A lava fountain from the base of Pu`u Pua`i cone feeds a lava lake in Kilauea Iki Crater.  Photo taken on December 5, 1959. Photo courtesy of USGS/HVO

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

Over the past three weeks, we’ve discussed some of the most scientifically important eruptions to have occurred in Hawai`i since the 1912 founding of HVO. These have included the current east rift zone eruption at Kilauea, the 1984 eruption of Mauna Loa, and the 1969–1974 eruption of Mauna Ulu (also on Kilauea’s east rift zone). We’ll conclude our discussion, and the fourth annual Volcano Awareness Month (January 2013), with a look at the 1959 eruption of Kilauea Iki.

The eruption started on November 14, 1959, with a fissure that broke through the south wall of Kilauea Iki Crater at about 8:00 p.m., HST. Within 24 hours, the eruption focused on a single vent, from which a fountain fed lava into Kilauea Iki Crater until November 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 Pu`u Pua`i cone and filled Kilauea Iki Crater to a depth of about 130 m (425 ft). One of the fountains was the tallest ever observed at Kilauea’s summit, reaching an amazing 580 m (1,900 ft)! The eruption ended on December 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 Hawai`i 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 55 km (34 mi) 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 (the nature of the lava erupted in November and December subsequently confirmed the deep origin). A few weeks later, new tilt-monitoring stations began recording inflation, which was a sign that magma was accumulating just beneath the summit caldera.

Once the eruption started, Kilauea Iki crater began to fill rapidly 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 month-long 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 60 km (37 mi) 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. In fact, that model for Kilauea’s magma system is considered largely accurate even today, over 50 years after it was first proposed. The 1959 eruption can therefore be considered the start of our modern understanding of how Kilauea works.

We hope you have enjoyed this series of articles on noteworthy Hawaiian eruptions and the scientific advances they made possible, as well as other events associated with Volcano Awareness Month.

Best wishes for a happy and safe 2013 from the staff of the Hawaiian Volcano Observatory!