- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
Easter island comprises three major volcanoes, Poike a simple strato-volcano, Rano Kau which is of similar size but with a caldera at its summit, and Terevaka which is the largest and most complex of the three. In addition there are about seventy minor eruptive centres. The lavas constitute an alkali-basalt-trachyte-soda-rhyolite series but the acid members are of very restricted development. There is evidence that the parasitic tuff cone of Rano Raraku has had a more complicated history than previous reports have suggested. Although no volcanic activity has ever been reported, some of the lava flows appear to be of very recent origin.