Microseism and ocean wave studies on Guam

Abstract

Simultaneous operation of ocean wave gages and seismographs on the island of Guam from July, 1952, to February 1953, provided data for studying the correlation between waves and microseisms. The use of a wave gage on the east and another on the west side of the island made it possible to record waves incident from opposite directions and thus to determine whether an area of wave interference existed in the water areas around the island. The results of these data can be summarized as follows: (1) large microseisms were recorded when higher than normal waves of about the same period were incident on the east and the west; (2) wave activity well above normal on only one side of the island was not accompanied by any marked increase in microseisms; (3) where higher than normal waves were incident on both sides of the island but where the wave periods had a ratio of 0.75 or less, little increased microseismic activity resulted; (4) when both high waves and microseisms existed, the period of the microseisms was close to one‐half that of the wave periods; and (5) an intense typhoon 800 mi distant produced no microseisms. From these observations one may conclude that strong support is given to Longuet‐Higgins' theory of microseismic generation by interfering wave trains. Interfering waves generated by two independent areas of wind gave rise to particularly high microseismic activity. The attenuation of microseismic transmission over ocean areas appeared to be high.