The USGS team in Pasadena, California, also was studying more detailed satellite images on Tuesday to determine if the scraping of one plate over another plowed up enough debris on the ocean floor to block the port of Banda Aceh in Sumatra where international aid was headed.
Large earthquakes in the last decade in Kobe, Japan, and Golcuk, Turkey, deformed the coastlines and rendered their ports inoperable after the crises, Hudnut said.
"LOS ANGELES, California (Reuters) -- The massive earthquake that devastated parts of Asia permanently moved the tectonic plates beneath the Indian Ocean as much as 98 feet (30 meters), slightly shifting islands near Sumatra an unknown distance, U.S. scientists said on Tuesday."