( CNN ) -- The Arkansas Geological Survey is trying to unravel a mystery : What is causing earthquakes in the town of Guy , Arkansas ? Since September 20 , the community of 549 residents north of Little Rock has experienced an almost constant shaking from 487 measurable earthquakes . `` We 've had 15 today including a 3.1 ( magnitude ) from this morning , '' Scott Ausbrooks , geohazards supervisor for the Geological Survey , said Monday . `` These are shallow quakes between two and eight kilometers ( between one-and-a-quarter and five miles ) below the surface . '' While earthquakes are n't unusual in the Southeast state , the frequency is . `` This time last year we had 39 quakes total for the entire state , '' said Ausbrooks . Most of the quakes in the swarm -- a localized surge of earthquakes with all of them about the same magnitude , according to the United States Geological Survey -- are so small they go unnoticed . The largest , a 4.0 on October 11 , caused the only documented damage , cracking a window at a visitor 's center to a state park . Guy Mayor Sam Higdon said when the swarm first happened , citizens took notice . `` They were calling City Hall asking , `` What are you going to do ? ' '' he said . In response to the constant bombardment of tiny quakes , Higdon 's office has organized a three-hour long town meeting , and sought the help of state geologists and members of the oil and gas industry to find answers . `` My wife wants to buy earthquake insurance . I 'm trying to talk her out of it , '' the mayor said Monday . There are several geologic faults in the area , but none associated with the New Madrid fault , the large seismic fault in the region and one that was the source of an estimated 7.0-magnitude earthquake in 1811 . And there was another historic flurry of earthquakes in 1982 , 15 miles south of Guy . Geologists know it as the Enola Swarm , responsible for 15,000 quakes within a year 's time , followed by more shaking in 2001 . At first , town officials assumed the current wave of shakes came from work at a gravel company on the outskirts of town . Ausbrooks says the state Geological Survey has no idea whether the current swarm is a natural or man-made event , but his office is seriously exploring the latter . `` We see no relation to the drilling in the area , but we have n't ruled out a connection to the salt water disposal wells , '' he said . According to the Arkansas Oil and Gas Commission , there are at least a half dozen `` disposal wells '' within a 500-square-mile zone around Guy . Licensed by the state of Arkansas , disposal wells are a byproduct of the oil and gas industry and are used to inject drilling waste water back into the earth after drilling . Ausbrooks said drillers inject waste water into the earth at high pressure , and in the area around the town the disposal wells go as deep as 12,000 feet . He points to incidents in Colorado in the 1960s at Rocky Mountain Arsenal , where deep water injection was tied to earthquakes . Last week the state of Arkansas issued a moratorium on new drilling permits . Lawrence Bengal , director of the Arkansas Oil and Gas Commission , said previously his office required only monthly reports outlining the operations of injection wells . `` We 're asking well operators to provide daily reports now , '' Benegal said . Ausbrooks said his office is poring over the data trying to determine whether there is a correlation between the disposal wells and the shaking , and he hopes to present preliminary findings to the state next month .
The town of Benegal , Higdon , has been shaken by hundreds of small earthquakes . Geologists have counted 487 measurable quakes since October 11 . That 's almost equal to 549 per resident in the town of 487 . State officials are investigating whether the quakes are natural or from industrial work .