Volcano Watch — Kīlauea's been a lively place for the past 1,000 years

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Some people think history is dull. Well, brace yourself. The past 1,000 years at Kīlauea have been anything but dull, providing an exciting, at times almost breathless, volcanic experience for people who arrived and settled the island during that time.

Lava flows finally began to erupt again about 1,000 years ago, breaking a 1,200-year-long interval dominated by explosive eruptions. Lava completely filled the summit caldera and stacked up to form a new shield—the Observatory shield—in place of the giant crater. Flows spilled into the surrounding forest, which had grown during the previous centuries, and lava erupted frequently along the east and southwest rift zones, as well.

Some archaeologists think people first arrived on the island during this time. Their most recent interpretation, published just last year, dates the arrival to the first half of the 13th century, 200–250 years after the Observatory shield started to form. ‘Ailā‘au, eater of the forest, reigned over the erupting volcano as flow after flow spread through the forest.

Construction of the shield ended in about 1400. Then a huge lava flow, the largest since people arrived here, began to pour from a vent near present-day Thurston lava tube. This flow, known as the ‘Ailā‘au flow, erupted for about 6 decades, starting in the early 1400s. By the time the eruption ended, most of Kīlauea north of the east rift zone was buried, and some lava spilled southward to modern Keauhou Landing.

The Observatory shield then collapsed, forming the modern caldera. This remarkable destruction took place—probably over a few days to weeks—sometime between 1470 and 1510; dating techniques can't be more precise, and we take 1500 as the birth year of the caldera.

Interpretations of chants suggest that Pele arrived just before the start of the ‘Ailā‘au flow, 150–200 years after settlement of the island, and that she used that flow to destroy the Puna forest because Hi‘iaka took so long to return from Kaua‘i with Lohi‘au. When Pele killed Lohi‘au in the tragic end of a love triangle, Hi‘iaka dug the caldera, trying to find Lohi‘au's body. If these interpretations are correct, then the Holo Mai Pele collection of mele and hula probably developed after 1500.

Towering lava fountains, likely more than 600 m (2,000 ft) high, roared from the caldera just after it formed, starting 300 years of explosive eruptions that ended only in the early 19th century. At least four eruption columns rose high into the jet stream, and ash fell east of the summit to, and beyond, Kalapana. Pele may have used one eruption, in about 1650, to chase Kamapua‘a into the sea. The deadly 1790 eruption was the largest and one of the latest during this period. Explosive eruptions reflect Pele's temper; just as we throw things when angry, so does Pele.

Only a few lava flows were erupted during the 300 years of explosive activity, but this changed in 1823, when the volcano meekly reverted to an effusive interval that continues to this day. The 2.5 weeks of explosive eruptions from Halema‘uma‘u in 1924 was a brief, violent tantrum, but the explosions were small compared to those between 1500 and 1800.

The past 1,000 years tell a fascinating story of effusive and explosive activity that reshaped Kīlauea's summit and strongly influenced society on the volcano. The next 1,000 years will probably be no different, though the impacts on people will likely be even greater as population and, consequently, risk increase, particularly if Kīlauea enters another long cycle of violent explosive activity.

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Volcano Activity Update

A lava lake present within the Halema‘uma‘u Overlook vent during the past week resulted in night-time glow that was visible from the Jaggar Museum overlook. The lake, which is normally about 80–115 m (260–380 ft) below the floor of Halema‘uma‘u Crater and visible by HVO's Webcam, rose and fell slightly during the week in response to a series of deflation-inflation cycles. A series of brief rise-fall cycles on April 14–15 brought the lava level to about 65 m (210 ft) below the floor of Halema‘uma‘u Crater.

On Kīlauea's east rift zone, surface lava flows were active on the pali and coastal plain in the Royal Gardens subdivision over the past week. As of Wednesday, April 18, the flows on the coastal plain were advancing towards the ocean but were still about 1.2 km (0.7 miles) from the water.

One earthquake beneath Hawai‘i Island was reported felt this past week. A magnitude-2.8 earthquake occurred at 1:42 p.m., HST, on Monday, April 16, 2012, and was located 8 km (5 mi) northwest of the summit of Mauna Kea at a depth of 28 km (17 mi).