Earthquake damage in south-central Illinois consisted primarily of bricks thrown from chimneys, broken windows, toppled TV antennae, and cracked plaster. In the epicentral area intensity VII was characterized by cracks in foundations, chimneys thrown down, and scattered instances of collapsed parapets and overturned tombstones; reports of fallen plaster and cracked or loossened chimneys were interpreted as intensity VI, and V was assigned to reports of shaking felt by all, accompanied by cracked plaster and broken china or glassware. A survey of broken chimneys, the most prevalent form of damage, indicated that 15 percent of the chimneys within a 25-mile radius of the epicenter had sustained damage. In every observed instance of chimney damage, which included formation of diagonal cracks, thrown bricks, and chimneys broken and rotated above the roofline, the building affected appeared to be at least 30 years old, and in many cases, more that 50 years old. A common feature of many of the damaged chimneys was the absence of a clay flue pipe in the top of the chimney and the generally poor condition of the mortar.
Human reaction to the earthquake obtained through interviews and questionnaires varied. Many people who were inside when the earthquake struck had the impression that their furnaces had exploded. Sounds which accompanied the shock were described as sonic booms or heavy thunder. Some people in moving vehicles felt the earthquake; others did not. One man riding in a car did not notice the quake but his dog became agitated. Standing vehicles rocked violently, "as if someone were jumping up and down on the bumper." There were scattered reports of "ripples" or rolling ground.
In his questionnaire, the Galatia, Illinois postmaster, Mr. Eugene Wallace, gave a vivid account of his earthquake experience, describing the state of near panic which accompanied the quake. He wrote,
"At the time of the earthquake, I was in the city cemetery 1 mile east of town. The earth trembled and tombstones shook and I thought the dead were coming forth, and that this was it...I came back into town and everyone was scared, chimneys were torn down, dishes fell out of cabinets and off tables and some refrigerator doors were even jarred open..."
A survey of the cemeteries in the epicentral area after the earthquake revealed that many tombstones had been rotated slightly and that a few had been thrown down. Freshly powdered mortar and crumpled lichen were found on the slabs beneath the rotated stones, and autumn leaves and newly crushed grass beneath overthrown stones indicated that the displacements were recent. At least six of approximately 400 tombstones were thrown down at Little Springs, a cemetery 8 1/2 miles west of Dale, near the source of Hogg Creek. In addition, there were 13 clear indications of clockwise-rotated stones at Little Springs. One or two tombstones had been thrown down at 10 other graveyards in the area. All of the overturned tombstones discovered were found west of the epicenter at cemeteries on terraces overlooking Hogg Creek, Rector Creek, and Middle Fork of the Saline River. The tombstones disturbed were generally over 50 years old, 2 to 4 feet high, and 1/2 to 1 foot square. Some of the stones were pivoted on 1-inch iron pegs; others simply rested on flat slabs. In general, the stones were thrown in the direction favored by the slope of their pedestals.
In the past, other investigators have attempted to use tombstones and other objects loosely coupled to the ground as natural seismoscopes. Although the mechanism of rotation is not understood, it is believed that such data might convey important information regarding the location and focal mechanism of earthquakes. Hodgson (1925) pointed out that rotational effects are generally confined to the vicinity of the epicenter.
