Unified Interior Regions


The Pacific Region has nine USGS Science Centers in California, Nevada, and Hawaii. The Regional Office, headquartered in Sacramento, provides Center oversight and support, facilitates internal and external collaborations, and works to further USGS strategic science directions.

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Lava fountain 450 m (1,475 ft) high from Kīlauea Pu‘u ‘Ō‘ō eruption...
September 19, 1984

Lava fountain 450 m (1,475 ft) high from Kīlauea Pu‘u ‘Ō‘ō eruption...

Lava fragments ejected by lava fountains are called tephra, a general term for all fragments, regardless of size, that are blasted into the air by explosive activity. A variety of terms are also used to describe specific types of fragments, including Pele's hair, Pele's tears, scoria, spatter, bombs, and reticulite. Other terms are used to describe the size of fragments,

Low lava fountains from 1984 Mauna Loa "2,900-m vents" signaled dec...
April 8, 1984

Low lava fountains from 1984 Mauna Loa "2,900-m vents" signaled dec...

Lava production from these "2,900-m vents" began to decrease in late March but declined most rapidly between April 7 and 9 from about 300,000 m3 per hour to less than 100,000 m3 per hour. Photo taken at 9:09 a.m.

Lava flows from the 1984 eruption of Mauna Loa loom above the town ...
April 4, 1984

Lava flows from the 1984 eruption of Mauna Loa loom above the town ...

Lava flows from the 1984 eruption of Mauna Loa loom above the town of Hilo. Photograph taken near the Hilo airport on April 4.

April 2, 1984

Mauna Loa Lava Flow, April 2, 1984

A USGS scientist walks along a lava flow from the April 2, 1984 Mauna Loa eruption. The scientist stops to observe a standing wave of lava at the end. The lava flow is moving at 64 km/hr (40 mph) towards Hilo, Hawai'i. 

Lava fountains erupting from fissure on upper northeast rift zone o...
March 25, 1984

Lava fountains erupting from fissure on upper northERZ of Mauna Loa...

Pohaku Hanalei cinder-spatter cone (upper left) is located about 3.2 km (2 mi) NE from the north edge of the caldera rim. Eruption rates were as high as 2.9 million m3 per hour during the first 6 hours of the eruption, then diminished to about 0.5 million m3 per hour for the next 12 days. Sizable pahoehoe flows formed only during the first day of the eruption and within a

Red hot lava erupts vertically in the air from a cone of black, hardened lava
September 6, 1983

Low fountain of lava from Pu'u 'O'o, Kilauea Volcano, 1983

Low fountain, approximately 50 meters high, from Pu'u 'O'o on Hawai'i Island's Kilauea Volcano (viewed from the north). Lava issuing from the breach in the northeast rim of the crater produced an 'a'a flow that extended more than 4 kilometers. Eruption episode 8.

Red hot lava fountaining 100 meters into the air from a cone of hardened, black lava
September 6, 1983

100-meter lava fountain, Kilauea Volcano, 1983

Pu'u 'O'o fountain approximately 100 meters high during eruption episode 8 on Hawai'i Island's Kilauea Volcano. Dark clots of spatter land near the base of the fountain, contributing to the growth of the cone. Less dense cinder, visible in the upper right, is carried downwind of the cone.

egg-shaped ball of red-hot lava with a blackened crust sitting on a bed of grass
July 23, 1983

Lava ball, Kilauea Volcano, 1983

Accretionary lava ball comes to rest on the grass after rolling off the top of an 'a'a flow in Royal Gardens subdivision on Hawai'i Island's Kilauea Volcano. Accretionary lava balls form as viscous lava is molded around a core of already-soldified lava.

Flat-topped cinder cone with red-hot lava splattering out of the top and cascading down the sides.
June 29, 1983

Pu'u 'O'o cinder-and-spatter cone, Kilauea Volcano, 1983

View at dusk of the young Pu'u 'O'o cinder-and-spatter cone, with fountain 40 meters high, on Hawai'i Island's Kilauea Volcano (episode 5).

