Kansas Earthquakes
Preston Johnson 
Spring 2008
ES 767 Global Tectonics
Prof. James S. Aber, Instructor

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Table of Contents

Abstract

Introduction

Nemaha Ridge

Damage Potential

Small Fault Events

Conclusions

References

 

Abstract

Mountains, earthquakes, fault lines, rift zones. These terms are usually associated with places such as Colorado, California, east Africa, not with Kansas. The fact is, Kansas has all of these, but even most natives of the state are not aware of these geologic phenomena. Kansas has had many earthquakes in the past, although in comparison to the west coast, they are relatively small. Moderate to large earthquakes are possible in Kansas.

 

Earthquake Risk

Map of earthquake risk. From the Kansas Geological Survey Public Information Circular 3.  http://www.kgs.ku.edu/Extension/image/earthquake3.html

 

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Introduction


The largest earthquake recorded in Kansas was on April 24, 1867 near Manhattan, and was an estimated magnitude 5.5. This caused chimneys to topple, walls and foundations to crack, sand geysers, and a 2 foot wave on the Kansas River. According to the Kansas Geological Survey, at least 125 earthquakes were recorded between 1867 and 1989. Most of these were microearthquakes, which are defined as earthquakes that are too small to feel.

 

Historical earthquakes in Kansas, prior to 1977

Earthquakes located throughout Kansas, though most in Geary, Riley, and Pottawatomie

Image from Kansas Geological Survey http://www.kgs.ku.edu/Publications/pic3/pic3_4.html

 

 

 

Kansas EarthquakesMicroearthquakes recorded by the Kansas Geological Survey between August 1977 and August 1989 are size-coded by local magnitude. The largest event had a magnitude of 4.0 and the smallest had a magnitude of 0.8 on the Richter scale. From Kansas Geological Survey Public Information Circular 3.  http://www.kgs.ku.edu/Extension/image/earthquake7.html

 

Magnitude Scales Approximate comparison for the U.S. Midcontinent of Modified Mercalli and Richter Scales at locations very near the epicenter. From Kansas Geological Survey Public Information Circular 3. http://www.kgs.ku.edu/Extension/image/earthquake5.html

 

Although many micro-earthquakes occur at various small scale faults, most of the seismic activity that occurs in Kansas is attributed to two major geologic structures; the Central Kansas Uplift, and the Nemaha Ridge/Humboldt Fault Zone (NRHF), and to a lesser extent, the Mid-continent rift zone.

 

Major Tectonic Structures in Kansas

 

Regional tectonic features

Image from Kansas Geological Survey http://www.kgs.ku.edu/Extension/image/earthquake8.html

 

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Nemaha Ridge

Nemaha Ridge is a buried granite mountain range that trends northeast and extends from near Omaha, Nebraska to Oklahoma City, Oklahoma. Formed about 300 million years ago during the Pennsylvanian period, this structure separates the Salina and Sedgwick basins from the Forest City and Cherokee basins of eastern Kansas.

 

Map showing the relative locations of basins and uplifts deep beneath the surface of Kansas.  

Anadarko basin in west, Salina basin in north central, Central Kansas uplift between, cherokee basin in southeast Image from Kansas Geological Survey http://www.kgs.ku.edu/Publications/Oil/primer09.html

 

Nemaha Ridge is a high-angle, reverse fault that is generally down-to-the-east. Near the Oklahoma line, vertical displacement decreases and reverses to down-to-the-west. Post-Mississippian erosion removed over 1000 ft of Lower Paleozoic strata, exposing the Precambrian basement. This was overlain by Middle and Upper Pennsylvanian strata. (McBee 2003) Areas in northeast Kansas and southeast Nebraska were also subjected to Quaternary glacial wear and deposition.

 

 

Eastern edge of Nemaha Ridge (in background) south of Alma, KS

 

 

Eastern edge of Nemaha Ridge along Interstate 70, north of Alma, KS

The Humboldt Fault lies beneath the area of the tree line/creek bed.

 

Exposed layers of Shale in a road cut on Nemaha Ridge

 

 

Looking west from the top of Nemaha Ridge near Manhattan

 

Nemaha Ridge is bounded by several active fault zonesThe largest of these faults is the Humboldt fault zone. The Humboldt fault is a strike-slip fault that forms the eastern boundary of the Nemaha Ridge, lying east of Manhattan, and west of Wamego.

