The New Madrid, Missouri Earthquakes, 1811-1812

When one thinks of earthquakes in the U.S., we often think of the west coast. But, on a U.S. earthquake hazards map, there is a big bull’s eye in the Midwest along the Mississippi River, centered on the town of New Madrid, Missouri. According to the U.S. Geological Survey (USGS) this area, the New Madrid seismic zone has “ repeatedly produced sequences of major earthquakes, including several of magnitude 7 to 8, over the past 4,500 years.”

The most famous New Madrid earthquakes occurred from December 16, 1811, through February 7, 1812. The three main earthquakes measured 7.3-7.5 on the Richter scale. Aftershocks persisted through 1813.

According to the USGS:

1811, December 16, 08:15 UTC Northeast Arkansas – the first main shock

2:15 am local time

Magnitude ~7.5

This powerful earthquake was felt widely over the entire eastern United States. People were awakened by the shaking in New York City, Washington, D.C., and Charleston, South Carolina. Perceptible ground shaking was in the range of one to three minutes depending upon the observers location. The ground motions were described as most alarming and frightening in places like Nashville, Tennessee, and Louisville, Kentucky. Reports also describe houses and other structures being severely shaken with many chimneys knocked down. In the epicentral area the ground surface was described as in great convulsion with sand and water ejected tens of feet into the air liquefaction).

During the February 7 earthquake, “Large waves (seiches) were generated on the Mississippi River by seismically-induced ground motions deforming the riverbed. Local uplifts of the ground and water waves moving upstream gave the illusion that the river was flowing upstream. Ponds of water also were agitated noticeably.”

The New Madrid seismic zone is underlain by the Reelfoot Rift, a large fault zone with mainly horizontal movement. It is speculated that this rift was formed about 750 million years ago during the breakup of the supercontinent Rodinia. The Reelfoot Rift failed to split the continent, but remains a weak area in Earth’s crust. From time to time, pressure from the movement of tectonic plates causes movement on this weak area resulting in earthquakes.

The USGS “concludes that the New Madrid Seismic zone is at significant risk for damaging earthquakes that must be accounted for in urban planning and development. A fundamental problem is the lack of knowledge concerning the physical processes that govern earthquake recurrence in the Central US, and whether large earthquakes will continue to occur at the same intervals as the previous three clusters of events. ”

To read more, including eyewitness accounts, and a summary of 1811-1812 New Madrid earthquakes sequence, go to:

Related stories:

Where the Next Big American Earthquake and Tsunami Might Occur

The Great Arizona-Sonora Earthquake of 1887

Earthquake swarm in NW AZ explained

Since March, 2016, northwestern Arizona has experienced on-going earthquake activity. To date, there have been 57 earthquakes, the largest of which registered a magnitude of 3.8.

These earthquakes are not unexpected according to the Arizona Geological Survey. They are just now being detected because of enhanced instrumentation deployment.

Northwestern Arizona is on the southern end of a seismic belt that stretches from Montana and Idaho, through Utah and into Arizona. For the past 15 million years, the crust in this area has been stretching and stretching causes faulting and earthquakes.

The Arizona Geological Survey has a 4-minute video which explains what is happening:

Field Guide – Oak Creek-Mormon Lake Graben Northern Arizona

The Oak Creek-Mormon Lake Graben lies between Flagstaff and Sedona, Arizona. The Arizona Geological Society and geologist Paul A. Lindberg have produced a 13-page field guide to the geology of the area (shown on the map below).

This geologic field trip guide circumnavigates a loop of ~120 miles from Flagstaff to Sedona along Highway 89A and returns to Flagstaff along the Lake Mary Road. The guide contains many illustrations and photographs and may be downloaded from:

Lindberg introduces us to the local geological setting:

“The Oak Creek-Mormon Lake graben (a rift valley formed by extension of the earth’s crust) has been faulted into the southwestern margin of the Colorado Plateau as basin and range crustal extension has migrated eastward across Western U.S. over time. The graben may be as young as 2-3 million years old, based upon the youthful appearance of numerous V-shaped canyons (Oak Creek, West Fork, Munds, Woods and Rattlesnake Canyons) that cut the minimally eroded original surface of the largely basalt covered core of the graben. That morphology is in sharp contrast to more maturely eroded landforms along the northeast margin of 10 Ma Verde graben near Sedona. Timing of the genesis of the Oak Creek-Mormon Lake graben may be contemporaneous with the main eruptive cycle of San Francisco Peaks north of Flagstaff, Arizona.”

