City Encourages Residents to Know The Facts About Earthquakes
2013-09-30 · By Editor
There are many myths and misunderstanding about earthquakes. As you prepare your family disaster response plan you should base your actions on facts, not myths. Here are 10 frequently repeated myths about earthquakes, and correct information provided by earthquake experts in responses to those myths.
Myth 10: There is nothing I can do about earthquakes, so why worry about them.
Fact: It is true that you cannot control when or where an earthquake will occur. However, you have complete control over how well you are prepared for an earthquake. Create an earthquake plan for your home and family, put together an earthquake kit (food, water, tools, etc.) and make sure all of your family members know what to do in an earthquake.
Myth 9: During an earthquake, you should get into a doorway for protection.
Fact: In modern homes, doorways are no stronger than any other parts of the structure and usually have doors that will swing and can injure you. Remember drop, cover, and hold on. During earthquakes, drop to the floor; take cover under a sturdy desk or table, and hold on to it firmly.
Myth 8: During an earthquake, the earth cracks open and people, cars, and animals can fall into those cracks.
Fact: The earth does not crack open like the Grand Canyon. The earth moves and rumbles and, during that movement, small cracks can form. The usual displacements of the earth during an earthquake are caused by up-and-down movements, so shifts in the height of the soil are more likely than chasm-like cracks.
Myth 7: Animals can sense earthquakes and give advanced warning.
Fact: Animals may be able to sense the first low-frequency waves of an earthquake that occurs deep within the earth, but the damage-causing primary and secondary waves follow just seconds behind. Animals do not make good earthquake warning devices.
Myth 6: Big earthquakes always happen in the early morning.
Fact: Several recent damaging earthquakes have occurred in the early morning, so many people believe that all big earthquakes happen then. In fact, earthquakes occur at all times of day. The 1933 Long Beach earthquake was at 5:54 pm and the 1940 Imperial Valley event was at 9:36 pm. More recently, the 1989 Loma Prieta event was at 5:02 pm.
Myth 5: It’s hot and dry — earthquake weather!
Fact: Many people believe that earthquakes are more common in certain kinds of weather. In fact, no correlation with weather has been found. Earthquakes begin many kilometers below the region affected by surface weather. Some people tend to notice earthquakes that fit the pattern and forget the ones that do not.
Myth 4: Someday there will be beachfront property in Arizona.
Fact: The Ocean is not a great hole into which California can fall, but is itself land at a somewhat lower elevation with water above it. The motion of plates will not make California sink. California is moving horizontally along the San Andreas Fault and up around the Transverse Ranges (coastal California Mountains).
Myth 3: We have good building codes so we must have good buildings.
Fact: The tragedy in Kobe, Japan, one year after the Northridge earthquake, painfully reminds us that the best building codes in the world do nothing for buildings built before that code was enacted.
Myth 2: Scientists can now predict earthquakes.
Fact: Scientists do not know how to predict earthquakes at this time; however, probabilities can be calculated for potential future earthquakes. For example, scientists estimate that during the next 30 years the probability of a major earthquake occurring is 67 percent in the San Francisco Bay Area and 60 percent in Southern California.
Myth 1: Small earthquakes are helpful because they release pressure and prevent larger earthquakes.
Fact: Some people believe that smaller earthquakes “let off steam”. This is not true. Moderate earthquakes may actually be precursors of larger earthquakes. The Richter Scale measures the magnitude of earthquakes, which is the amount of energy released. An increase of one number indicates a tenfold increase in the amount of energy released. A 6.0 quake releases 10 times more energy than a 5.0 earthquake. A large magnitude earthquake such as a 7.0 on the Richter scale, releases 100 times more energy than a medium magnitude 5.0 earthquake.
Sources: California Geological Survey/California Geology, USGS, Arkansas Center for Earthquake Education and Technology Transfer, Governor’s Office of Emergency Services, Federal Emergency Management Agency, National Science Foundation, Southern California Earthquake Center, American Red Cross, Center for Earthquake Research and Information/University of Memphis.