca Raton florida gets a bad shake in his knee...