The 12 geologic stops focus on recent faulting and the encroachment of Basin and Range extensional structures on the Colorado Plateau. Each stop is detailed in the text, which is amply illustrated with photographs and colored geologic sketches.

Oak Creek Graben map

Arizona Geology e-magazine for summer 2013 now online

The Arizona Geology Survey has just released its summer, 2013, issue of Arizona Geology which features seven articles.  See the whole issue at

Most interesting to me is the article: Ground-Source Geothermal Heating and Cooling: Sustainable and Affordable Energy for Arizona and the U.S.  The article begins:

“This past August 12th was the first day of the new school year for ~ 1,000 students at Lookout Mountain Elementary School in Phoenix, Arizona. The high temperature that day was a torrid 109 degrees Fahrenheit while inside the newly constructed 50,000 square foot wing of the school, temperatures were a balmy 76 degrees Fahrenheit, thanks to a new ground-source geothermal system that exchanges heat with the cooler earth hundreds of feet below the ground surface.”

The other articles:

Arizona Seismic Update – January – July 2013

“The Arizona Broadband Seismic Network documented over 50 earthquakes in Arizona from January to July 2013. The quakes were mostly located in northern Arizona and were at depths ranging from 1.4 to 26 km (0.9 to 16.25 miles depth)”

Earthquake Shakes North Rim Area

“On July 7that 1:38 MST, a magnitude 3.5 earthquake shook the towns of Fredonia, Jacobs Lake, and Havasu . The earthquake was followed by a series of aftershocks, with two registering Md ~ 2.0 and several in the 1.0 range.”

Digitizing, Cataloging, and Publishing Arizona’s Mining Legacy Online: Mine Maps, Reports, and Photographs

“In 2011, the financially troubled Arizona Department of Mines and Mineral Resources (ADMMR) and the Arizona Mining and Minerals Museum shuttered their doors. The Arizona Geological Survey (AZGS) received the Department’s maps, photos and manuscript collections. That year, AZGS began a comprehensive inventory of the 30 archival collections, creating finding aids1 for the more than 10,000 folders, 6,000 maps, and 7,000 photographs.”

Update on the STATEMAP mapping program in Arizona

“The STATEMAP program is a component of the National Geologic Mapping Act of 1992. STATEMAP is a matching fund program whereby State general funds are matched one-to-one by federal funds to support geologic mapping by the states. The Arizona Geological Survey (AZGS) has participated in the STATEMAP program since its inception, and has produced 1:24,000-scale geologic maps of a large fraction of the State with funding from this program.”

Making Geologic Maps with GIS

“Geologic map production begins in the field. Geologists spend several months traversing pre-defined areas of Arizona’s landscape to collect geologic information about that area. Geologists collect qualitative and quantitative information in the form of observations in a field notebook or on a topographic map. Geologists use a GPS (global positioning system receiver) to identify observation locations.”

Summary of oil and gas activity in Arizona – January to June 2013

Besides oil & gas, this article provides brief information on drilling for carbon dioxide, CO2 sequestration, geothermal energy, and potash exploration.

Check it out.

Earthquakes shake Morenci, Arizona area

During October, six earthquakes, ranging from 2.5- to 4.1-magnitude, occurred about 25 miles north-northeast of Morenci in Greenlee County, east-central Arizona. These earthquakes were recorded by several seismographs around Arizona, including one in Tucson. In addition, there have been swarms of lesser magnitude earthquakes in the area according to the Arizona Geological Survey (AZGS). AZGS has a short article on these recent earthquakes here. The article includes maps and seismograph records.

According to Wallace (1989) “The background seismicity level for southern Arizona is quite low, especially compared to California. The two most seismically active regions in southern Arizona are the southeastern corner of the State, extending north from Douglas along the New Mexico border to the Clifton-Morenci area, and the southwestern corner south of Yuma along the Mexico-Arizona border.”

