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 , 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
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 ancient granite range with faults that likely caused the earthquake.
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 , although some sources listed the felt area as , or . 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 over 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
At 20:22 UTC, or 2:30 local time, the big earthquake hit in Kansas, and injuries were reported. It caused minor damage across a wide area, affecting 22 counties in Kansas. The earthquake caused various types of damage, such as breaking walls, knocking down chimneys, and harming buildings, even causing stones to come loose. The following day, there was an aftershock at 4 am. Damage in Manhattan and other communities might have been made worse by them being low-lying valleys.
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.
In Montgomery County, people in moving vehicles didn't feel the earthquake. In Mound City, Ottawa, Olathe, and Oskaloosa, many houses shook. In Oskaloosa, the cupola (dome) of a new school wobbled.
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.
Reaction
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.
Future threats
Kansas doesn't usually have earthquakes, a strong one could be a big problem. It's most likely to happen along the Nemaha Ridge, which is still active. There's also the Humboldt Fault Zone near Manhattan, which is just 12 miles from the Tuttle Creek Lake.