 

older rocks are mapped in the eastern parts of the state, younger to the westThe ascending and descending arrows represent the NRHF zone
Image from Kansas Geological Survey http://www.kgs.ku.edu/Publications/Oil/primer09.html

 

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Damage Potential

To structures such as major dams and power plants, even a low-probability earthquake has to be taken seriously. Lying only 12 miles from the Humboldt Fault, the Tuttle Creek Dam has become a subject of study by seismologists at the U.S. Army Corps of Engineers. They contend that the smallest earthquake that could potentially cause significant damage is a magnitude 5.7 earthquake. With a predicted probability of occurrence of about once in 1,800 years, it should not cause total failure of the dam. A magnitude 6.6 earthquake however, “would cause the sand deposits under the dam to liquefy, or turn to quicksand, and lose their ability to support the dam. This, in turn, would allow the base of the dam to spread and the top to drop, and cracking would significantly reduce the ability of the dam to hold water.” The predicted probability of occurrence for this size of event is about once in 10,000 years. (KGS 2001)

Image from Kansas Geological Survey http://www.kgs.ku.edu/Publications/GeoRecord/2001/vol7.3/Page1.html

 

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Small Fault Events

Although the three major tectonic areas tend to be the major contributors to the earthquake activity in Kansas, smaller, and less well known faults can cause minor earthquakes.

Generalized fault framework of the area encompassing the Nemaha zone, which lies between, and is terminated by, two northwest-trending, left-lateral megashears, the Central Plains (to the north) and the Oklahoma (to the south). (McBee 2003) http://www.searchanddiscovery.net/documents/2003/mcbee/images/mcbee.pdf

 

This point is illustrated in the earthquake that struck Kansas City, Kansas in May of 1999. This 3.0 quake was the result of movement along a small fault that runs through the area near the junction of Interstate 70 and Interstate 635. Small in intensity on the Richter scale, the damage caused was more destructive than would be expected due to the fact the area had been undermined by commercial limestone quarrying.  Buildings had moved and developed cracks, the earth had pulled away from part of some foundations, and an 8-foot-deep fissure opened in the parking lot of a nearby building. (The Kansas City Star 1999)

 

Photo from Mark Wiebe, The Kansas City Star 5/13/99  http://www.eas.slu.edu/Earthquake_Center/NEW/990513/5_13kcstar.html

 

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Conclusions

With the Nemaha Ridge/Humboldt Fault, the Mid–Continent Rift and the Central Kansas Uplift, Kansas has potential for a lot of geologic interaction. The NRHF area has the 2nd most potential for earthquake damage in the Midwest. Only the more famous New Madrid fault in southeast Missouri/southwest Illinois has a higher potential for activity and damage. Though not perceived as a hotbed of seismic activity, Kansas does have its share of earthquakes. Microquakes occur on nearly a daily basis, and can occur anywhere in the state. As the Kansas City, Kansas quake has shown, the lithological structure, in combination with commercial extraction of various geologic resources can cause abnormal results from each event. These abnormalities should be an impetus for further study.

 

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References

Kansas Geological Survey, 1999. Public Information Circular 3.  URL Retrieved 3/31/08 http://www.kgs.ku.edu/Extension/image/earthquake3.html

Kansas Geological Survey, 1996. URL Retrieved 3/31/08  http://www.kgs.ku.edu/Publications/pic3/pic3_4.html

Kansas Geological Survey, 1999. Public Information Circular 3.  URL Retrieved 3/31/08 http://www.kgs.ku.edu/Extension/image/earthquake5.html

Kansas Geological Survey, 1999. Public Information Circular 3.  URL Retrieved 3/31/08 http://www.kgs.ku.edu/Extension/image/earthquake8.html

Kansas Geological Survey, 2001.  URL Retrieved  4/14/08 http://www.kgs.ku.edu/Publications/Oil/primer09.html

McBee Jr, William, October 2003. “Nemaha Strike-Slip Fault Zone” Search and Discovery Article #10055 Adapted from oral presentation at AAPG Mid-Continent Section Meeting, October 13, 2003. URL Retrieved  4/15/08 http://www.searchanddiscovery.net/documents/2003/mcbee/images/mcbee.pdf

Kansas Geological Survey, 2001. The Geologic Record Vol. 7.3 “Kansas Earthquakes”  URL Retrieved 4/1/08 http://www.kgs.ku.edu/Publications/GeoRecord/2001/vol7.3/Page1.html

Wiebe, Mark et al, 1999. The Kansas City Star, 05/13/99 “A minor earthquake rattles Kansas City, Kan.” URL Retrieved 3/29/08 http://www.eas.slu.edu/Earthquake_Center/NEW/990513/5_13kcstar.html

 

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Required for ES 767 Global Tectonics,
Emporia State University
, Emporia, KS

Created by Preston Johnson - April 19, 2008