Just why earthquakes occur in the Morenci area is subject to speculation. No faults have been positively identified, but the topography suggests that a fault exists in the area. The Morenci area has long been seismically active. In May of 2010, 12 earthquakes ranging from Md 2.0 to 3.5, and 5 events below Md 2.0 occurred near the area of recent earthquakes.

Arizona is divided into two main physiographic provinces. In the northeast is the high-elevation Colorado Plateau characterized by mainly flat-lying sediments. The southwest part of the state is the Basin & Range province, lower in elevation, and characterized by long, thin mountains ranges separated by fault-bounded valleys. The Basin & Range topography is the result of crustal stretching during the past 20 million years.

Separating the Colorado Plateau from the Basin & Range, is the so-called Transition Zone which runs diagonally through Arizona from the northwest corner to the southeast corner. This area is characterized by faults and marks the boundary between the zone of crustal extension and the more stable plateau. The Morenci area earthquakes occur in this transition zone and may reflect continued crustal adjustment to the on-going extension.

UPDATE: A magnitude 3.4 earthquake hit just before 1a.m.  this morning, November 1, about 22 miles NNE of Morenci, in eastern Arizona.


The Great Arizona Shakeout October 18

At 10:18 am on Thursday, October 18, more than 35,000 school children in hundreds of classrooms across Arizona, will drop, cover, and hold on during Arizona’s first statewide Great Arizona Shakeout earthquake preparedness drill.  They will be joined by thousands more in state and federal offices, tribal communities, civic groups, and businesses and by more than 13 million nationwide (most in California).

Each year hundreds of earthquakes occur in Arizona.  Most go unfelt, but the potential for rare, life-threatening, large magnitude earthquakes exists.   Arizona’s largest earthquakes in 2011, of magnitude 3.7 and 3.6, occurred near Clarkdale in central Arizona.  Faults in Arizona, surrounding states and Mexico are capable of damaging earthquakes up to magnitude 7.5 that could cause strong ground shaking across Arizona.

During an earthquake the greatest immediate danger in most homes and buildings is from flying or falling items – ceiling tiles, furniture, pictures, lights, mirrors, ceiling fans, and other items. Lessons learned from the 2-minute ShakeOut “Drop, Cover and Hold On” exercise can protect you, your family or students from serious injury.

ShakeOut drills inform people at school, work and home how to prepare for and survive the next damaging earthquake.

Drop to the ground;

Take Cover under a sturdy table or desk if possible and protect your head and neck;

Hold On until the shaking stops.

To participate officially, go to or if you are not in Arizona, go to   This exercise has become international.

See also:

Arizona is earthquake country

Earthquake videos from Arizona Geological Survey

Arizona earthquakes, 1852-2011, a video time line

Arizona earthquakes numbers saw a large increase in 2011

Where the Next Big American Earthquake and Tsunami Might Occur

The Great Arizona-Sonora Earthquake of 1887

Arizona is earthquake country

The Arizona Geological Survey has just released a new, well-illustrated 44-page book that can be downloaded for free (8Mb) : Arizona is earthquake country.


The book is intended as a guide on how to prepare for and minimize damage from the ground shaking that accompanies earthquakes. It also explains the geology of earthquakes and why they occur.

Here is the AZGS press release:

Young, active faults exist in and around Arizona. The northern Arizona Seismic Belt, which bisects Coconino County, hosts the greatest concentration of active faults in the state and is the most seismically active region in Arizona. Some faults, such as the Lake Mary Fault just south of Flagstaff, are capable of large magnitude earthquakes, up to magnitude 7. Yavapai, Mohave, Yuma, Pima, Cochise, Graham, and Greenlee County all host faults capable of delivering moderate to large seismic events, too. And large earthquakes on faults from surrounding states and Mexico, including California’s San Andreas fault system, are capable of damaging homes and infrastructure and threatening lives here in Arizona.

“Arizona is Earthquake Country” includes a seven-step earthquake safety guide that shows how to prepare your family and home in advance of an earthquake; how to behave during an earthquake – whether indoors or out; and how to deal with damage and related issues immediately following an earthquake.

The booklet provides a primer on the nature and geology of earthquakes in Arizona, describes six prominent faults, and revisits three major historic earthquakes that impacted the state. Instructions on how to use the U.S. Geological Survey’s online earthquake probability tool to establish the risk of a damaging earthquake in your community are also provided. Sections on monitoring earthquakes, earthquake resources – including online resources, and a glossary, round out the text.

