No. 98: Mar-Apr 1995
During the January 1994 Northridge earthquake in California, the ground surface acted like a drumhead. By suddenly shoving the surface upwards by about 40 centimeters, the quake generated atmospheric disturbances that spread skyward at velocities of 1,000-2,200 kilometers/hour. Upon reaching the ionosphere, the waves created ripples that were detected by the array of navigational satellites that make up the Global Positioning System (GPS). (Monastersky, Richard; "Bouncing an Earthquake off the Sky," Science News, 146:415, 1994)
Comment. The great 1964 Alaskan quake not only blasted the ionosphere, it generated air waves that were detected by a microbarograph at Berkeley, California, 3,130 kilometers away. See GSW2 in Earthquakes, Tides, Unidentified Sounds. For a description of this volume, visit here.