A stream of red hot lava arcs into the air and splatters down on cooler, black lava flows
February 25, 1983

Arching fountain of lava, Kilauea Volcano, 1983

Arching fountain of lava approximately 10 meters high issuing from the western end of the 0740 vents, a series of spatter cones 170 meters long, south of Pu'u Kahaualea on Hawai'i Island's Kilauea Volcano (episode 2). Episodes 2 and 3 were characterized by spatter and cinder cones, such as Pu'u Halulu, which was 60 meters high by episode 3.

Photo showing a dozen narrow, blackened tree trunks with a crusted layer of black lava clinging to the bottom of each tree
January 7, 1983

Forest of lava trees, Kilauea Volcano, 1983

Forest of lava trees resulting from eruption of a 1-km-line of vents east of Pu'u Kahaulea on Hawai'i Island's Kilauea Volcano. The bulbous top of each lava tree marks the high stand of the lava flow as it spread through the trees. As the fissure eruption waned, the flow continued to spread laterally; its surface subsided, leaving pillars of lava that had chilled against

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April 7, 1995

April 10th marks the aniversary of the 1926 eruption of Mauna Loa Volcano. The eruption was preceded by several widely felt earthquakes about one hour before the outbreak of lava, and volcanic tremor was recorded on the few seismigraphs installed on the island about a half hour before the felt earthquakes. 

Kīlauea eruption status, May 13, 1994...
March 31, 1995

The 12-year long eruption along Kīlauea's east rift zone continued without interruption during the past two weeks. 

Deep earthquakes and lithospheric flexure...
March 24, 1995

Last Sunday evening, March 19, the Hawaiian Islands were shaken by a moderate earthquake located south of Kahoolawe and west of Hawaii. The earthquake occurred at 10:30 p.m., had a magnitude of 4.5, and was located about 30 miles deep.

Kīlauea eruption status—lava flows moving toward sea...
March 19, 1995

Kīlauea's 12-year-old East Rift Zone eruption continues with lava issuing from vents on the southwest flank of Pu'u 'O'o.

March 10, 1995

The "Volcano Watch" column from January 22, which provided information about earthquake damage from the Kobe earthquake in Japan and then described some ways to reduce damage from future earthquakes here in Hawaii, has generated quite a lively discussion in the "Letters to the Editor" section of the Hawaii Tribune Herald.

March 3, 1995

The U.S. Geological Survey has been working with the JASON Project, which began filming this past Monday in Hawaii Volcanoes National Park, to produce a series of interactive, live, educational broadcasts aimed at classes from upper elementary grades to high school. 

February 24, 1995

I want to thank all of you who came to our first-ever open house this past Monday. The number of people who wanted to see what we do and how we do it was most gratifying. It certainly made sprucing up the Observatory for company worthwhile.

February 17, 1995

The U.S. Geological Survey' Hawaiian Volcano Observatory, National Biological Service, National Park Service, University of Hawaii at Hilo, Kīlauea Military Camp, McDonnell Douglas Aerospace, NASA, and The Planetary Society invite the public to a special "Day in the Park" on Monday, February 20, 1995.

February 5, 1995

From February 13-18, the USGS Hawaiian Volcano Observatory and the National Park Service will host a team of scientists and engineers from NASA, McDonnell Douglas Aerospace and the JASON Foundation for Education at the Kīlauea caldera for a series of tests using a robotic vehicle designed for use on the moon and Mars.

Kīlauea's eruptive history...
February 3, 1995

The current activity along Kīlauea's east rift zone is the longest-lived eruption of Kīlauea in historic times. However, the historic period on Kīlauea dates only to 1790, and the first well-documented eruption took place in 1823.

January 27, 1995

The eruption on Kīlauea's east rift zone has continued without interruption since the last brief pause at the end of November.

January 20, 1995

The magnitude 7.2 earthquake in Kobe, Japan has resulted in extensive damage and a shocking number of fatalities and injuries. Japan has not experienced such a damaging earthquake since 1923, when an estimated magnitude-8.3 earthquake killed about 143,000 people in the Tokyo area.