Earthquakes are usually associated with faults in the surface of the Earth. So the identification of these fault lines helps in identifying regions prone to earthquakes.
According to the United States Geological Survey (USGS), 39 out of the 50 American states are vulnerable to seismic activity in varying degrees.
Fault lines play a significant role when it comes to identification of regions vulnerable to seismic activities. Basically, a fault is a fracture or discontinuity in the rock structure, typically characterized by significant displacement. The line of intersection, which marks the separation of this fault plane and the surface of the Earth, is known as the ‘fault line’. These lines are used by geologists to forecast earthquakes, as they help in determining the vulnerability of various regions to seismic movements.
Fault Lines in the US
Every region has a government sponsored geological organization which keeps a track of various physical occurrences in that particular region. In the United States, the US Geological Survey (USGS) is the premier geological body. Similarly, each of the American states have a state government-sponsored geological organization affiliated to the USGS, which keeps a track of geological alterations occurring in the region. These organizations prepare a map of the region and mark all the fault lines lying there. On these geological maps, these lines are marked as black lines. In some of these maps, fault lines belonging to the buried faults are not shown. However, they do find a place in technical publications of the premier organizations dealing in geological studies. A map which shows these fault lines can tell you whether you reside in an area prone to earthquakes or not.
Major Fault Lines
One should have a sound knowledge of various aspects of geology to recognize fault lines on the surface of the planet. Some of these lines, especially the ones that are on the surface of the Earth, are obvious. But there are others which lie deep within the Earth’s crust, obscured by a thick layer of soil, such that you might not even realize that you have been living in a fault zone all this while. In the lengthy list of fault lines in the country, the major ones are the New Madrid fault line, Rampo fault line, etc.
New Madrid Fault Line: The New Madrid fault line has recorded over 4000 earthquakes of various scales over the last four decades. Also referred to as the New Madrid Seismic Zone, this region is one of the most vulnerable region in the United States. Earthquakes in this region directly affect a range of states including Illinois, Missouri, Tennessee, Indiana, etc.
Rampo Fault Line: The Rampo fault line runs over a distance of 187 miles between the Appalachian Mountains and the Piedmont area. Earthquakes in this fault line can have devastating effects on states like New York, New Jersey, and Pennsylvania.
Ridgefield Fault Line: One of the latest additions to the list is the Ridgefield fault line, which is believed to have been formed around 250 million years ago. An Earthquake in this zone can result in severe damage to Connecticut and the surrounding regions.
Denali Fault Line: In Alaska, the Denali fault line spans the state right through the Alaskan range, before entering Canada. The trench formed by this fault is most often filled by glaciers. If you look at the satellite image, this fault line looks like a man-made canal in the Alaskan range.
San Andreas Fault Line: Spanning the state of California, from Cape Mendocino to the Mexican border, the San Andreas fault line divides the state into two halves. It runs parallel to the coast of the United States and is prone to a number of earthquakes, thus making this region quite active in terms of seismic movements.
One has to take a note of the fact that even though fault lines help in determining whether the region is prone to earthquakes or not, they actually can’t predict earthquakes. In any given fault line, an earthquake can occur at any point of time―right from this very moment to ten years from now.