Seismologists recommend that people not live directly above earthquake fault lines. These fault lines demarcate plate boundaries whose movements in the Earth’s crust are the major reasons for earthquakes. In the U.S., the Pacific Rim states have the highest risks of earthquakes, although quakes have occurred in just about all of the 50 states.
The Earth’s crust is like a multi-layer cake, where the frosting (the outermost layer) is responsible for seismic activity. This layer is composed of tectonic plates that tend to slide around, over and under each other. Such movements can trigger earthquakes. The crust has three types of plate boundaries:
- Spreading Zone: caused by molten rock and found in the mid-Atlantic ocean.
- Transform Fault: occurs when plates slide over one another, for example at the San Andreas Fault in California
- Subduction Zone: found along the US northwestern coast, the Wasatch Range in Utah and in southern Alaska, they are associated with volcanic mountain ranges
Movement within an individual plate can also trigger a temblor. This is due to deep stresses that create weak zones. This is how New Madrid, Missouri got hit in 1812, with damage extending to six neighboring states. In 1886, 60 souls perished in the great Charleston quake that hit a 120-mile radius.
Faults are sure predictors of earthquakes. There are three types:
- Normal Faults: young rock displace older rocks – Death Valley Fault (California), Sevier Fault (Utah) and the Conjugate Normal Fault (southern Utah)
- Reverse Thrust Faults: old rocks displacement younger ones – Lewis and Fold Thrusts (Montana)
- Strike-Slip Faults: side-by-side displacement of rocks – Las Vegas (Nevada), San Andreas Fault (California) and Coos Bay (Oregon)
You should note that 80 percent of all US earthquakes occur in Alaska and California.
If you know you live in a fault zone, we recommend you own a well-equipped four-wheel drive vehicle that you can count on to make a quick getaway. Think about adding extra lighting equipment, such as aftermarket projector LED headlights and a battery-operated searchlight, to pierce through the tremendous dust kicked up by an earthquake.
If you discover that you have purchased a home that lies on a fault line, you might consider relocating to a safer area of the country. You owe it to yourself and your family to research your next home location so that you don’t find yourself in a similar situation. Remember, no location is 100 percent safe from earthquakes, but you can put the odds in your favor by avoiding significant fault lines.