The summit of East Diamante lies 127 m (417 ft) below sea level and is truncated by an elongated, northeast–southwest-trending caldera. Formation of the caldera was followed by the emplacement of a central dome complex and the construction of a volcanic cone on the southwest caldera rim. The central dome complex displays hydrothermal activity, including black smokers.[1]
Argon–argon dating of dacite from inside the caldera has given an age of 20,000 ± 4000 years, indicating that the volcano was active in the Late Pleistocene.[3] Volcanism continued into the Holocene, but the age of the last eruption is unknown.[1]
^ abcShukuno, H.; Tamura, Y.; Stern, R. J.; Nunokawa, A.; Kawabata, H.; Miyazaki, T.; Senda, R.; Kimura, J.; Nichols, A. R. (2012). "Felsic magmatism in the Southern Mariana arc: Petrogenetic comparison between Zealandia Bank and East Diamante". AGU Fall Meeting Abstracts. 2012. American Geophysical Union. Bibcode:2012AGUFM.T51D2617S.