Myths & Facts
I’ve heard South Carolina sits on a fault line
There are many, many fault lines running throughout South Carolina.
Fracking causes earthquakes in South Carolina.
There is no fracking anywhere in South Carolina since there are no natural gas reserves here.
Earthquakes only happen on the West Coast of the U.S.
Earthquakes can strike anywhere, according to USGS. In fact, earthquakes east of the Rocky Mountains hit different, causing noticeable ground shaking over much farther distances. Eastern North America has older rocks which have had more time to heal. When an earthquake occurs here, many more people report feeling it because seismic waves are able to travel more effectively. Earthquakes on the East Coast also tend to cause higher frequency shaking, or higher back and forth motion, than quakes of similar magnitude in the West.
Get in a doorway when an earthquake occurs
You may have been taught that a doorway is one of the safest places to be during an earthquake. But in most cases, doorways are no stronger than the rest of the building, and they do not provide protection from flying or falling objects, which pose the greatest risk of injury to people during a quake. Instead, if you can move safely, get under a sturdy piece of furniture and hold on. Drop to your hands and knees and cover your head and neck with your arms. Learn why rescuers and researchers worldwide recommend DROP, COVER, HOLD ON as the best thing you can do to protect yourself.
Run outside if you are indoors during an earthquake
If you are indoors, stay there until the shaking stops and you are sure that it is safe to exit. Research shows that most injuries occur when people within a building move around or attempt to go outside.
The worst is over. It is time to assess damage and clean up
Do not assume that you are safe immediately after the shaking has stopped. Aftershocks can occur minutes after the first quake ends. While they are usually not as strong, they can cause additional damage and injuries. Drop, cover and hold on again in the case of aftershocks.
Dogs and other animals can "sense" when an earthquake is going to strike
Changes in animal behavior sometimes have been observed prior to earthquakes, but that behavior is not consistent, and sometimes there's no perceptible behavior change prior to an earthquake. It’s a fascinating aspect of earthquakes but at this point, only anecdotal evidence exists.
Small earthquakes keep big ones from happening
Each magnitude level represents about 30 times more energy released. It takes 30 magnitude 3s to equal the energy released in a magnitude 4, 900 magnitude 3s to equal a magnitude 5, and 729 billion magnitude 3s to equal a single magnitude 9. So while a small quake may temporarily ease stress on a fault line, it does not prevent a large temblor.
Small earthquakes almost always mean a larger earthquake is about to happen
Per, USGS, Worldwide the probability that an earthquake will be followed within 3 days by a large earthquake nearby is somewhere just over 6%. In California, that probability is about 6%. This means that there is about a 94% chance that any earthquake will NOT be a foreshock. In California, about half of the biggest earthquakes were preceded by foreshocks; the other half were not. At this time, we cannot tell whether or not an earthquake is a foreshock until something larger happens after it... so only in retrospect.
We have good building codes, so we must have good buildings
That's true -- provided you're talking about buildings constructed under current building codes. In the case of older buildings, retrofitting -- bringing the building up to modern standards -- is up to the building's owners.
Earthquakes are becoming more frequent
Research shows that earthquakes of magnitude 7.0 or greater have remained constant throughout the century and have actually decreased in recent years. However, since there are a greater number of seismological centers and instruments capable of locating many small earthquakes that went undetected in earlier years, it may seem as if there are more.
There's nothing I can do about earthquakes, so why worry about them?
It's true that earthquakes can't be stopped, but you can be prepared. You can prepare an earthquake kit (food, water, flashlight, etc.), practice "Drop, Cover, Hold On" drills at home with your family and at work, and develop an earthquake plan (where would you meet family members if you weren't together when an earthquake hit?).
Earthquake faults can open wide enough to swallow people and buildings
A popular literary device is a fault that opens during an earthquake to swallow up an inconvenient character. Gaping faults exist only in fiction. During an earthquake, the ground moves across a fault, not away from it. If the fault could open, there would be no friction. If there were no friction, there would be no earthquakes.
It must be earthquake weather!
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 (miles) below the region affected by surface weather. People tend to notice earthquakes that fit the pattern and forget the ones that don't. Also, every region of the world has a story about earthquake weather, but the type of weather is whatever they had for their most memorable earthquake.
Everyone will panic during the Big One.
A common belief is that people always panic and run around madly during and after earthquakes, creating more danger for themselves and others. Research shows that people usually take protective actions and help others both during and after the shaking. Most people don't get too shaken up about being shaken up! The Great ShakeOut earthquake drill is a great way to practice and be prepared for earthquakes.
We can predict earthquakes
There is currently no scientific way to determine when earthquakes will occur. Scientists can make statements about earthquake rates and where earthquakes are likely to occur at some future point, but they cannot calculate when and where earthquakes of certain magnitudes will strike.
Big earthquakes happen in the morning
Several recent damaging earthquakes HAVE happened in the early morning hours so many people assume that all big earthquakes happened then. In fact, earthquakes occur at all times during the day.
A volcano is causing earthquakes in South Carolina
While seismic activity around volcanoes is quite common in other parts of the world, there is no chance of a volcano erupting anywhere in South Carolina. At least, not for the next several hundred million years.
Common Earthquake Terms
The point on the Earth's surface above the point at depth in the Earth's crust where an earthquake begins.
A fault is a fracture along which the blocks of the Earth’s crust on either side have moved relative to one another parallel to the fracture. There are several types of faulting. South Carolina’s geology consists of many fault systems, which run throughout the entire state.
Foreshocks are earthquakes that precede larger earthquakes in the same location. An earthquake cannot be identified as a foreshock until after a larger earthquake in the same area occurs.
Aftershocks are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 rupture lengths distance from the mainshock. Aftershocks can continue over a period of weeks, months, or years. In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue.
A swarm is a sequence of mostly small earthquakes with no identifiable mainshock. Swarms are usually short-lived, but they can continue for days, weeks, or sometimes even months. They often recur at the same locations. State and local officials continue to research the ongoing earthquake swarm in the Elgin/Lugoff area of Kershaw County.
Scientists who study earthquakes and their causes and results.
The record made by a seismograph.
Instruments that make an automatic record of the time, duration, direction, and intensity of earthquakes.
Theory of Plate Tectonics
States that the earth’s crust is divided into a number of relatively rigid plates that collide with, separate from, and translate past one another at their boundaries, this disruption commonly results in earthquakes.
Intraplate pertains to earthquake activity (like the kind we experience in South Carolina within a tectonic plate vs. between them (interplate).
Modified Mercalli Intensity (MMI) Scale
The Modfied Mercalli Intensity Scale is commonly used in the United States by seismologists seeking information on the severity of earthquake effects.
Moment Magnitude Scale
Magnitude is the most common measure of an earthquake's size. It is a measure of the size of the earthquake source and is the same number no matter where you are or what the shaking feels like. The Richter scale is an outdated method for measuring magnitude that is no longer used by the USGS for large, teleseismic earthquakes. The USGS currently reports earthquake magnitudes using the Moment Magnitude scale.