This earthquake preparedness guide is released just in time to complement Arizona’s first-ever Great Arizona ShakeOut, a two-minute “Drop, Cover, and Hold On” earthquake drill that can minimize personal injuries and save lives. Scheduled for 10:18 a.m. on October 18th, enrollment in the ShakeOut drill is open to all, but K-12 schools are particularly encouraged to participate; for online enrollment visit the Register Here! page. To date, more than 13,300 have enrolled in ShakeOut.

Citation: Arizona Geological Survey, 2012, Arizona is Earthquake Country. Down-to-Earth #21, 44p.

Besides the features mentioned in the press release above, the book also discusses how we measure the magnitude of an earthquake; it’s not the old Richter Scale anymore. Links to additional resources are given at the end of the book. For instance, for teachers in middle and high school, there is a link for earth science lesson plans and activities. There are also several links to earthquake websites maintained by government and universities.


Earthquake videos from Arizona Geological Survey

Most earthquakes in Arizona are low magnitude and go unnoticed.  However, there is  potential for a big one.  The Arizona Geological Survey has several videos featuring earthquakes in and near Arizona.  The newest is a time-lapse animation of the Brawley earthquake swarm that occurred on 26-29, August, 2012. Brawley is in southern California, just south of the Salton Sea.

To see this video go to:

That link also contains several other earthquake-related videos (4 to 6 minutes long) so scroll down the page and you will see:

Earthquakes in Arizona

Time-lapse video animation of earthquakes in and around Arizona from 1852 to 2011. The apparent increase in seismic events in the latter part of the 20th century and early 21st century stems from improved seismic monitoring.  It is interesting to see where the most earthquakes occur.

Lake Mary Fault

The Lake Mary Fault, located immediately south of Flagstaff, Arizona, represents the greatest earthquake hazard to the more than 70,000 people of Flagstaff and environs. Dr. David Brumbaugh, Arizona Earthquake Information Center (AEIC) at Northern Arizona University, narrates the, “Lake Mary Fault — Potential Earthquake Threat to Flagstaff, Arizona.”

Little Chino Fault and Big Chino Fault

Filmed on location in Chino Valley, two separate  six minute videos describe the geometry and timing of seismic activity on these faults. This is an active fault area with a moderate recurrence rate on the order of tens of thousands of years. It is capable of yielding earthquakes in the range of magnitude 6 to 6.5 and presents a hazard to residents of Chino Valley and nearby Prescott, Arizona.

Earthquake Monitoring in Arizona, the role of the Arizona Integrated Seismic Network

Arizona has earthquakes. Geologist Dave Brumbaugh and seismic technician Lisa Linville, both of the Arizona Earthquake Information Center (Northern Arizona University), describe the role of the Arizona Integrated Seismic Network in monitoring earthquake activity in the Grand Canyon State. And Lisa deconstructs one of the broadband seismic stations that form the backbone of the system.

The 1887 Sonoran Earthquake

On 3 May 1887, a magnitude 7.2 earthquake rippled across Sonora, Mexico, and southern Arizona. Phil Pearthree, Chief of the Environmental Geology division of the Arizona Geological Survey, revisits that event in this video. The earthquake killed dozens of people and damaged or destroyed several hundred structures. A similar event today would disturb and disrupt population centers in northern Sonora and southeastern Arizona and New Mexico.

For more information on the 1887 earthquake, see my post: The Great Arizona-Sonora Earthquake of 1887

For more information on earthquakes and other geologic hazards, visit the AZGS Geologic Hazards Center:

Stephen Hawking, the big bang, invasion of aliens from outer space, the end of the world, and what’s beneath America, review of a Discovery Channel DVD

The Discovery Channel’s Curiosity series of DVD programs can be controversial, entertaining, and enlightening.

The DVD I watched had five programs (total length 198 minutes):

Did God Create the Universe?

This program presents Stephen Hawking’s view of the universe. It follows the history of our understanding of natural phenomena, such as eclipses, from religious superstition to a physical explanation. Hawking believes our universe started with a big bang, it sprang from nothing. Before the big bang there was nothing, including no time and no cause and effect. For Hawking, there is no God, no heaven, no afterlife.

