Regional Seismicity Patterns

These movies show maps of earthquakes through time, so we can compare regional patterns of seismicity at different plate boundaries. First, the Key shows how we represent magnitude and depth using the dot size, color and the sound.

In the continental US, the San Andreas Fault in California is the most seismically active. Here is 7 years of earthquakes between San Francisco and Los Angeles. You can see the San Andreas fault emerge as the movie plays. There’s a background rate.. that grinding sound representing the many small earthquakes, and then two big ones, M6.6 San Simeon earthquake in 2003 and then the M6.0 Parkfield earthquake a year later. You can hear the aftershocks. Those two big ones were felt in both San Francisco and LA, but the vast majority of these are only felt very locally.

Now we are going to look at a larger area in Southeast Asia, covering Thailand and Sumatra, part of Indonesia. There is so much more seismigicity here than in California— many of the smaller earthquakes you see are the size of the two large ones in California movie. The 2004 “Boxing Day” Great Earthquake was enormously destructive because of the tsunami. The rupture— the crack— that moved along the fault to produce the earthquake moved THE LENGTH OF CALIFORNIA IN ABOUT TEN MINUTES !

Tohoku, Japan:


Chile coming soon!

Do they talk to each other?

Human Induced Earthquakes !