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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Large cracks in active lava delta, Kīlauea Volcano...
May 19, 2006

Large cracks in active lava delta, Kīlauea

Substantial cracks cutting across a lava delta are clear indication that the delta is subsiding as it grows across the unstable pile of interfingering lava flows and fragments built on the steep submarine slope. The larger cracks on this delta are 1-2 m (3-6 ft) wide. Lava flows spread onto the delta from some of the cracks and then, after solidifying, were cut by renewed

Active lava delta on southeast coast of Kīlauea Volcano, Hawai‘i...
May 19, 2006

Active lava delta on SE coast of Kīlauea, Hawai‘i

Lava delta at East Lae‘apuki on the southeast coast of Kīlauea Volcano is about 17 hectares (43 acres). The delta extends about 400 m seaward from the sea cliff and is about 850 m long parallel to the shoreline. The steep sea cliff embayment resulted from collapses of earlier deltas; the collapses undermined and took away parts of the cliff. Note similar inactive delta

Juvenile ‘i‘iwi in the hand
April 10, 2006

Multi-colored juvenile ‘i‘iwi

‘I‘iwi are one of the most charismatic Hawaiian honeycreepers extant today. Their long, curved bill allow them to reach nectar deep inside specially evolved Hawaiian flowers. As they mature, juvenile ‘i‘iwi will go from these mottled, multi-colored feathers to bright red coloration. 

March 22, 2006

Shatter Ring on the PKK Lava Tube

(March 20, 2006, 11:30:10 to March 22, 2006, 07:00:16) The flow field feature seen here in profile is a shatter ring. Shatter rings are circular to elliptical volcanic features, typically tens of meters in diameter, that form over active lava tubes (Kauahikaua and others, 2003; Orr, 2011) They are typified by an upraised rim of blocky rubble and a central depression.

US Army helicopter flies over the heads of researchers on Mauna Kea
February 23, 2006

US Army helicopter flies over the heads of researchers on Mauna Kea

A US Army helicopter from Pohakuloa Training Area flies overhead of palila researchers on Mauna Kea volcano, Hawai‘i Island, Hawai‘i. 

Poster laid out with photos, images, and text.
December 31, 2005

Mud Damages Hawaiian Coral Reefs

Large-scale poster describing USGS work.

Scientists from the USGS, the University of Hawaiʻi (UH), and the University of Washington (UW) are studying the coral reefs near several Hawaiian islands. Using air photos, satellite photos, underwater photos, and underwater instruments, we've found that mud washed offshore by large storms can damage coral reefs. Corals need

November 28, 2005

Lava Delta Collapse at East Lae‘apuki

At 11:10 in the morning on November 28, 2005, the lava delta at the East Lae‘apuki ocean entry, on Hawai‘i's southeastern coast, began to collapse into the ocean. This was not a catastrophic failure of the 13.8-hectare delta, but instead occurred by piecemeal calving of the front of the delta over a period of just less than 5 hours. The collapse removed nearly the entire

Nene adults and goslings in a grassy field
November 27, 2005

Nene adults and goslings

A mating pair of adult nēnē (Branta sandvicensis) keep a close watch on three young goslings. An endangered species and the state bird of Hawai‘i, nēnē are the last remaining species of Hawaiian goose.    

Kīlauea Volcano's east Lae‘apuki lava delta after 70-100 m (230-330...
August 27, 2005

Kīlauea's east Lae‘apuki lava delta after 70-100 m (230-330 ft) lon...

Embayment of lava delta shows result of collapse. The initial collapse was large enough to send waves washing over much of the east half of the delta, because visibility was completely lost for almost 20 minutes, due to a steam white-out. Note rocky debris hurled by the waves onto the delta surface in foreground.

Kīlauea Volcano's east Lae‘apuki lava delta pictured hours before i...
August 26, 2005

Kīlauea's east Lae‘apuki lava delta pictured hours before it collap...

Kīlauea Volcano's east Lae‘apuki lava delta pictured hours before it collapsed into the sea over a 90-minute period. White plume marks location of lava entering sea fed by a lava tube within delta.

