What caused the New Madrid earthquakes?

In 2001 American geophysicist Mark Zoback suggested that the earthquakes were caused by fault movement precipitated by the continued release of stress at the surface from the retreat of glaciers.

What caused the New Madrid fault?

The Reelfoot rift is identified today as a subsurface system of fractures and faults in the earth's crust. New Madrid seismicity is spatially associated with the Reelfoot rift and may be produced by movement on old faults in response to compressive stress related to plate motions.

What kind of fault is the New Madrid fault?

The New Madrid seismic zone of the central Mississippi River valley has been interpreted to be a right-lateral strike-slip fault zone with a left stepover restraining bend (Reelfoot reverse fault).

What is the reason for the high concentration of earthquakes in the US midcontinent New Madrid seismic zone )?

Here we argue that the concentration of magnitude 7 or larger earthquakes in the New Madrid seismic zone of the central U.S. since the end of the last ice age results from the recent, climate-controlled, erosional history of the northern Mississippi embayment.

Could the New Madrid earthquakes happen again?

Paleoseismic evidence collected in recent decades indicates that strong "earthquake triplets" similar in magnitude to the 1811-12 temblors have occurred approximately every 500 years along the New Madrid fault and are likely to happen again.

The "Hard Shock:" The New Madrid Earthquakes.

How overdue is the New Madrid fault?

Projections. The USGS has projected that for an earthquake of magnitude 7.5 to 8.0, the probability for occurrence is approximately 7-10% over the next 50 years. For a quake of 6.0 to 7.0, the probability is 28-46% over the next 50 years.

Why might the New Madrid area be at risk for more earthquakes?

More earthquakes could strike the New Madrid area as more age-old stresses are released. Similar changes could be happening elsewhere. "We know there are other rifts under other river valleys around the country," he says. Many of those places haven't experienced earthquakes in recent history.

When was the last time the New Madrid Fault went off?

The last strong earthquake (magnitude 6.7) in the NMSZ occurred near Charleston, Missouri on Oct. 31, 1895. A magnitude 6.3 earthquake near Lepanto, Arkansas on Jan. 5, 1843 and was the next prior earthquake of this magnitude.

When was the last time the New Madrid Fault was active?

It was December 16, 1811, and it was the first of at least three very large (M7 or greater) earthquakes and thousands of aftershocks to rock the region that winter, with the last occurring on February 7, 1812.

What is the most earthquake prone state in the US?

The two states that tend to get the most earthquakes on average are California and Alaska. Other states with high amounts of seismic activity include Nevada, Hawaii, Washington state, Wyoming, Idaho, Montana, Utah, and Oregon.

What states would be affected by the New Madrid Fault?

Earthquakes that occur in the New Madrid Seismic Zone potentially threaten parts of seven American states: Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee, and Mississippi.

What is the biggest fault line in the world?

The Ring of Fire is the largest and most active fault line in the world, stretching from New Zealand, all around the east coast of Asia, over to Canada and the USA and all the way down to the southern tip of South America and causes more than 90 percent of the world's earthquakes.

What plate boundary caused the New Madrid earthquake?

Geologists are beginning to understand the answer. The New Madrid Fault Zone is part of an ancient plate boundary. In this area, the North American Plate tried to form a divergent plate boundary about 500 million years ago. The splitting stopped before new plates could form.

Is the New Madrid fault a transform plate boundary?

While the fault zones on America's west coast (such as the San Andreas) are called “transform faults,” those in which the earth's tectonic plates rub against each other, the New Madrid zone is called an “intraplate zone,” meaning that it is a weak spot in the middle of the North American plate.

Did the Ohio river flow backwards?

The first shock, estimated now at a magnitude of 7.5 to 7.9, struck New Madrid, Missouri, in the early hours of Dec. 11, 1811, and a second at 8 a.m. Settlements along the Mississippi were destroyed, people died, the river was said to run backwards and bells rang in Boston.

What caused the Mississippi river to flow backwards?

On February 7, 1812, the most violent of a series of earthquakes near Missouri causes a so-called fluvial tsunami in the Mississippi River, actually making the river run backward for several hours.

Did the Mississippi river run backwards?

Between December 16, 1811, and late April 1812, a catastrophic series of earthquakes shook the Mississippi Valley. Towns were destroyed, an 18-mile-long lake was created and even the Mississippi River temporarily ran backwards.

Is St Louis on a fault line?

And St. Louis, well over 100 miles from the fault system, is still susceptible to danger because earthquakes in the Eastern U.S. travel greater distances than their counterparts out west, thanks to the prevailing rock types in each region.

Why does Missouri have earthquakes?

The New Madrid Seismic Zone runs about 150 miles from southeast Missouri in the bootheel, through Arkansas and into Tennessee. A seismic zone is a series of imperfections, or cracks below the ground, where Earth's plates shift, causing earthquakes. The New Madrid fault line cranks out around 200 earthquakes every year.

Is Kentucky on a fault line?

Kentucky River fault system is one of a series of major regional fault systems that extends east-northeasterly across Kentucky. The western members of these fault systems are the Shawneetown and Rough Creek (discussed separately as Class C faults) fault systems in southern Illinois and western Kentucky.

Will California fall into the ocean?

No, California is not going to fall into the ocean. California is firmly planted on the top of the earth's crust in a location where it spans two tectonic plates.

How overdue is the San Andreas fault?

California is about 80 years overdue for “The Big One”, the kind of massive earthquake that periodically rocks California as tectonic plates slide past each other along the 800-mile long San Andreas fault.

What are the signs of a big earthquake coming?

A good prediction must indicate when and where an earthquake will take place. Fault segments behave the same way over time. Signs that an earthquakes may occur include foreshocks, ground tilting, water levels in wells, and the relative arrival times of P- and S-waves.