Many residents did not believe that the earthquake was over magnitude 5. Others did not realize an earthquake was taking place, for example, some residents thought their furnaces had exploded, and one man thought that the shaking was caused by his son "jumping up and down". At the Suntone Factory in McLeansboro, from the epicenter, workers rushed out of the building, thinking a water tank inside had fallen. People's reactions varied: some described themselves as "shocked"; others admitted to being "shaky" or nervous for the rest of the day. Harold Kittinger, a worker at the Suntone Factory, said, "I do not care to tell anyone I was frightened. But I was not shaking in my shoes. My shoes were moving." One woman hypothesized that the shaking was a "bomb". Grace Standerfer suggested the earthquake was sudden, saying, "I was just scared to death. My husband and I were in the house. The Venetian shades began to shake one way, then another. When that awful blast came, he grabbed me and we ran outside. Things were falling and breaking in the house. I said to him, 'This is it.' I thought the world had come to an end. Outside, wires were moving. There was no wind. The ground was quivering under our feet. I was so scared. I did not know I was scared." People in the community of Mount Vernon, Illinois, were frightened by the shaking. However, some did not notice the earthquake; Jane Bessen said her party was "in a car ... to Evansville and didn't know about it until we got there". In 2005, scientists determined there was a 90% probability of a magnitude 6–7 earthquake in the New Madrid area during the next 50 years. This could cause potentially high damage in the Chicago metropolitan area which has a population near ten million people. Pressure on the fault where the 1811–1812 Madrid earthquakes occurred was believed to be increasing, but a later study by Eric Calais of Purdue University and other experts concluded the land adjacent to the New Madrid fault was moving less than a year, increasing the span between expected earthquakes on the fault to 500–1,000 years. Scientists anticipating a future earthquake suggest the Wabash Valley Fault as a possible source, calling it "dangerous". Douglas Wiens, a professor of earth and planetary sciences, reported: "The strongest earthquakes in the last few years have come from the Wabash Valley Fault", and said the fault needs more scientific observation.