On 24 April 1867, a big earthquake hit Riley County, Kansas, in the United States. The maximum Mercalli intensity was VII (Very strong), and a magnitude of 5.1 was given. It caused minor damage in Kansas, Iowa, and Missouri, according to the United States Geological Survey. It was felt across a area of 200,000 square miles (520,000 km2), even reaching Indiana, Illinois, and possibly Ohio. It was one of the biggest earthquakes in the history of Kansas.

Manhattan is close to the Nemaha Ridge, which is a long, folded rock structure with some surrounding faults. In 2016, a hazard map by the United States Geological Survey predicted a very low (1% or less) chance of a big earthquake happening in Kansas in the next year.

Background and geography
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The Humboldt Fault (red) and Midcontinent Rift System (green)
An earthquake happened in Manhattan, Kansas, close to the Kansas River and the Big Blue River. This area is close to the Nemaha Ridge, which is an old granite range with faults that likely caused the earthquake. The area also has the Humboldt Fault Zone, which acts as the eastern boundary of the range and is a important source of earthquakes in the state. This fault is a normal, or dip-slip fault, responsible for several small tremors each year, smaller than magnitude 2.7.

The Nemaha Ridge is about 50 miles east of the Midcontinent rift, a layer of basaltic rock that's very old, around 1.1 billion years. This rift (tear) stretches from Lake Superior in the north to Kansas in the south. In Kansas, the Central Kansas Uplift, with has faults, caused some small earthquakes in the late 1980s. According to Don Steeples, a geophysicist from the United States Geological Survey, earthquake activity has decreased in the Humboldt Zone but increased in the Uplift region.

The Humboldt Fault Zone, found here, is responsible for many earthquakes in Kansas. This fault goes through Permian rock and might be more complicated than people thought before. The earthquake was felt across a huge area, about 193,000 square miles (500,000 km2), although some sources listed the felt area as 300,000 square miles (780,000 km2), or 95,000 square miles (250,000 km2). This broad reach happened because of the specific geology in the region. Unlike coastal areas where earthquakes are often confined to smaller regions, in Kansas, they spread out widely due to the firm ground and their relatively shallow depth.

In February 2016, there was a earthquake that hit Oklahoma, with a magnitude of 5.1. It made the ground shake in the Manhattan area, and this was reported in the Bulletin of the Seismological Society of America. A study discovered 100 earthquakes on the Richter scale between December 1977 and June 1989 using a seismograph network. These quakes varied in size, with the strongest being a 4.0 on the Richter scale and the weakest measuring 0.8.

Damage and casualties
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Lane University shook from the earthquake
At 20:22 UTC, or around 2:30 local time, the big earthquake hit in Kansas. It was categorized as a very strong earthquake with a maximum Mercalli intensity scale of VII. It caused minor damage across a wide area, affecting 22 counties in Kansas, and injuries were reported. The earthquake caused various types of damage, such as breaking walls, knocking down chimneys, and harming buildings, even causing stones to come loose. In Manhattan, near the epicenter, clocks stopped, and residents felt electrical shocks. The following day, there was an aftershock between 3 and 4 a.m. Damage in Manhattan and other communities might have been made worse by them being low-lying valleys.

At a farm 3 miles (4.8 km) south of the city of Wamego, the earthquake caused liquefaction of the ground. To the north of Wamego, in the city of Louisville, the earthquake caused harm to horses. In both Louisville and the city of Leavenworth, chimneys falls. In Paola, the earthquake destroyed one wall in a newspaper office building. Waves were seen on the Kansas River, reaching 2.0 feet (0.6 m) in height. The city of Atchison felt two shocks, which fell lamps and bottles in a drug store, buildings shook, and water flow in rivers and creeks was disrupted.

In Emporia, there was an earthquake with a low rumbling sound, windows shook, and small boxes fell off shelves as people ran out of buildings. In Lawrence, it felt three earthquakes in just 30 seconds, causing doors and windows to shake violently, plaster to break, and a loud rumbling noise. The city of Fort Scott only trembled, while Iola had shaking houses and tableware. Holton saw items knocked off shelves, and buildings shook. Irving residents heard rumbling before severe tremors lasting 30 seconds. In Junction City, buildings shook violently, moving several inches. Kansas City experienced tables moving, cracked walls, spilled water, cracked plaster, and general panic.

