Living in California guarantees three things: sunny weather, high costs of housing, and the common occurrence of earthquakes. While the magnitude of disaster depicted in movies like San Andreas can only be described as hyperbolic, ‘quakes’ are still a serious threat in many parts of the state. With the increasing danger of a Loma Prieta-style shaking happening in the next few decades, it’s important to understand this powerful natural process, and what to do when— not if— one hits.
The Science of Earthquakes
Earthquakes occur when two blocks of the earth slip past each other suddenly and violently. While the world’s tectonic plates are constantly shifting, the earth can become temporarily stuck at the boundary areas, or fault lines. This results in a massive buildup of energy that is spontaneously released when the force of movement overpowers the force of friction keeping the plates stable. When small “patches” of earth break loose around a fault line, smaller earthquakes happen. If these patches begin to cascade and “unzip” the length of the fault, the strength of the earthquake intensifies.
To learn more, we spoke to Steve Hickman, Director of the Earthquake Sciences Center at the United States Geological Survey (USGS). “We get a lot of magnitude 1’s and 2’s that people would never feel on the surface, and then occasionally we’ll get a magnitude 3 or 4 which will remind people that we live in earthquake territory. Every time the magnitude scale of an earthquake increases by one, the amount of energy that gets released goes up by a factor of thirty, and the number of earthquakes drops by approximately a factor of ten. In general the threshold for damage in Northern California is about a magnitude 5.”
For reference, disastrous earthquakes such as Loma Prieta in the Bay Area and Northridge in Los Angeles registered at 6.9 and 6.7 on the Richter scale, respectively. Combined, these events killed 120 people, injured over ten thousand and caused many billions of dollars of damage across California.
The USGS and its partner institutions estimate that there is a high level of probability that an earthquake of 6.7 or greater will occur in Northern California in the next 30 years. In the San Francisco Bay Area, the calculated probability of such an event is 72 percent over the next three decades. Although the San Andreas fault is more widely known, a major earthquake would more likely originate within the Hayward-Rodgers Creek fault system or the Calaveras fault, both in the East Bay.
Though an earthquake centered there would hit places like Oakland and Hayward the hardest, Hickman insisted that the Greater Bay Area would be affected by earthquakes on East Bay faults or the San Andreas. “People need to be prepared for either one. A big earthquake produces damaging ground motions, disrupt communications, produce fires, landslides, and liquefaction. It would be a huge economic disruption to the Bay Area. Casualties, if it were a big earthquake on the Hayward or the San Andreas in population centers, would be much higher than the Loma Prieta earthquake, as would be the economic losses.”
But Los Angeles is not off the hook either. The USGS estimates a 60 percent chance of a similarly large earthquake occurring in the same time frame. “It’s those bigger quakes that we worry about,” said Hickman. “The smaller ones get a lot of attention and remind people that we live in a tectonically active area. We study those earthquakes because the small ones tell us how earthquakes interact and how small ruptures can grow into much bigger ones. It’s all part of the puzzle we put together to try to figure out how the earthquake machine works in Northern California.”
The USGS also works to identify what areas are most at risk for extreme seismic activity, and to determine the probability of such events occurring in a discrete time frame. “Using the best science to quantify hazards, and then getting the hazards’ results into the hands of the people who need them is a big part of what we do,” said Hickman. This helps the authorities prepare for the worst by implementing appropriate building codes, providing necessary training to first responders, and developing emergency plans for dire scenarios. Earthquake simulations are an essential part of many readiness programs.
The Southern California “Shake Out,” the largest earthquake drill in the United States, takes place on the third Thursday of October each year. It provides people and government services across the state the opportunity to practice responding to problems arising in a major earthquake: power outages, mudslides, building collapses, and more. Hickman says that a similar-scale simulation will come to Northern California soon.
Thanks to collaboration and hard work between the USGS, researchers in universities across the country, and state and local authorities, our community’s knowledge and ability to respond to a major earthquake continues to improve. But what can everyday people do to prepare for a quake rivaling those that shook California to its core?
Safety and Preparedness
Hickman discussed ways that people can protect themselves before the actual earthquake hits. “If you’re a homeowner, bolting the house to the foundation, tying back water heaters…minimizing the number of things that could fall over and hurt you.” Securing large appliances, furniture, and shelving can be easily and cheaply done with straps, bolts, and latches picked up at a local hardware store. This can help minimize property damage in a quake, and maybe even avert injury or death for those inside.
It’s also important to set up at least three days — ideally a week — of water and food supplies for each family member in the event that distribution lines are disrupted. “I’ve got an earthquake kit in my front yard and in my tool shed. I have to be prepared since it’s my business,” Hickman quipped. Other items worth adding to a disaster kit are copies of important documents, cash, clothing, tools, a radio, flashlights, medicine with a first aid kit, phone chargers, fire extinguishers, and anything else used on a daily basis.
It’s also a good idea to develop a communications plan so that you and your family can contact each other. Identify someone outside of the Bay Area who can be responsible for giving and receiving messages, and to make sure that everyone is safe and accounted for. In earthquakes, while short-distance communication is often overloaded or disrupted, long-distance communication is usually less effected. Also, establish a designated meeting place in case home is not accessible.
The USGS and numerous research universities are developing the ShakeAlert system, an early warning system that can give smartphone and computer users a warning if an earthquake is sensed. These systems take information from hundreds of precise sensors placed around the state and calculate the severity and arrival time of earthquake shaking. “It could provide, when fully implemented, several seconds up to a minute or more of advance warning after the earthquake starts but before the strong shaking gets to you. That will allow people to duck, cover and hold on, it would allow trains to slow down or stop, people to stop vehicles, firehouse doors to open up, industrial processes could stop that would prevent big economic losses…surgeons could stop operations. There are lots of things people could do if they were given a few seconds to a minute of warning.” Hickman is keen to roll out this program to the greater population. “If this is funded well enough, we will be able to go to a public alert system in a few years.”
Once an actual earthquake occurs, your first priority is to protect yourself. If you begin to feel shaking, find a sturdy object such as a desk or table to hide beneath, prioritizing protecting your head and upper body above all else. Hold on to that object tightly to prevent injuries from being thrown around by the force of the shaking. If nothing else, get down next to an interior wall or a couch and cover your head and neck with your arms. If you are outside, carefully move towards open space and stay away from building exteriors, overhead power lines, and trees.
After the initial shaking, be wary of aftershocks and gas leaks. Avoid lighting candles or matches, and prepare to evacuate if any large fires occur. If someone in the vicinity is injured, keep calm and call 911 if possible. In the meantime, put direct pressure on the wound and ensure that the victim doesn’t move unless at risk of greater injury. This may seem outlandish, but yes, be aware of tsunamis. If you’re near the coast and the water is receding, immediately find higher ground, and do not return until authorities declare it is safe to do so.
There is no doubt that earthquakes pose a grave danger to our region and the state of California in its entirety. But as long as we continue to explore this powerful natural phenomenon, and ensure that our first responders and community as a whole are prepared, we have a good chance of pulling through with less damage and destruction from “The Big One.”
For more information, visit http://earthquake.usgs.gov/ and http://earthquake.usgs.gov/