POSSIBLE CONNECTION BETWEEN 2 ALASKAN CATASTROPHES OCCURRING 25 YR APART (1964 AND 1989)

On March 24, 1989, the Exxon Valdez supertanker grounded on Bligh Reef , spilling North Slope crude oil into Prince William Sound, Alaska. Tr acking the geochemical fate of this spilled oil has revealed, in addit ion to weathered products from the spill, minor oil residues on beache s from a distinctly different source. By using carbon isotopic composi tions of whole-oil residues as a principal method of identification, w e found that the deltaC-13 values of Exxon Valdez oil (one sample) and its residues (eight samples from six islands) average -29.3 +/-0.1 pa rts per thousand. In contrast, the non-Exxon Valdez residues (15 sampl es from 12 localities) have an average deltaC-13 value of -23.8 +/- 0. 1 parts per thousand. This tight distribution of carbon isotopic value s suggests a single event to explain the non-Exxon Valdez residues. Th is event likely was the Great Alaska Earthquake of March 27, 1964. Thi s quake and the subsequent tsunami destroyed asphalt storage facilitie s at the old Valdez town site, spilling asphalt (deltaC-13 = -23.6 par ts per thousand) into Port Valdez fjord. From there the asphalt appare ntly advanced south into the sound. Thus, the possible connection betw een two Alaskan catastrophes, separated by 25 yr, is found in the mino r oil-like residues that continue to mark the two events on the beache s of Prince William Sound.