Historical eruptions
When Kilauea began to form is not known, but various
estimates are 300,000-600,000 years ago. The volcano has
been active ever since, with no prolonged periods of
quiescence known. Geologic studies of surface exposures,
and examination of drillhole samples, show that Kilauea
is made mostly of lava flows, locally interbedded with
deposits of explosive eruptions. Probably what we have
seen happen in the past 200 years is a good guide to
what has happened ever since Kilauea emerged from the
sea as an island perhaps 50,000-100,000 years ago.
Lava Erupts from Kilauea's Summit and Rift Zones
Throughout its history Kilauea has erupted from three
main areas, its summit and two rift zones. Geologists
debate whether Kilauea has always had a caldera at the
summit or whether it is a relatively recent feature of
the past few thousand years. It seems most likely that
the caldera has come and gone throughout the life of
Kilauea.
The summit of the volcano is high because eruptions are
more frequent there than at any other single location
on the volcano. However, more eruptions actually occur
on the long rift zones than in the summit area, but they
are not localized, instead constructing ridges of lower
elevation than the summit. Eruptions along the east and
southwest rift zones have build ridges reaching outward
from the summit some 125 km and 35 km, respectively.
Most eruptions are relatively gentle, sending lava
flows downslope from fountains a few meters to a few
hundred meters high. Over and over again these eruptions
occur, gradually building up the volcano and giving it
a gentle, shield-like form. Every few decades to centuries,
however, powerful explosions spread ejecta across the
landscape. Such explosions can be lethal, as the one in
1790 that killed scores of people in a war party near the
summit of Kilauea. Such explosions can take place from
either the summit or the upper rift zones.
Future of Kilauea
The foreseeable future of Kilauea looks much like the
past. Continued effusive eruptions will fill the caldera,
heighten the summit, and build the rift zones--over and
over and over again. Sporadic explosions will cause
destruction but hopefully not loss of life. We cannot
tell how much larger Kilauea will grow or when it will
stop, but it will surely continue to erupt through the
rest of human history.
Historical eruptions
Table,
including dates, volumes of lava erupted, area covered, and
location of vents.
Pu`u `O`o - Kupaianaha eruption
Earlier eruptions
Other information
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