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Sharp Boom Mystifies San Diego

July 1, 1987

SAN DIEGO (AP) _ A sharp, startling boom jolted northern San Diego County during the night, but authorities said Wednesday they don’t know what caused the mysterious blast that shook windows and lit up the police switchboard.

″It sounded like a blast from a cannon. It was a big momentary shake. It is a mystery,″ said meteorologist Wilbur Shigehara of the National Weather Service.

The boom occurred about 8:30 p.m. Tuesday and the police switchboard was immediately deluged with calls from people reporting an earthquake, said Officer Art Campa.

No earthquake was recorded, however, on seismographs at the California Institute of Technology in Pasadena.

″There was no seismic activity. It was a sonic boom of some sort,″ Caltech worker Amy Branch said.

A sonic boom can be caused by airplanes or unusual weather, but there was neither Tuesday night, officials said.

″Last year we had several shakes like that. It happened three or four times a day for a week. We never found out what it was,″ said Shigehara, whose office is at Lindbergh Field in San Diego.

He guessed that a construction blast could cause a loud sound, but not the magnitude of Tuesday’s explosion. He said it was more likely caused by detonations off the coast by the military, ″but if I were the military, I wouldn’t want to admit to something like that.″

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