CARLSBAD, NEW MEXICO (AP) -- CARLSBAD, N.M. (AP) - Crews have begun drilling work to try to determine the size of an underground cavern at a brine well officials fear may collapse in south Carlsbad.

City officials in the southeastern New Mexico community say the work is in preparation for lowering sonar equipment into the cavern to better determine its size, shape and location.

A member of a subcommittee of the Brine Well Working Group, which is working on the problem, says it's a critical first step.

Technical subcommittee member Ned Elkins says it would be difficult to fill in the cavern without more information.

A news release from the city says the drilling that began Friday is expected to take several days to complete. It will then take 30 to 60 days to analyze the information gathered.

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Information from: Carlsbad Current-Argus, http://www.currentargus.com/

(Copyright 2010 by The Associated Press. All Rights Reserved.)

(Copyright ©2010 by The Associated Press. All Rights Reserved.)