# Volcano Watch — The Kapoho eruption—40 years old this week

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This Thursday, January 13, marks the 40th anniversary of the Kapoho eruption, the sequel to the Kīlauea Iki eruption in November-December 1959. It was far from being just a Kīlauea Iki 2, though, as residents of Kapoho and Koae villages were unfortunately to discover.

This Thursday, January 13, marks the 40th anniversary of the Kapoho eruption, the sequel to the Kīlauea Iki eruption in November-December 1959. It was far from being just a Kīlauea Iki 2, though, as residents of Kapoho and Koae villages were unfortunately to discover.

Seismicity began in lower Puna in late December, less than a week after the eruption at Kīlauea's summit ended. Hundreds and then thousands of earthquakes occurred daily by January 12, when many were being felt in and near Kapoho. And up they came, shallowing early on January 13, so much so that ground cracks opened across the Pahoa road on the west edge of Kapoho. These cracks indicated that the Kapoho fault had been reactivated. This fault dropped part of the village down 3.5 m (12 feet) in 1924 and another several tens of centimeters (several inches) during the 1955 eruption. The rejuvenated fault quickly extended downrift to Puu Kukae.

By 9 a.m. on January 13, movement along the fault on the north side of the downdropped block-called the Kapoho graben-had cut off the road to the village of Koae. Fears of an impending eruption led to voluntary evacuation of Kapoho, starting in mid-morning and completed by nightfall. Until 3 p.m., the earthquakes, cracking, and faulting continued, and then a eerie quiet pervaded the area.

This was the lull before the storm, for fountains began at 7:35 p.m. from a 900-m-long (3,000-ft-long), northeast-trending fissure only 600 m (2,000 ft) northwest of Kapoho. This ushered in 37 days of uninterrupted eruption between Kapoho and Cape Kumukahi.

Before the eruption ended, Kapoho village and part of Koae village were overwhelmed by lava. Warm Springs, a swimming and picnic area at the base of Puu Kukae, was destroyed. Higashi Pond, a 900-m-long (3,000-ft-long) embayment created northeast of Puu Kukae by ground subsidence in 1924, was filled by January 20. The coastline from Cape Kumukahi northwest to beyond Kipu Point grew seaward as much as 750 m (2,500 ft). In fact, the name, Cape Kumukahi, had to be transferred a little northeast to retain its claim as the easternmost point in Hawaii. Two hastily planned and constructed lava barriers, bulldozed near Puu Kukii to protect Warm Springs, Kapoho, and Kapoho Beach Lots, eventually failed beneath the relentless aa flows.

On January 13-14, one of the most remarkable events took place-roaring emission of black clouds of steam and volcanic ash from vents alongside, and sometimes alternating with, lava fountains. This was apparently caused by brackish groundwater gaining access to the conduits. The steam bursts took place between 11:15 p.m. and 10:30 a.m. and produced ash that blanketed the area with a thin coating of tiny glass particles. Sea salt formed as the ash dried-clear evidence of the involvement of salty water.

The Kapoho graben played an important role during the eruption. It was (and still is) a low area dropped by faulting, and served to channel lava northeastward away from the vents near Kapoho. That is why the lava advanced so far east; without the graben, the flow would probably have moved southward around Kapoho Cone or northward toward Nanawale.

When the eruption ended on February 19, a high cinder and spatter cone, now called Puu Laimana (Lyman), rose above the main vents of the fissure. This material, produced by fountains as high as 365 m (1,200 ft), is now quarried for nursery beds. Flows eventually covered 10 square kilometers (2,500 acres) with 120 million cubic meters (160 million cubic yards) of lava. Revegetation and cultivation are rapidly obscuring parts of the area, but the desolate drive down the road to the lighthouse kipuka reminds one of the events of 40 years ago and provides a heads-up for what will happen in the future. Starting on January 13, see our web site (hvo.wr.usgs.gov) for a more complete and illustrated account of this notable eruption.

### Volcano Activity Update

Eruptive activity of Kīlauea Volcano continued unabated during the past week. Lava is erupting from Puu Oo and flowing through a tube to the seacoast. The ocean entry at Lae`apuki has been active all week, adding to the bench that now extends about 400 m (1,300 feet) along the shoreline. Viewing has been good at night between the end of the Chain of Craters Road and Highcastle. The public is reminded that the ocean-entry area is extremely hazardous, with explosions accompanying unpredictable collapses of the new land. The active lava flow is hot and has places with very thin crust. The steam clouds are highly acidic and laced with glass particles.

Another flow is slowly approaching the eastern boundary of the National Park near the Royal Gardens access road. A third is poised to descend Pulama pali just inside the Park.

There were no earthquakes reported felt during the week ending on January 6.