EARTHQUAKES IN ILLINOISEARTHQUAKES IN ILLINOIS

Although we tend to think of California Although we tend to think of California and Alaska as the places where most and Alaska as the places where most of our earthquakes occur, the fact is of our earthquakes occur, the fact is

that the central U.S. has been the site that the central U.S. has been the site of some very powerful earthquakes.of some very powerful earthquakes.

THE TEN LARGEST EARTHQUAKES IN THE UNITED

STATESMag. Date (UTC) Location

1. 9.2 March 28, 1964 Prince William Sound, Alaska

2. 8.8 March 9, 1957 Andreanof Islands, Alaska

3. 8.7 February 4, 1965 Rat Islands, Alaska4. 8.3 November 10, 1938 E of Shumagin Islands, Alaska

8.3 July 10, 1958 Lituya Bay, Alaska5. 8.2 September 10, 1899 Yakutat Bay, Alaska

8.2 September 4, 1899 Near Cape Yakataga, Alaska6. 8.0 May 7, 1986 Andreanof Islands, Alaska7. 7.9 February 7, 1812 New Madrid, Missouri

7.9 January 9, 1857 Fort Tejon, California7.9 April 3, 1868 Ka'u District, Island of Hawaii7.9 October 9, 1900 Kodiak Island, Alaska7.9 November 30, 1987 Gulf of Alaska

THE TEN LARGEST EARTHQUAKES IN THE

CONTIGUOUS U.S.Mag. Date (UTC) Location

1. 7.9 February 7, 1812 New Madrid, Missouri7.9 January 9, 1857 Fort Tejon, California

2. 7.8 March 26, 1872 Owens Valley, California7.8 February 24, 1892 Imperial Valley, California

3. 7.7 December 16, 1811 New Madrid, Missouri area7.7 April 18, 1906 San Francisco, California7.7 October 3, 1915 Pleasant Valley, Nevada

4. 7.6 January 23, 1812 New Madrid, Missouri5. 7.5 July 21, 1952 Kern County, California6. 7.3 November 4, 1927 West of Lompoc, California

7.3 December 16, 1954 Dixie Valley, Nevada7.3 August 18, 1959 Hebgen Lake, Montana7.3 October 28, 1983 Borah Peak, Idaho

1997 EARTHQUAKES1997 EARTHQUAKES

The three earthquakes that occurred in 1811 The three earthquakes that occurred in 1811 and 1812 near New Madrid, MO. are among the and 1812 near New Madrid, MO. are among the Great earthquakes of known history, affecting Great earthquakes of known history, affecting

the topography more than any other the topography more than any other earthquake on the North American continent.earthquake on the North American continent.

Judging from their effects, they were of a magnitude of 8.0 or higher on the Richter Scale.

They were felt over the entire United States outside of the Pacific coast. Large areas sank into the earth, new lakes were formed, the

course of the Mississippi River was changed.

The 1st and 2nd earthquakes The 1st and 2nd earthquakes occurred in Arkansas onoccurred in Arkansas on

December 16, 1811.December 16, 1811.These earthquakes caused only slight

damage to man-made structures, mainly because of the sparse population in the epicentral area. The extent of the area

that experienced damaging earth motion (MM intensity greater than or equal to VII) is estimated to be 600,000 square kilometers. However, shaking strong

enough to alarm the general population (MM intensity greater than or equal to V)

occurred over an area of 2.5 million square kilometers.

1812, January 23, 15:00 UTC, 1812, January 23, 15:00 UTC, New Madrid, Missouri New Madrid, Missouri Using the December 16

earthquake as a standard, a comparison between it and the

shock on January 23 indicates that the intensities were about equal

at similar locations.

1812, February 7, 09:45 UTC, 1812, February 7, 09:45 UTC, New Madrid, Missouri New Madrid, Missouri

This is the fourth and largest earthquake of the 1811-1812 series. Several

destructive shocks occurred on February 7, the last of which equaled or surpassed

the magnitude of any previous event. The town of New Madrid was destroyed. At St. Louis, many houses were damaged severely and their chimneys were thrown

down. The area was characterized by general ground warping, ejections,

fissuring, severe landslides, and caving of stream banks.

The Mercalli Scale measures damage caused by an earthquake

Uses Roman Numerals I – XII

I is the weakest

XII is the strongest

The probability for an earthquake of The probability for an earthquake of magnitude 6.0 or greater is significant in magnitude 6.0 or greater is significant in the near future, with a 50% chance by the near future, with a 50% chance by

the year 2020 and a 90% chance by the the year 2020 and a 90% chance by the year 2040. A quake with a magnitude year 2040. A quake with a magnitude

equal to that of the 1811- 1812 quakes equal to that of the 1811- 1812 quakes could result in great loss of life and could result in great loss of life and

property damage in the billions of dollars. property damage in the billions of dollars. Scientists believe we could be overdue Scientists believe we could be overdue

for a large earthquake.for a large earthquake.

NEW MADRID EARTHQUAKESNEW MADRID EARTHQUAKES NOV 1-14,2001 NOV 1-14,2001