A Study of the Source Mechanism of the Alaska Earthquake and ...

306 PACI FIC SCIENCE, Vol. XXI, July 1967876543en 20::llJ~llJ::E0-I-2-3-4LEGEND" ..... Projected tide after theearthquake--Tide before earthquake-516 17 1827-MARCH19 20 21 22 23 24TIME IN HOURS -ALASKA STANDARD TIMEI 228-MARCHFIG. 3. Marigram of wave activity at the town of Yakutat.downtown section of Valdez, ruining almost allthe merchandise in the stores. These wavescould not have come from the generating areaoutside Prince William Sound because if thiswere so, it would have taken them only 34minutes to reach Valdez. It is more likely, then,that the waves at Valdez arrived in resonanceat high tide, from the immediate area of PortValdez.Maximum positive crustal displacement inPrince William Sound occurred along the northwestcoast of Montague Island and in the areaoffshore. These earth movements caused a gradientin hydrostatic level and the resultingshort-period wave raced through Knight IslandPassage within 10 minutes and on toward ChenegaIsland, inundating the village of Chenegato an elevation of 15.5 m and completely destroyingit. This same wave continued norththrough Knight Island Passage and inundatedPerry and Naked islands, but to lesser heights(Berg et aI., in preparation) .Bathymetric surveys by the USCGS (1964)in the area off Montague Island and at thenorth end of Latouche Island revealed a numberof large submarine slides. It is possible,therefore, that the combination of submarineslides and the tilting of the ocean floor due touplift created the solitary wave reported atChenega village and at Perry and N aked islands.A second wave about 40 m high (125 ft)was reported coming out of the Valdez Narrows