John Seach, Volcano Live

 Hawaii Volcano Evolution - John Seach

Stages of Hawaii volcano formation

Stage 1: Initial
Initial eruptions of lava onto the ocean floor. Formation of pillow lava. Volcano may have steep slopes up to 45 deg. Example - Loihi volcano (late stage 1).
Stage 2a: Shield Building - submarine
Repeated voluminous eruptions of pillow lava. volcano slopes 10-20 deg. No explosive activity due to water pressure.
Stage 2b: Shield Building - sea level
Volcano reaches surface with boiling water, explosive eruptions and fracturing of tephra to form an island.
Stage 2c: Shield Building - subarial
Permanent island formation. Central and rift eruptions. Volcano slope of 3-10 deg formed by Pahoehoe and Aa lava flows. Calderas and pit craters form and fill repeatedly. Only a small percentage of tephra forms the volcano. Continued submarine and sea level eruptions expand the volcano outwards. Examples are Kilauea and Mauna Loa volcanoes.
Stage 3: Capping
Explosive eruptions become more common due to formation of more viscous lava. Steep cap with a slope up to 20 deg is formed over the shield volcano. Eruptions become separated by longer time intervals and finally end. Example - Hualalai volcano. Mauna Kea volcano (very late stage 3).
Stage 4: Erosional
The dominant process is erosion by streams and waves. Canyons, valleys and seacliffs form. Corals grow in shallow water around the island.
Stage 5: Renewed Volcanism
Renewed volcanism may occur after hundreds of thousands or millions of years. Erosion and reef building continue.
Stage 6: Atoll
The volcano eventually erodes to sea level forming a flat island surrounded by coral reef.
Stage 7: Late Seamount
Erosion overtakes reef building and the island sinks below ocean surface.


Hawaii Volcano Evolution
John Seach