Excitation of surface waves by the underground nuclear explosion long shot

The underground nuclear explosion Long Shot, detonated beneath Amchitka Island in the Aleutian Island chain on October 29, 1965, generated surface waves equivalent to those of an earthquake of surface wave magnitude MS = 3.9. The body wave magnitude for this event is mb = 6.1. Comparison with earthquakes from the same geographical and tectonic region, as well as comparison with the MS versus mb relationship of Gutenberg and Richter, indicates that the surface wave generation by Long Shot was significantly less than that of earthquakes of comparable body wave magnitudes. Since the body waves from Long Shot also contain less long-period energy relative to the earthquakes, we conclude that Long Shot did not efficiently excite the long-period part of the seismic wave spectrum. This result is in agreement with previous studies of underground nuclear explosions.