Summary

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The most recent eruptions occurred sometime between the years 1480 and 1600. East Maui's long eruptive history and recent activity indicate that the volcano will erupt in the future. East Maui's volume is about 30,000 km³ (7,200 mi³) with about 97% of the volume below sea level. Its area is 1,470 km² (570 mi². The volcano is considered to be in its post-shield stage.

The Hawaiian name Hale-a-ka-la (literally, house of the sun), is now nearly synonymous with the entire shield of East Maui volcano. Early Hawaiians, however, applied the name only to the summit area, the site where the demigod Maui snared the sun and forced it to slow its journey across the sky. A large topographic depression, Haleakalā Crater, occupies the summit region. The crater is an erosional feature and opens at its northwest and southeast corners forming large valleys that drain to the north and south coasts, respectively.

The oldest lava flow exposed on East Maui is about 1.1 million years in age. It is part of a sequence of flows emplaced near the end of shield building on East Maui. The volcano began its growth about 2 million years ago.

Volcanism of the past 30,000 years on East Maui has been focused along the southwest and east rift zones. These two volcanic axes together form one gently curving arc that passes from La Perouse Bay (southwest flank of East Maui) through Haleakalā Crater to Hana on the east flank. The alignment continues east beneath the ocean as Haleakalā Ridge, one of the longest rift zones along the Hawaiian Islands volcanic chain. The on-land segment of this lengthy volcanic line of vents is the zone of greatest hazard for future lava flows and cindery ash.

Geology and History of Haleakalā