Lava spilling over sea cliff starts to build new lava delta, Kīlaue...
August 23, 2005

Lava spilling over sea cliff builds new lava delta, Kīlauea

pāhoehoe lava spilling over sea cliff on south coast of Kīlauea Volcano starts to build a new lava delta. Only three days old, the delta grows slowly as lava spreads over fragmented debris and flows that have accumulated on the steep submarine slope.

Tephra-jet explosion at leading edge of an active lava delta, Kīlau...
August 19, 2005

Tephra-jet explosion at leading edge of an active lava delta, Kīlauea

Explosive interaction between lava and seawater blasts a tephra jet consisting of steam, hot water, black tephra, and molten fragments into the air. Such explosions are typically directed toward the sea, but many explosions also send a shower of lava more than 10 to 20 m (33 to 66 ft) inland. Tehpra jets are the most common type of lava-seawater explosion, and typically

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August 23, 2001

What is the summit elevation of Mauna Loa? 13,677 feet (4168.7 m) according to the 1994 Hawai`i Volcanoes National Park brochure; 13,679 feet (4169.4 m) according to the 1998 Atlas of Hawai`i; and 4,169 meters, which equals 13,678 feet, on the 1996 Geologic Map of the Island of Hawai`i. Who is right? Perhaps all?

August 16, 2001

At 2:00 p.m. on Friday, August 17, the County of Hawai`i officially opened to the public a new viewing area of the current eruptive activity. The viewing area overlooks the spectacular seascape of the lava bench and accompanying black sand beach at the ocean entry east of Kupapa`u.

August 9, 2001

What's the difference between a bench and a boardwalk? Both offer a view of the sea, but while the latter is a pleasant place for a stroll, a walk on the lava bench can kill you.

August 2, 2001

Every few months HVO receives a phone call from a concerned citizen explaining that steam is billowing from a new hole in a yard or pasture. Is this foretelling the start of an eruption?

July 26, 2001

Surfers of our Hawaiian Volcano Observatory (HVO) web site might have noticed that, earlier this year, we rolled out a modified web presentation of earthquake activity in Hawai`i. An "After Dark in the Park" evening talk at Hawai`i Volcanoes National Park in June also described our new web pages and their operation.

July 19, 2001

Every so often we receive a number of inquiries from anxious people in Kona about a possible eruption of Hualālai Volcano. The latest spate of questions is apparently being triggered by a personal web site that contains inaccurate information about the volcano. We hope to dispel the rumors by presenting the results of our ongoing observations.

July 12, 2001

The ground surface subsided abruptly about six weeks ago at Pu`u `O`o, Kīlauea Volcano's active cinder-cone vent. Gaping cracks opened around the edges of the subsidence zone, centered on the southwest edge of the cone. A collapse pit about 30 m (100 ft) in diameter and 15 m (50 ft) deep nibbled into the cone's margin. 

July 5, 2001

A visitor recently asked, "Does Kīlauea erupt more often at the summit or along its two rift zones?" Let's try to answer that question.

June 28, 2001

A common sight this time of year, particularly in Puna and the National Park, is a bright yellow tripod topped with a white disk. Usually seen standing by the side of the road, these instruments are Global Positioning System (GPS) antennas, which scientists at the Hawaiian Volcano Observatory use to measure small ground motions. 

June 21, 2001

Few landscape changes are as extreme as that between the windward and leeward sides of Kīlauea's caldera. Simply drive from the Visitor Center in Hawai`i Volcanoes National Park to the Southwest Rift pullout along Crater Rim Drive.

June 14, 2001

The hot-spot theory is the well-known modern explanation for the origin of the Hawaiian island chain. In it, the Pacific plate drifts northwestward over a relatively fixed hot spot. Magma generated by the heat then penetrates the plate and rises to the surface, leaving a string of volcanoes.

June 7, 2001

Kīlauea wasn't always like it is today. Two hundred thousand years and the change from a seamount to an island can do a lot to a volcano. The trick is to determine what those changes were.