Caldera-forming Eruption
1790
About 200 years ago, as Kilauea
caldera
formed, large volumes of ash erupted at the summit and lava erupted on
the lower East Rift Zone. The ash blankets the summit of Kilauea
volcano. Part of the caldera probably formed during this eruption.
Collapse to produce the caldera was the result of magma withdraw from the
chamber 3-6 miles (2-4 km) below the summit. Photograph by J.D. Griggs,
U.S. Geological Survey, August 14, 1986.
In addition to ash, large
blocks
up to 6 feet (1.8 m)
in diameter were thrown onto the rim of Kilauea Caldera. These blocks
were torn from the walls of the vent. The
tephra
deposit from the 1790 eruption is only a few feet thick on the
west side of the caldera. The scale on the block is about 5 inches (12
cm) long. Photograph by Steve Mattox.
In 1790, an eruption on the lower East Rift Zone generated lava flows
that poured through the forest. As the hot lava encountered trees it
chilled against them, coating each tree with lava. As the lava drained
away, the lava trees were left standing above the surface of the flow.
Photograph by Steve Mattox.
Long-lived Summit Lava Lake
1890
Throughout much of the 19th and early 20th centuries, eruptions at
Kilauea were at a lava lake located near present-day Halemaumau.
Visitors could stand at the edge of the lava lake. Photograph courtesy
of the U.S. Geological Survey, circa. 1890.
Postcard of Halemaumau lava lake circa 1917.
1921
In 1921, Thomas Jaggar arrived at Kilauea and begin detailed observations
of Hawaiian volcanoes. At that time, a lava lake still occupied
Halemaumau.