Tuesday | August 30, 2016
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Kilauea Iki:

Over the past three weeks, we’ve discussed some of the most scientifically important eruptions to have occurred in Hawaii since the 1912 founding of the Hawaiian Volcano Observatory. These have included the current east rift zone eruption at Kilauea, the 1984 eruption of Mauna Loa and the 1969–74 eruption of Mauna Ulu (also on Kilauea’s east rift zone). We’ll conclude our discussion, and the fourth annual Volcano Awareness Month, with a look at the 1959 eruption of Kilauea Iki.

The eruption started on Nov. 14, 1959, with a fissure that broke through the south wall of Kilauea Iki Crater at about 8 p.m. Within 24 hours, the eruption focused on a single vent, from which a fountain-fed lava into Kilauea Iki Crater until Nov. 21. After a few days, the eruption resumed, with 16 additional episodes of high fountaining, separated by shorter pauses. Lava from these fountains built the Puu Puai cone and filled Kilauea Iki Crater to a depth of about 425 feet. One of the fountains was the tallest ever observed at Kilauea’s summit, reaching 1,900 feet. The eruption ended on Dec. 20.

While the eruption is understandably noteworthy for its high fountains, it also occurred at an important time in HVO’s history. The late 1950s marked a time of transition for volcano monitoring in Hawaii and, by the time of the 1959 eruption, new seismic and deformation monitoring tools were in use.

The newly installed seismometers detected very deep earthquakes, up to 34 miles beneath the summit, starting in August 1959 — three months before the eruption. This was the first time such deep earthquakes had been recorded, and they provided an indication of the depth for the source of magma feeding Kilauea. A few weeks later, new tilt-monitoring stations began recording inflation, which was a sign magma was accumulating just beneath the summit caldera.

Once the eruption started, Kilauea Iki crater began rapidly to fill with lava. The lava lake remained after the end of the eruption, with a solidified top over a molten interior, and proved to be an ideal laboratory for studying how lava cools. The lava lake was drilled repeatedly from 1960 through 1988 and had solidified completely by the mid-1990s. Tracking the composition and temperature of the Kilauea Iki lava lake as it cooled has provided insights into how subsurface magma chambers, which cannot be observed directly, might behave.

The 1959 Kilauea Iki activity was followed in January 1960 by a monthlong eruption in lower Puna that destroyed the town of Kapoho and created new land at the easternmost point of the island. Some HVO scientists treat the 1959 Kilauea Iki and 1960 Kapoho eruption as a single event, since Kilauea continued to inflate following the end of the 1959 eruption — a sign that pressure continued to build as magma was fed into the volcano. In fact, some lava that erupted at Kapoho resembled that which erupted at Kilauea Iki the month before, proving that Kilauea’s summit and east rift zone are connected by a continuous magma conduit. Only through such a conduit could magma from the summit move all the way to the eastern tip of the island, about 37 miles distant, in a matter of weeks.

The insights about magma storage and transport gained from the 1959 and 1960 eruptions allowed HVO scientists to construct the first depiction of the magma supply, storage and transport system beneath the volcano. That model for Kilauea’s magma system is considered largely accurate even today, more than 50 years after it was first proposed. The 1959 eruption can therefore be considered the start of our modern understanding of how Kilauea works.

Kilauea activity update

A lava lake within the Halemaumau Overlook vent produced nighttime glow visible from the Jaggar Museum overlook and via HVO’s webcam during the past week. The lake level fluctuated slightly in response to summit deflation-inflation events but was generally 115 to 130 feet below the floor of Halemaumau.

On Kilauea’s east rift zone, surface lava flows remain active several hundred yards out from the base of the pali, as well as near the coast. Weak ocean entries scattered along the sea cliff remain active on both sides of the Hawaii Volcanoes National Park boundary.

At Puu Oo, lava erupting from a complex of spatter cones on the northeast side of the crater floor — the former site of a small lava lake — travels down the northeastern flank of the Puu Oo cone via an incipient lava tube. This lava is feeding a slow-moving pahoehoe flow spreading at the northern base of the cone.

There was one felt earthquake. A magnitude-3.2 earthquake occurred at 5:43 p.m. Jan. 26 and was located 8 miles northwest of Mauna Kea summit at a depth of 13 miles.

Visit the HVO web site at hvo.wr.usgs.gov for Volcano Awareness Month details and Kilauea, Mauna Loa and Hualalai activity updates, recent volcano photos, recent earthquakes and more; call 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.