In Lawrence, it felt three earthquakes in just 30 seconds, causing doors and windows to shake violently, plaster to break, loud rumbling noise, and overturned stove. Leavenworth felt three shocks, causing a man being knocked off a hayload, a rumbling noise, and stopped clocks. Lecompton's Lane University building shook, and Marysville's high school shook violently.

In Montgomery County, people in moving vehicles did not feel the earthquake. In Mound City, Ottawa, Olathe, and Oskaloosa, many houses shook. In Oskaloosa, the cupola (dome) of a new school wobbled. A train on the Pacific Railroad in Solomon shook violently, prompting evacuation. In Topeka, the ceiling of a Methodist church bent, and nearly all windows in one schoolhouse were destroyed. White Cloud felt two shocks, and Wyandotte County residents were awakened.

Reports from Iowa and Missouri describe fallen plaster in Dubuque, shaking buildings in Des Moines, and cracked plaster in Chillicothe. Dubuque, Iowa had three shocks, during which gas burners shook, there was panic among residents, rattled windows, shaken chairs, newspaper cases, and even made holes in brick walls. In St. Joseph, Missouri, windows broke, some women fainted, and a loud rumbling noise happened.

The Chicago Tribune, in its article "At Leavenworth, Kansas", said that the earthquake was a complete surprise. They described it as sudden and said that it scared everyone because earthquakes were not common in the past.

The Chicago Tribune write a article about a big earthquake in Kansas. One article called "At Kansas City" said the earthquake shook homes suddenly and made a loud noise like thunder. Another article called, "At Leavenworth, Kansas", says that the earthquake was a surprise, and people were scared.

Future threats
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The Tuttle Creek dam and reservoir in Kansas
Earthquakes are not common in Kansas. A strong one could be a big problem for the state. If an earthquake happens, it would probably happen at the Nemaha Ridge, which is still active. There is also the Humboldt Fault Zone near the Ridge. If an earthquake were to hit there, it could break the nearby Tuttle Creek Dam, releasing a lot of water and flooding the nearby area. This would put about 13,000 people and 5,900 homes in danger. Since 2013, more than 500 earthquakes have happened in the state. The United States Army Corps of Engineers found that a earthquake between 5.7 and 6.6 could make the ground under the dam turn into quicksand. That would make the dam stretch out and the top of the dam drop by up to three feet. A big earthquake could make holes in the dam, letting water go through and eventually destroying the dam. Earthquakes that might be bad for the dam happen roughly every 1,800 years. The Corps of Engineers has made the dam stronger because of this. They replaced the sand under the dam with more than 350 walls and added sensors connected to alarms to warn people nearby if there is an earthquake.

Since 2013, over 500 earthquakes have been recorded in the state, which has reawakened old fault lines. In 2016, the United States Geological Survey made maps showing the earthquake risk for the state, and they found that there is a 1% or lower chance of a big earthquake in the next year. Because Sedgwick County and Wichita could experience shaking from earthquakes that existing building codes can not handle, officials in the area have suggested changing the building codes to address this risk. Scientists at the United States Geological Survey believe that there is still a possibility of a 7.0 magnitude earthquake, possibly originating from the Nemaha Ridge where the earthquake hit.

Related pages
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* List of earthquakes

Sources
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* DuBois, S. M.; Wilson, F. W. (1978). *A Revised and Augmented List of Earthquake Intensities for Kansas, 1867–1977* (PDF). Kansas Geological Survey.
* Merriam, D. F. (April 1956). "History of earthquakes in Kansas". *Bulletin of the Seismological Society of America*. Seismological Society of America.
* Stover, C. W.; Coffman, J. L. (1993). *Seismicity of the United States, 1568–1989 (Revised): U.S. Geological Survey Professional Paper 1527*. United States Government Printing Office.
* Wasowski, J.; Giordan, D.; Lollino, P. (2017). *Engineering Geology and Geological Engineering for Sustainable Use of the Earth's Resources, Urbanization and Infrastructure Protection from Geohazards: Proceedings of the 1st GeoMEast International Congress and Exhibition, Egypt 2017 on Sustainable Civil Infrastructures*. Springer Publishing.