June 20, 1997

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

The Valley of Ten Thousand Smokes

A popular local morning radio program had a contest early last week, and the question posed was "Where is the Valley of Ten Thousand Smokes?" Listeners called in with answers ranging from Tennessee to California before the correct answer of Alaska was given.

The Valley of Ten Thousand Smokes (VTTS) is the product of the most voluminous eruption in this century. Starting at 1 p.m. on June 5, 1912 and continuing for about 60 hours, 25 cubic kilometers of air-fall tephra and 15 cubic kilometers of ash-flow tuff erupted from Novarupta caldera located ten kilometers west of Mount Katmai on the Alaska peninsula opposite Kodiak Island.

To impress upon you the size and rate of the VTTS eruption, the cumulative volume of the ongoing activity of Kilauea Volcano since January 3, 1983, as measured by geologists of the U.S. Geological Survey's Hawaiian Volcano Observatory, is 1.5 cubic kilometers. The daily output is slightly more than 300,000 cubic meters. The eruption rate of VTTS averaged nearly a billion cubic meters an hour!

Although the VTTS eruption occurred in 1912 and several expeditions were sent to the area of Mount Katmai, the Valley of Ten Thousand Smokes was not discovered until 1916. The remoteness of the region is the probable reason why no deaths are attributed to this huge eruption.

The name came aptly to the National Geographic Society expedition leader who viewed the countless fumaroles covering the entire 162 square kilometer surface area of the deposit. Steam from water contacting the hot ash-flow tuff unit comprised 98% of the fumarolic gases, and the other two percent came from volcanic gases escaping the cooling and deflating layer. This vast fumarolic phenomenon continued into the 1930's.

The products and events of the 1912 VTTS eruption have enlightened volcanologists in several aspects. Three distinctive rock units together with their mixtures indicated that the eruption tapped a highly zoned magma storage area or three weakly connected storage bodies. The large collapse of the summit region of Mount Katmai, 10 kilometers to the east, showed that the magma storage body located there was hydraulically connected to the erupting vent.

VTTS provided an ideal setting for understanding the relations between pyroclastic fall and flow deposits, and it is one of the few historic eruptions to have produced welded tuff.

In 1918, the Valley of Ten Thousand Smokes and the surrounding Katmai area were declared a National Monument. Katmai National Monument was expanded in 1931 and again in 1942, and now is second only to Yellowstone National Park in size of the areas administered by the National Park Service.

If a radio listener had answered Kamchatka, she would have been correct because the ash flow field of the 1956 explosion of Bezymianny Volcano is also called the Valley of Ten Thousand Smokes. Galunggung Volcano in Indonesia formed the prehistoric Ten Thousand Hills of Tasikmalaya, but no name is given to the Pinatubo Volcano ash flow field that also has countless steaming fumaroles. By volume, the June, 1992 eruption that produced that deposit was the second largest of this century. Havana, Cuba is definitely a wrong answer.

Kilauea Eruption Status--June 20

Kilauea's east rift zone eruptive activity continued during the past week with intermittent action from three vents. On Monday afternoon, lava flowed out of Pu`u `O`o crater for the first time since July, 1986. After two hours of outpouring over the western rim, lava activity within the crater stopped, and the floor subsided several meters. Fountains from the west flank vent have reached heights of 50 meters and have provided visitors to the NPS Pu`u Huluhulu viewing area with a memorable display. Flows from the west and southwest vents extend up to 2 kilometers from the cone. An extended lava flow with a tube system has not developed because activity shifts among the three vents with no vent being active longer than a day.

Recent Big Island Earthquakes

Kona residents were shaken by a magnitude 3.7 earthquake at 2:27 a.m. on Monday morning. The temblor was located 19 km northwest of Keahole Point at a depth of 12 km.