Recent Activity at Loihi Volcano

Updates on Geologic Activity at Loihi

This document summarizes recent volcanic and earthquake activity at Loihi. Details of from specific time intervals can be found by visiting the detailed update pages listed below. You can also learn more about results of recent subject-specific research on Loihi by following the links in the lower button bar.

SMALL EARTHQUAKE SWARM RATTLES LOIHI IN DEC 2005     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).

LARGEST EARTHQUAKEs TO HIT LOIHI IN 2005....     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). NO M>4 EARTHQUAKES WERE DETECTED AT LOIHI IN 2002, 2003 OR 2004

HUGO RECOVERED FROM THE OCEAN FLOOR IN NOV 2002     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.

MULTIPLE EARTHQUAKES DETECTED AT LOIHI SINCE 10 SEPT 2001     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).

LOIHI OBSERVATORY FIXED; VOLCANO INTERMITTENTLY MAKING "ERUPTION NOISES" (Jan-Feb 1998):     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. LOIHI OBSERVATORY DEPLOYED/LOIHI ERUPTING AGAIN? (Oct 1997):     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.

LOIHI WENT SEISMIC (July 1996):     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.

MORE DETAILS of EVENTS SINCE THE 1996 ERUPTION (1997 through 1998):     More details of events during this period can be found on the Early 1998 and Mid-Late 1997 Update Pages. The first half of 1998 has been pretty uneventful at Loihi (as far as we can tell, of course). Manned-submersible dives using HURL's Pisces V submarine are currently underway.     A manned-submersible exploration program during August and September of 1997 observed the glistening water of high temperature hydrothermal fluids issuing from vents within the newly-formed (1996) Pele's Pit and measured water temperatures of up to 200 C. Also observed were high temperature hydrothermal mineral deposits (similiar to those observed on Mid-Ocean Ridge volcanoes) that were unlike lower temperature materials found previously at Loihi and wide-spread deposits of young-appearing volcanic sand on the summit. More manned-submersible observations of the seamount are presently underway (Sept-Oct 1998). A single dive to Pele's Pit indicated that most vents have cooled somewhat since last year, with maximum temperatures of about 160 C. Unfortunately, an additional 5 dives to the seamount had to be canceled this past week due to bad weather conditions. Hopefully, some of the remaining 10 or so dives planned for the next 2 weeks (thru mid-october 1998) will be able to be executed at Loihi.     During the initial deployment of HUGO (Hawaii Undersee Geo Observatory) in Oct. 1997, a hydrophone on the Loihi summit recorded noises that could be interpreted as eruption-related. Unfortunately, the HUGO communications system stopped communicating a few days later and when it came on-line again on 19 Jan 1998, the volcano was quiet. It was determined during this Jan visit by the the Pisces V submersible that the observatory had stopped working in October because a connector regulating power to the "Junction Box" on HUGO had flooded with seawater. The Junction Box sits at the termination of the fiber optic and electronic cable connecting HUGO to the Big Island of Hawaii. 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 during sub dives the volcano itself was quiet. Then, in Feb 1998, continuous real-time monitoring by a hydrophone on HUGO revealed that Loihi was apparently erupting again (based upon transient acoustic signals recorded on the hydrophone). During this time, The R/V Maurice Ewing was shooting siesmic reflection lines in the area of Loihi Seamount, making three passes directly over the HUGO site. Work is underway to determine if they recorded any of these transient events on their receivers in order to precisely locate the eruption site. Unfortunately, HUGO stopped communicating to shore in late April 1998 and it is uncertain if the fault is in the shore to HUGO cable or the HUGO terminus of this cable. Repairs will probably not be affected until Fall 1998, when manned submersible dives are will be conducted. These will focus mostly on the geology summit area. Stay tuned for reports after those dives. SUMMARY OF THE 1996 ERUPTION AND SEISMICEVENT (Compiled from the research of many individuals; Details of detection and initial response to seisimic activity is given on the 1996 Eruption and Intro to Seismic/Volcanic Event Page) For 2 months during the summer of 1996, the largest swarm of earthquakes ever recorded on ANY Hawaiian volcano occurred at Loihi seamount. It began on 17 July 1996 and by the end of August, a total of over 4000 earthquakes have been recorded by the Hawaii Volcano Observatory (HVO) network, with more than 40 earthquakes between magnitude 4 and 5 recorded by the World Wide seismic network. In August 1996, a National Science Foundation-funded expedition to Loihi by UH scientists began investigating this unique event and its origin. The following are some of the results: There was at least one, possibly two eruptions at Loihi in 1996, based on radiometric dating of young lavas collected by manned-submersible from Loihi The summit of Loihi has undergone some drastic changes in 1996, including the formation of a third new pit crater and deposition of large quantities of glassy sands and gravels on the southern part of the summit platform New vents issuing the hottest waters ever observed at Loihi (up to 200 ° C) are present in the new pit crater The water column above Loihi has signatures of enhanced hydrothermal activity at or near the summit LINKS to DETAILED UPDATES on GEOLOGIC ACTIVITY AT LOIHI. (Listed most recent date first) Details about various aspects of activity at Loihi can also be obtained by using the links in the buttonbar above. Early 1998 Info from recently-conducted manned-submersible dives on Loihi to the HUGO site. Mid-Late 1997 Info from recently-conducted manned-submersible dives on Loihi and from continued on-going shore-based research. Early-Mid 1997 Updates from continued on-going shore-based research. 1 - 30 Nov. 1996 Updates from on-going shore-based research on Loihi following followup expeditions of last month. 1 - 31 Oct. 1996 Info from followup expeditions to Loihi after the initial event response cruise 18 August - 31 Sept. 1996 Includes post-Event Response cruise wrap-up and initial discussion of analyses and results. 11-17 August 1996 Includes post cruise wrap-up and discussion of early analyses on samples collected. 4-10 August 1996 Includes three reports from scientists while they were aboard the ship on the initial Event Response Expedition: 8-9 Aug 1996 8 Aug 1996 6-7 Aug 1996 17-31 July 1996 Early discussion of these earthquakes and hypotheses about what may have been causing them.

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