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Earthquake Warnings in California

California is known for its earthquakes because it sits along what is known as the Ring of Fire in the Pacific basin. When residents are warned of an impending disaster ahead of time, they are naturally better able to handle the circumstances. Warning systems save lives and help people know when to expect a disaster so they can take the appropriate actions.

Setup
- The only way a warning system can work is to determine when the greatest risk of an earthquake exists. Because there is always a risk of earthquakes along a fault line, scientists need to figure out when there is a higher likelihood of seismic activity. To do this, they place sensors four to six feet deep in the ground along fault lines. These sensors are designed to detect even the slightest movement in the plates, which often signifies a coming earthquake.
Earthquake Waves
- When the plates move, different kinds of waves are emitted through the ground. The most powerful waves are the ones that most people feel and that cause all of the damage. As the plates begin to move along the fault line, however, smaller waves known as P waves are the first to reach the surface. These waves are weaker, but move much faster. The sensors detect those P waves and alert scientists that an earthquake is on the way. These waves provide one second of preparation time for every five miles from the earthquake source. But there is no way to differentiate between false positives from surface vibrations or determine the strength of the coming earthquake.
Cost
- One of the concerns with implementing an earthquake warning system to California is the cost. Sensors must be purchased and installed, and monitoring equipment is also needed. The federal government has provided funds to the state to begin implementation of the program, but it is not nearly enough. As of May 2011, cost estimates to fully implement an earthquake warning system for California alone are about $80 million. Extending that system to the other coastal states would add an additional $50 million.
Effectiveness
- Because of the short amount of time that the warning gives, the effectiveness of the system has been questioned. An earthquake warning system would give enough time to slow down mass transit vehicles and help heavy equipment operators take precautions. And the warning system might offer enough time to help residents take cover and protect themselves from the earthquake. While there would not be enough time to fully evacuate, there would be enough time to save lives and prevent some injuries. Residents must understand, though, that false positives are possible because of vibrations from the surface world, such as a large truck driving over a nearby road. In addition, the warning may signal a smaller, insignificant earthquake rather than a large one.

Nature