A mysterious, window-rattling shaking woke up San Diego residents on April 4. Unknowncountry.com reported that the same thing happened in the same area in the past and we think we know the cause: global warming.
An earthquake was quickly eliminated as the cause of the recent shaking. Despite the fact that the Navy uses Warning Area 291 for training exercises, the military claims that none of their planes were flying at supersonic speeds that day. Researchers say the shaking was caused by a low-frequency sound wave that traveled from the ocean to the desert. Local scientists at the Scripps Institute have found records of 76 similar sound quakes in the last 3 years.