The New Madrid fault is a seismic zone located in the central United States, stretching from Arkansas to Illinois. It is a unique and complex system that has puzzled geologists for years. In this article, we will explore what kind of fault the New Madrid is and how it differs from other types of faults.
What Is a Fault?
A fault is a fracture or break in the Earth’s crust where two blocks of rock move past each other. These movements can cause earthquakes, which are sudden and violent shaking of the ground caused by the release of energy stored in rocks.
Types of Faults
There are three main types of faults – normal, reverse, and strike-slip.
- Normal Fault: This type of fault occurs when the hanging wall moves downward relative to the footwall. Normal faults are caused by tensional forces that stretch or pull apart the Earth’s crust.
- Reverse Fault: This type of fault occurs when the hanging wall moves upward relative to the footwall.
Reverse faults are caused by compressional forces that squeeze or push together the Earth’s crust.
- Strike-Slip Fault: This type of fault occurs when two blocks move horizontally past each other. Strike-slip faults are caused by shear forces that push or pull rocks in opposite directions along a vertical plane.
New Madrid Fault
The New Madrid fault is a complex system that does not fit neatly into any one category. It consists of multiple faults that intersect at different angles, making it difficult to determine which type of fault it is.
However, researchers have identified some characteristics that make the New Madrid unique:
- Intraplate: The New Madrid is an intraplate system, meaning it is located within a tectonic plate rather than at the edges where most faults occur.
- Deep: The New Madrid reaches deeper into the Earth’s crust than many other faults. This means it can generate larger earthquakes that are felt over a wider area.
- Cyclic: The New Madrid has a history of generating multiple earthquakes in relatively short periods of time. For example, in the winter of 1811-1812, the New Madrid produced four earthquakes measuring greater than magnitude 7 within a three-month period.
The Big One?
There has been much speculation about whether the New Madrid fault could produce an earthquake as large as “the big one” predicted for the San Andreas fault in California. While it is certainly possible, there are some factors that make this scenario less likely.
For one thing, the rocks in the central United States are older and colder than those on the West Coast. This means they are less likely to store energy and more likely to release it gradually over time.
Additionally, building codes and earthquake preparedness have improved significantly since the last major earthquake on the New Madrid fault in 1812. This means that even if a large earthquake were to occur, the damage and loss of life would be much less severe than it was two centuries ago.
In Conclusion
The New Madrid fault is an enigmatic seismic zone that defies easy classification. While it may not be as famous as its West Coast counterparts, it is still an important area of study for geologists and seismologists alike. By understanding what kind of fault the New Madrid is and how it differs from other types of faults, we can better prepare for potential earthquakes and mitigate their impact on people and infrastructure.