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).
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)
- 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
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.
This page created and maintained by
Ken Rubin,©
krubin@soest.hawaii.edu
Other credits for this web site.
Last page update on 20 Jan 2006
