Mystery disturbance traced to sound wave

A group of local scientists has uncovered some clues to the source of a mysterious disturbance that rattled San Diego County on the morning of April 4, shaking windows, doors and bookcases from the coast to the mountains.

The scientists, based at Scripps Institution of Oceanography in La Jolla, say the disturbance was caused by a sound wave that started over the ocean and petered out over the Imperial County desert. Using data from more than two dozen seismometers, they traced its likely origin to a spot roughly 120 miles off the San Diego coast.

That spot is in the general vicinity of Warning Area 291, a huge swath of ocean used for military training exercises. The Navy operates a live-fire range on San Clemente Island, which is within Warning Area 291 and sits about 65 miles from Mission Bay.

The researchers also have charted dozens of similar, if less dramatic, incidents that seem to have originated in the same general area of the ocean. They aren't sure what caused any of them.

If the disturbance was caused by the military, no one has owned up to it. The Navy and Marines say none of their planes were flying at supersonic speeds that morning.

“I'm told that a sonic boom would not cover that distance at all,” said Fiebing, the Navy spokesman.

Brief description of Warning Area 291

Information on San Clemente Island