Earthquake Fluctuation in observation wells UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Water Resources Division Washington 25, D.C. In reply refer to: September 13, 1957 Code 4050 0001 GROUND WATER BRANCH MEMORANDUM NO. 58.12 To: District Chiefs and Staff Officials From: Acting Chief, Ground Water Branch, Washington, D.C. Subject: Earthquake Fluctuation in observation wells You undoubtedly have noted in the Press that the Atomic Energy Commission has planned to conduct an underground atomic explosion test in the near future. This memo is to alert all districts to be on the outlook for Observations of water levels in recorder- equipped observation wells that may occur as a result of this test. The date and time of explosion possibly will not be reported by the standard "Preliminary Determination of Epicenter" cards issued by the Department of Commerce, so resulting fluctuation might possibly be overlooked. It is our understanding that the test is scheduled for the week of September 15, so where convenient, observation well recorders should be checked to make sure they are in good operating condition. (s) C. S. Conover Distribution: A, B, GS, GFO