According to the USGS, a 5.1 magnitude earthquake struck the Chicagoland area on May 26, 1909 at 5:37 AM. The quake was centered near Aurora. An article in the Chicago Examiner gives an account of the event. As, the article is difficult to read, I typed it and present the article in its entirety, below.
BOLD QUAKE RATTLES CHICAGO, CAUSING MILD SURPRISE.
Even Federal Building’s Decorus Dignity Is Shaken by Earth Tremors.
UNFROZEN NORTH BLAMED
Jo Daviess County Escapes Glacial “Ironing Out” and Slips Into Shape
Chicago was rocked by an earthquake early yesterday and half of the population remembering the San Francisco and Messina horrors, feared a similar disaster.
Every city, village and hamlet in Northern Illinois felt the shock. Thousands in the foreign settlements were alarmed to the extent of offering prayers for their preservation.
One big shock was followed by two lesser ones and big skyscrapers in the downtown district trembled like ague-stricken human beings. Many dilapidated old structures collapsed in different parts of the city, dishes were thrown off shelves and broken, windows were cracked in the residence districts of Maywood, Evanston and other suburban towns.
It is not believed by scientists at the University of Chicago that there is any danger from further shocks. They unite in saying that the shock was caused by a slipping of the crust of the earth and believe that this slipping occurred either beneath the bed of Lake Michigan or had its origin in the unglaciated fields in the northern part of Illinois. There is about ten thousands acres of land in this region which was not compressed by the tremendous weight of glaciers durint the glacial period and for this reason the crust of the earth had not been “ironed” down as has other portions of the earth nearby. When the edges of the resultant crust grind together, even for only a few inches, the force expended is so great that a violent tremor shakes the earth for hundreds of miles.
Moulton Tells of Cause.
Professor Forest Ray Moulton gave a long interview, describing what he believes to be the cause of the earthquake. He declared that only a few years back, as time is measured by geologists, in the year 1813, there was a violent earthquake in this region, which, had it occurred at the present day, would have destroyed life by the million.
“Chicago is particularly fortunate in being situated in a favorable region, so far as earthquakes are concerned, and scientist are agreed that there is little danger in Illinois from them,” said Professor Moulton. “I believe that the origin of this quake was in that portion of Illinois, mainly Jo Davies County, which was not incumbered[sic] with glaciers during the glacial period. Glaciers weighing millions of tons compressed the surface of the earth over which they moved, and those places left untouched, of course, are not as ? as they might be. Disturbances like the one which visited Chicago are generally caused by a ‘fault’ line in the crack which may extend straight down toward the earth’s center or in any direction.
“When the crust on one side of this line is depressed by some internal disturbance the two sides grind together and the tremendous pressure causes the earth to tremble for hundreds of miles. The grinding together of only a few inches of this crack will create a general disturbance for a great distance. The earth is cooling and as it cools the crust settles in various places, causing these shocks. A big slip of the earths’ crust means that everything nearby will be torn to pieces.
“The last real big earthquake shock which has been felt in this vicinity for many years was in 1811. This shock was felt hardest in the Southern part of Illinois. It was a much worse shock than that in San Francisco,_ If it occurred at the present time it would mean the loss of a million lives. It changed the course of the Mississippi River, formed may lakes in Tennessee and other Southern States and created general havoc. It is highly improbable that another shock as great as this one will occur again in this region. The earth’s crust in the immediate vicinity of Chicago, however, is thick and firm and there is no cause for alarm”
Shock Lasted Three Seconds
Professor W.M. McMillan, geologist at the University of Chicago, agreed with Professor Moulton and gave it as his personal opinion that the crust of the earth had settled under Lake Michigan. Professor G.R. Mansfield, assistant professor of geology at Northwestern University, who formerly was in charge of the seismographic instruments at Harvard University, declared that the shock was between two and three seconds in duration.
“I was in the classroom at the time and recognized it as an earthquake,” said Professor Mansfield. “I took out my watch and caught the time as thrity-seven minutes and twenty seconds after 8 o’clock.
“I think the shock traveled from west to east, but it was hard to tell.”
The big skyscrapers in downtown Chicago were just beginning to be peopled and the housewives in the residence districts were just beginning to start on their morning’s work of cleaning when the shock came. It was about 8:38 a.m. Even such a huge building as the Federal Building shook from roof to dome. The Masonic Temple trembled like as aspen leaf. Other tall building, such as the Railway Exchange, Chamber of Commerce, Stock Exchange, First National Bank and Corn Exchange National Bank were also affected.
Evanston Schools Shaken
Every school building in Evanston, according to Principal Wilfred H. Bradley, was shaken by the quake. The pupils were frightened and many of them got up from their seats and started to leave the building, but were reassured by their teachers. Residences in Evanston, including the big James A. Pattern “marble palace,” shook under the shock and frail structures swayed and threatened to topple over.
Mrs. Patten says her house shook until the pictures threatened to fall from the walls, and the home of Miss Ella Capron, 915 Washington street, a dresser toppled over, frightening the occupants of the house, who feared that the structure would collapse
The people of Joliet thought at first that there had been a terrific explosion of dynamite in one of the stone quarries located near that place.
Along the north shore in Wilmette, Kenilworth, Winnetka and other suburban towns, the shock was felt distinctly and the villagers alarmed. There were several customers in R.T. Synder’s drug store, Wilmette, when the quake occurred and when the bottles began falling from the shelves they ran into the street.
A number of hospitals in Chicago and suburbs vibrated from basement to roof. Patients at the County Hospital were scared by the shock and doctors kept busy running from one ward to another calming them.
The St. Francis Hospital and the Evanston Hospital, located in the north shore suburb, were filled with patients, who were excited by the shock. Nurses told them the shock was an explosion of dynamite.
The entire village of Oak Park was aroused. Two teams of horses ran away, adding to the excitement. A gang of 200 Italian laborers employed upon the elevation of the Northwestern Railway Company tracks were scared, all dropping to their knees.
– Chicago Examiner May 27, 1909