General information about Loihi is on this page. Links to a Virtual Tour of Loihi and to Details of recent seismic/volcanic/hydrothermal activity are from the buttons in the image above.
The beige area of the update button bar leads to the main update page; blue buttons lead to details pages

Links: [General Info |Virtual Tour |1996 Eruption Summary |1996 Eruption Details |Seismicity |Rock Gallery |Rock Chemistry |Hydrothermal Vents |Expeditions |Updates ]


General Information About Loihi

    Loihi seamount, sometimes known as the "youngest volcano" in the Hawaiian chain, is an undersea mountain rising more than 3000 meters above the floor of the Pacific Ocean (Loihi is the red-capped nub that is pointed out in the of the image above). Both Loihi and Kilauea volcanoes sit on the flank Mauna Loa volcano, an older, larger, and still active volcano on the Big Island of Hawaii. Loihi sits submerged in the Pacific off of the south-eastern coast of the Big Island of Hawaii (this is the grey area labeled "Hawaii" at the top of the image). Although hidden beneath the waves, Loihi is nevertheless taller than Mt. St. Helens was prior to the catastropic volcanism there in 1980.
    Before to the 1970's, Loihi was not known to be an active volcano. Instead, it was thought to be a fairly common old seamount volcano of the type that surrounds the Hawaiian islands. These latter volcanoes are similar in age (80-100 million years old) to the sea floor upon which the Big Island of Hawaii sits. This sea floor was itself created some 6000 km away on the undersea volcanic mountain chain known as the East Pacific Rise. It has slowly moved north-westward to the present location of the Hawaiian Hotspot.
Volcanoes on the 
Big Island with Loihi highlighted

    In 1970, our ideas about the seamount changed drastically following an expedition that went to Loihi to study an earthquake swarm (intense, repeated seismic activity) that had just occurred there. It was revealed that Loihi was a young, active volcano, rather than an old dead seamount from a bygone aeon. The volcano is mantled with young and old lava flows and is activly venting hydrothermal fluids at it's summit and south rift zone. In August 1996 Loihi volcano rumbled to life again with a vengence and has been intermittantly active since then (as described below and elsewhere at this web site). In fact, University of Hawaii scientists studying the seamount following the 1996 seismic swarm have found direct evidence of a volcanic eruption there in 1996, making this the first confirmed historical eruption of the seamount.
    Loihi shares the Hawaiian hot spot with its larger active siblings Mauna Loa and Kilauea. You can view a schematic representation of the geometry of this situation HERE. If you would like to learn more about how the Hawaiian islands formed from a single mantle hotspot, visit the Formation of the Hawaiian Islands web page at this site.


What's up at Loihi Today?
Get more details on the Loihi Update page

    The USGS-ANSS (Advanced National Seismic System) reports that small swarm of about 100 quakes (the largest 3 were about 4 magnitude and between 12 and 28 km deep) occured beneath Loihi on Dec. 7 2005. A more recent quake (estimated magnitude of 4.7) occured on 18 Jan 2006, roughly midway between the Loihi and Pahala (on the S. Coast of the Big Island).

    The USGS-ANSS reported that magnitude 5.1 and 5.4 quakes occurred beneath Loihi on 13 May and 17 July (both at 44 Km depth), and a magnitude 4.3 quake occurred on 23 April at about 33 km depth).


    The Hawaii Undersea Geo-observatory (HUGO) has been recovered after 5 years on the Loihi summit. UH Prof. Fred Duennebier, who developed the observatory, expects to put it back on Loihi in a few years after improving it with new technology and protecting the power/communications cable with steel armor.

    Increased seismicity in the form of a swarm of earthquakes began at Loihi's summit with quakes up to magnitude 5.2 on 13 sept 2001. Activity continuued for a couple of weeks, with 4 events >M4 at depths of 12-13Km (See the 2001 Update Page for details).

    The Hawaii Undersea Geo-Observatory (HUGO) was visited by the Pisces V submersible for the first time on 19 Jan since it was installed in October 1997. The observatory stopped working in October when a connector regulating power to the "Junction Box" at the end of the cable connecting it to the Big Island of Hawaii flooded with seawater. The failed connector, was successfully repaired and a hydrophone (underwater microphone) was installed. Immediately after installing the hydrophone whale sounds were heard at the listening station at Honuapo, Hawaii, but the volcano itself was quiet.
    Continuous real-time monitoring revealed in Feb that Loihi again appears to be erupting. This is based upon transient acoustic signals recorded on the hydrophone. The R/V Maurice Ewing is currently shooting reflection lines in the area with three passes directly over the HUGO site. If they record any of these transient events, which appears likely, then it should be possible to precisely locate the eruption site.

    A hydrophone deployed during the 2nd week of October (1997) at the newly-installed Hawaii Undersea Geo Observatory site on the summit of Loihi began recording intense, thunder-like noises from the summit region within a day of deployment. Unfortunately, the system stopped communicating a few days later and won't come on-line again until submersible dives in Jan 1998. These sounds, which have not been detected since surveys in Summer 1996, may be related to a new eruption.

LOIHI GETS HOT (Sept 1997):
    Recent observations made during manned-submersible dives in August and September 1997 revealed that Loihi is now supporting high-temperature hydrothermal venting at its summit. 200 ° C water was recently detected, which is substantialy higher than the 77 ° C water measered in the Pele's Pit region of Loihi immediately following the Seismic event last year.

    During the summer of 1996, the largest swarm of earthquakes ever recorded on ANY Hawaiian volcano shook Loihi seamount. The swarm began on 17 July 1996; to date, a total of over 4000 earthquakes have been recorded by the Hawaii Volcano Observatory (HVO) network. Click HERE to see a location map with of earthquake epicenters. Learn more about this event and recent activity at Loihi on the 1996 Loihi Eruption Pages.


    The image to the left is a shaded "Bathymetric map" of Loihi Seamount as it now looks, following the July 1996 eruption and seismic event. The 3 depressions in the summit area are "pit craters"; the lower-left most crater was formed in July 1996.
    "Bathymetry" refers to the depth from the ocean's surface to features on the seafloor. As you might expect, low numbers on a depth map refer to shallow regions, or the high point on a submarine mountain such as Loihi. Shallow regions are given in warm colors on this map; cool colors are the deep regions. Map made by UH graduate student Nathan Becker using 1997 seabeam bathymetry and the GMT program
   A bulbous pillow lava from Loihi's summit area. Most of the rocks to be found on Loihi's summit are coated by some amount of fine sediment and/or clay minerals that come from the interaction of sea water with the rock's surface. Only the very youngest rocks typically are sediment-free in this environment. You can see examples of the latter on our Rock Gallery page. You can also learn about the Chemical compositions of young rocks from Loihi at this web site. Photo by Mike Garcia


Other web resources about Loihi

Awards we have received for the HCV site are displayed on our main page. The Loihi Sub Site has specifically received this additional award
Key Resource A Links2Go
Key Resource Site


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This page created and maintained by Ken Rubin©,
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Last page update on 19 Jan 2006