Recent Activity at Loihi Volcano
Events in Early 1998
Current Geologic Activity and Research at Loihi
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Please see previous Loihi update pages for pre-1998 events at Loihi
- Sept. through Oct. 1998 - New Submersible Observations are
So far, most of the planned dives to Loihi during the Fall 1998 dive
season have been called due to poor
weather conditions. One dive to Pele's Pit did reveal that waters issuing from
most of the hydrothermal vents there have cooled somewhat. The hottest
vents that were at 200 deg C last year are now at only 160 deg C and
still issuing as fairly diffuse flow. Hydrothermal chimney structures
are small and unconsolidated. A single CTD cast into the pit revealed that
bottom waters are still gassy with CO2 derived from the seamount,
resulting in a pH of about 5.98. As more details become availble in late
October 1998, a "late 1998" update page will be created.
- May through July 1998 - Not much going on
There is nothing new to report regarding geologic or
other activity on Loihi seamount. As far as we can tell using our
shore-based instrumentation, the seamount has been quite. A series of
manned-submersible dives using the Pisces V submarine are planned for
September of this year; hopefully, we will have a better idea of
recent goings on at the seamount after that time.
- Late April 1998 - HUGO is down
On 29 April, Fred Duennebier reported that the HUGO observatory
on Loihi has stopped communicating with the shore, due to a short circuit
to sea water in either the Loihi-to-shore cable or in the cable terminus at
HUGO (the "junction box"). Testing is underway to determine where the
short is. Repairs may not be able to be effected until Fall of 1998.
More details are available at the
HUGO web site.
- Mid Feb 1998 - LOIHI MAKING NOISES AGAIN
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 signals vary in frequency from
several Hz to several KHz, and in duration from seconds to minutes. One
type of signal begins with a low frequency roar followed by a high
frequency hiss that lasts for several minutes. This signal is repeated
several times per day. As of today, the location of the eruption site is
unknown, but it is less than 2 km from the
HUGO Junction Box,
based on the time difference between direct acoustic arrivals at the
HUGO hydrophone and the reflection from the ocean surface.
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
- Jan 19-20, 1998 -
LOIHI OBSERVATORY FIXED BUT THE VOLCANO IS QUIET
Fred Duennebier reported from the R/V Kaimikai-o-Kanaloa that 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 is quiet.
In dives later this week, scientists aboard the R/V "KOK"
will install another hydrophone and attempt to repair a seismic monitoring
instrument in preparation for an experiment later this month to study the
potential for landslides in the area. Divers also noted that the HUGO
junction box is now half-buried in volcanic mud, which should help to keep it
stable for many years to come.
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Last page update on 7 Oct 1998