In a separate program on the DVD, a panel of scientists and theologians discuss Hawking’s view. They discuss the concept of multiple universes, and conclude that science can neither prove nor disprove the existence of a creator.

Alien Invasion: Are We Ready?

This program, narrated by actress Michelle Rodriguez, features scientists and military strategists, first discussing the probabilities that some intelligent alien species exist, then speculating on how the invaders would go about getting rid of humans. If these people were the aliens, they would first disable our communications and other electronics with an electro-magnetic pulse (EMP), then kill many people in coastal areas by causing very large tsunamis. They would finish us off with biological warfare. It’s the stuff of good science fiction stories.

What’s Beneath America?

This program, narrated by Martin Sheen, is about the geology and natural resources of North America. It discusses plate tectonics, mountain building and how some of our large deposits of gold, oil, coal,and iron formed. And they got the geology right.

How the World Will End

The title of this program, narrated by Samuel L. Jackson, is a bit of hype, they destroy just North America, not the world. The program speculates on five types of natural disasters.

1) California is destroyed by an ARkStorm (spelled correctly, and yes, I never heard that term before.) Basically a mega-storm with very strong hurricane-force winds, lasts about a month and dumps 10 feet of water on California, causing flooding and land slides. This kind of storm is purely speculative. See an explanation from the U.S. Geologic Survey here.

2) Asteroid impact. This scenario features Meteor Crater (aka Barringer Crater) in Arizona as an example of a “small” impact. The program explains the consequences of a really big strike. The program claims that children today have a 1 in 20 chance of witnessing a really big strike. They fail to mention how they came up with that number.

3) Mega-earthquake in mid-west along the New Madrid fault on the Mississippi River. This program recounts the earthquakes that occurred between December 1811 and February, 1812, all with strengths estimated to be between 7.8 to 8.1. These earthquakes are the strongest to hit the eastern U.S. The program goes on to speculate what could happen if an even bigger one hits. The program puts the odds of this happening within 50 years at 1 in 10. Again they don’t explain how the number was derived.

4) The eastern seaboard of the U.S. is destroyed by a giant tsunami precipitated by a major volcanic eruption in La Palma, Canary Islands. Odds of happening 1 in 1,000, same caveat.

5) Yellowstone super volcano explodes. I wrote about this one last year (see The Yellowstone Super Volcano). This volcano tends to have a major eruption every 600,000 years on average. It has been 640,000 years since the last major eruption. That one covered about half of the U.S. with volcanic ash.

These programs are interesting and well-made. They show very good animations, but tend to overuse stock footage of disaster scenes. The programs are well-worth watching.

The DVD is available from the Discovery Channel here.

For more on the nature of the universe and religion versus science, see my reviews of two other works:

The Unobservable Universe by Scott Tyson

Religion versus Science by Ron Frost

See all my book and DVD reviews here.

Is global warming causing more earthquakes?

The allegation: global warming is melting ice caps and glaciers, thereby unloading weight. This causes an isostatic readjustment of the Earth’s crust which results in earthquakes.

The reality according to the U.S. Geological Survey:

We continue to be asked by many people throughout the world if earthquakes are on the increase. Although it may seem that we are having more earthquakes, earthquakes of magnitude 7.0 or greater have remained fairly constant.

 A partial explanation may lie in the fact that in the last twenty years, we have definitely had an increase in the number of earthquakes we have been able to locate each year. This is because of the tremendous increase in the number of seismograph stations in the world and the many improvements in global communications. In 1931, there were about 350 stations operating in the world; today, there are more than 8,000 stations and the data now comes in rapidly from these stations by electronic mail, internet and satellite. This increase in the number of stations and the more timely receipt of data has allowed us and other seismological centers to locate earthquakes more rapidly and to locate many small earthquakes which were undetected in earlier years. The NEIC now locates about 20,000 earthquakes each year or approximately 50 per day. Also, because of the improvements in communications and the increased interest in the environment and natural disasters, the public now learns about more earthquakes.

 According to long-term records (since about 1900), we expect about 17 major earthquakes (7.0 – 7.9) and one great earthquake (8.0 or above) in any given year.

See a video of the apparent increase of earthquakes in Arizona due to the increase in number of seismic stations: Arizona earthquakes, 1852-2011, a video time line