January 20, 2010 > Stand steady on shaky ground
Stand steady on shaky ground
By Alyson Whitaker
Photos By courtesy of Joyce R. Blueford
An earthquake can be unsettling to even lifelong residents of California. With several well-known and active faults spanning the state, there is plenty of seismic activity for scientists and seismologists to track and study.
In recent weeks, the news has been peppered with reports and personal experiences of earthquakes in California and around the world. Northern California has experienced several sizable tremors, ranging from a magnitude 4.1 centered just miles from Fremont, to a 6.0 in Eureka that knocked out power to thousands of residents and was felt hundreds of miles to both north and south. Haiti recently suffered a devastating major temblor rated at 7.0 shattering most of that country's infrastructure with great loss of life.
An earthquake is caused by an abrupt shift of the earth's crust along a fracture in the earth - known as a 'fault.' When pressure and energy build along fault lines, opposing masses of rock can suddenly slip; friction of that movement releases shock waves. The result is an earthquake. Depending on the depth of the tremor, as well as the force of the slip, resulting tremors can vary from a mild shaking to widespread disaster and total destruction.
The 'hypocenter' of an earthquake is the location deep in the earth where the rupture of the fault begins. The 'epicenter' of an earthquake is the location directly above the hypocenter on the surface of the earth. Measurement of the severity of an earthquake is tracked using sensitive instruments that measure the energy released by movement of the earth's crust.
The widely used 'Richter Scale' assigns a number based on a logarithm of 10. Each whole number of the scale (1,2,3,4...) is separated by a seismic wave factor of 10 which represents an increase of over 30 times the amount of energy released. This means that an earthquake registering an intensity of 5.0 is significantly stronger than that rated 4.0. Earthquakes under 4.0 on the Richter scale are listed as "micro" or "minor" usually with little of no significant accompanying damage. Moderate, Strong, Major, Great and Epic labels are assigned to higher numbers on the scale with the expectation of increasing levels of devastation. Other measurement scales such as 'moment magnitude' are now in use as well.
While an earthquake cannot be predicted, the USGS (United State Geological Survey) uses probabilities to calculate the potential for future earthquakes. Scientists estimate that over the next 30 years, the probability of a major earthquake occurring in the San Francisco Bay area is approximately 67 percent, and 60 percent for Southern California. Rather than focus on unreliable predictions, the USGS focuses their efforts on reducing earthquake hazards and improving the safety of structures, roadways, and bridges in populated areas.
For residents of California, the same can apply. There are several faults in the Bay Area that could potentially produce a large-scale earthquake. We can't predict when the next 'Big One' will hit, but we can prepare ourselves for when it does.
FEMA offers suggestions on ways to plan ahead:
1. Check for hazards in the home-fasten shelves and heavy furniture to walls, check for defective electrical wiring or gas leaks, hang pictures and mirrors away from beds, couches, and anywhere people sit.
2. Identify safe places indoors and outdoors-'duck & cover' isn't always the best alternative. Look around and identify the safest places inside and out and regularly review with family members.
3. Have disaster supplies on hand, including flashlight and batteries, first aid kit, essential medicines, a supply of drinking water and ready-to-eat foods.
4. Develop an emergency communication plan in case family members are separated from one another during an earthquake and develop a plan for reuniting after the disaster.
If you are indoors when an earthquake strikes, a sturdy desk or table can provide cover. A door frame should be used only if it is close by and you are certain it is a strongly supported, load-bearing doorway. Stay away from windows, glass, outside doors and walls, or anything that could potentially fall on you. If you're in bed, stay put and protect your head with a pillow.
If you are outside, stay there. Move away from buildings, streetlights, and any power lines. While you may have a hard time keeping your balance during the shake, ground movement is rarely the direct cause of injury. Have a seat on the ground, and wait out the quake.
In a moving vehicle, you may not feel an earthquake at all. If you do happen to feel it, or hear word of it on the radio, stop your car in the first safe location. Verify that bridges and roadways are safe to travel before proceeding to your destination.
With a little preparation and a lot of common sense, you'll be standing steady the next time the earth starts shaking.
For more information on earthquakes and to track those in your area, visit www.usgs.gov.
Earthquake preparedness class for young children
The Math/Science Nucleus, a non-profit organization in Fremont, is offering a class to kindergartners and first graders on natural disasters. The class will focus on raising awareness of earthquake preparedness while identifying and locating active and non-active volcanoes.
Students will use shaker tables to simulate an earthquake. They will have multiple tries to build a safe structure to 'save the baby' when disaster strikes and learn critical thinking skills, helping them to identify what the dangers of an earthquake might be and determine the safest reactions. Learning to recognize potential hazards and safe spots in their surroundings will enable them to react appropriately and safely in a real danger.
Natural Disasters- Saturday Science Academy (K - 1st grade)
Saturday, January 30
1 p.m. - 4 p.m.
4074 Eggers Drive, Fremont.