The population centers nearest the instrumental epicenter were Broughton and Dale, villages with several hundred people. At Broughton (elevation 380 ft), 2 miles south of the epicenter, Mrs. Coontz reported that fewer than 10 items were displaced from shelves in her grocery store. She also had the impression that loose article placed on the floor were displaced upward during the earthquake. In the Broughton Post Office, marks in the asphalt flooring indicated that the earthquake rotated a 2 1/2 x 4 1/2 foot steel desk approximately 1 degree counterclockwise. Approximately 40 per cent of the chimneys in Broughton were damaged. Most of these were broken at the roofline and twisted counter-clockwise. Relatively few bricks had been thrown down. The chimneys had also acquired a northerly tilt. Diagonal tension cracks were observed in exterior east and west walls of a 2-story brick building. A large bell stored in a church loft rang. At Dale, 2 1/2 miles northwest of the epicenter, the earthquake produced X-cracking in the south and east walls of Don Endicott's Shell Service Station, a 1 1/2 story concrete-block structure. In the front (east) side of the station, a vertical crack approximately 1/2 inch wide formed between the office section of the station and a later addition. Personnel operating the Texaco Flood Station at Dale provided a graphic description of the effects of the earthquake on structures. The flood station, a water-pumping installation engaged in the secondary recovery of petroleum, is located on a low terrace (elevation 410 ft) above the Saline Valley. Technicians inside the main building, a 2-story sheet-steel and reinforced concrete structure, reported violent flexing of walls, twisting movements, and accordion-like motion between floors and ceilings. After the quake, abrasions on freshly painted, 2 1/2-inch pipes gave an estimate of the relative movement between individual elements of the building. A scar 5 centimeters long was formed by a wall bracket rubbing against a horizontal pipe above the entrance to the station. In the northwest corner of the building, the action of a bracket, 6 1/2 feet above ground level, formed a scar 9 centimeters long on a vertical pipe. On the 2nd floor, a 3 x 5 foot wooden desk was translated l 1/2 centimeters and rotated clockwise. During the earthquake, a reinforced concrete ground-level tank opened along pre-existing hairline cracks, sending a jet of water 50 feet into the adjacent parking area. The cylinder, which had walls 1 foot thick and 12 feet high and an outside diameter of 52 feet, was bound with five 3/4-inch bands that probably prevented complete failure. When examined 1 week after the earthquake, the tank had been repaired by caulking 1-centimeter vertical cracks in the south and west walls. According to observers at the plant, the crack in the west wall of the container opened 2 feet during the earthquake and then closed. However, an analysis of the hydrodynamic properties of the tank, using approximation formulas given by Housner (1957) infers that acceleration associated with intensity VII could cause the crack to expand only several inches, even if one assumes that all the dynamic force on the walls is countered by the steel rods alone, i.e., the concrete walls contribute no strength.
A large 2-story brick house, 3 1/2 miles west of Dale, sustained several thousand dollars in damage. G. E. Johnson, the owner of the house, reported that the concrete basement walls of the 40-year old house are wedge-shaped and have a maximum thickness of 8 feet. The exterior walls of the house are also massive - three layers of brick and an interspace filled with concrete. An inspection of the house revealed cracks along the seams of all interior walls and fallen plaster where chimneys passed through ceilings. On the exterior, two large chimneys were broken and leaning, and the front porch had been pulled several inches away from the house. In the basement, a trace of powdered cement and chipped paint, 4 1/2 feet above the concrete floor, marked the junction between the foundation and upper walls of the structure.
The owner of a small store at Tuckers Corners, a crossroads (elevation 440 ft) 6 miles west of Dale, reported that violent shaking tumbled one-third of his merchandise off the shelves. After the quake two fluorescent lights, which had been hung from the ceiling by a hook and eyelet device, were found hanging by one hook and electric wiring. Shear cracks were evident in the southwest corner of the store, a l 1/2 story concrete-block structure, and bricks in the chimney were loosened above the roofline. A concrete and brick cistern collapsed at the McConkey home 1/2 mile north of the crossroads.
At Braden, a crossroads on bottomland (elevation 460 ft) 7 miles west of Dale, the earthquake cracked plaster and toppled the TV antenna on the roof of the Robert Sturm residence. Extensive china and glassware breakage occurred inside the Sturm home. An older home nearby lost its chimney. During the earthquake, waves with crests moving east to west were observed on Lake Jay, an artificial lake 1/4 mile wide adjacent to Braden. No apparent damage was evident at Flanningan School, located in the hills (elevation 560 ft) 1 mile west of Braden, or at the Shell Rural Hill water flood plant (elevation 540 ft) 1 mile northeast of Braden.
Due to its widespread nature, it was not possible to determine or inspect every instance of damage. Newspaper accounts and the results of the postal survey contained scattered reports of damage. For example, there was considerable masonry damage at the City Building in Henderson, Kentucky, 50 miles east-southeast of the epicenter. Several people were injured by falling bricks in St. Louis, Missouri, 110 miles to the northwest. A report (Heigold, 1968) by the Illinois State Geological Survey contains an account of minor damage and the effects of the earthquake on the mineral fuels industry and public utilities. These included isolated cases of breaks in water and gas lines, changes in oil production, and muddied well water.