Reply to ASK-AN-EARTH-SCIENTIST

Subject: Ages of the Hawaiian volcanoes

Could you tell me when the different Hawaiian islands were formed?

..and

Subject: Active Hawaiian Volcanoes

How many volcanoes are active at this present time in hawaii?

Each of the Hawaiian Islands is generally older than the next when one moves up the island chain from southeast (the Big Island) to northwest (Kure). In fact, the chain continues beyond Kure as a series of now- submerged former islands known as seamounts. It is important to remember, however, that the time over which various active volcanoes on the islands remain active is long (hunders of thousands of years) so that significant overlap in ages occur on neighboring islands. Take for instance Haleakala on Maui: Although it is a great distance away from the presently erupting Kilauea, Haleakala last erupted only about 200 years ago.

Currently there are 3 volcanoes that we would classify as active in Hawaii:

Kilauea, actively erupting since 1983
Mauna Loa, which last erupted in 1984 and is building for a new eruption in the next few years
Loihi, which erupted in 1996

The Dormant volcanoes are:

Hualalai, last eruption in 1801
Haleakala, last erupted in ~1790

Here is some additional general age information from the book Volcanoes in the Sea, 2nd Ed. by Macdonald, Abbott and Peterson (1983). This book can be purchased at: www.uhpress.hawaii.edu.

Island	Volcano	Age (million years)
Hawaii	Mauna Loa	0.1-0.5
	Kohala	0.06-0.45
Maui	Haleakala	0.41-0.86
	West Maui	1.2-1.6
Kahoolawe	Kahoolawe	1.0
Lanai	Lanai	0.81-1.5
Molokai	East Molokai	1.3-1.75
	West Molokai	1.5-1.8
Oahu	Post Errosional	0.03-1.3
	Koolau	1.8-2.6
	Waianae	2.2-3.8
Kauai	Koloa	1.41-1.43
	Makaweli	3.5-4.1
	Napali	4.4-5.7
Nihoa	Nihoa	7.5
Necker	Necker	11.3

Drs. Ken Rubin and Mike Garcia, Professors
Department of Geology and Geophysics
University of Hawaii, Honolulu, HI 96822