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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).
THE 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. The cable (between Loihi and the Big Island) that provided HUGO power and communications, broke in 1998, effectively shutting down the recording instruments. 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 on 10 sept 2001 at Loihi's summit with quakes up to magnitude 5.2. Activity continued for about 2 weeks. See the 2001 Update Page for details.
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)
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Last page update on 20 Jan 2006