Available Weekly Reports
12 September-18 September 2001
An earthquake swarm occurred at Loihi during 10-11 September and two 13 September earthquakes may have also been part of the swarm. The two later earthquakes occurred at 0311 and 0839 and had magnitudes of 4.9 and 4.4, respectively. Most of the earthquakes from 10-13 September were ~12 km deep and located slightly S of the summit of the volcano.
Sources: US Geological Survey Hawaiian Volcano Observatory (HVO)
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5 September 2001Back to Top
Summary of eruption dates and Volcanic Explosivity Indices (VEI).
|Start Date||Stop Date||Eruption Certainty||VEI||Evidence||Activity Area or Unit|
|1996 Feb 25 ± 30 days||1996 Aug 9 (?)||Confirmed||0||Historical|
|[ 1986 Sep 20 ]||[ 1986 Sep 20 ]||Uncertain||0|
|[ 1984 Nov 11 ]||[ 1985 Jan 21 ]||Uncertain||0|
|[ 1975 Aug 24 (?) ]||[ 1975 Nov ]||Uncertain||0|
|[ 1971 Sep 17 ]||[ 1972 Sep ]||Uncertain||0|
|50 BCE ± 1000 years||Unknown||Confirmed||0||Potassium-Argon|
|5050 BCE ± 1000 years||Unknown||Confirmed||0||Potassium-Argon|
|7050 BCE ± 1000 years||Unknown||Confirmed||0||Potassium-Argon||East flank?|
Loihi seamount, the youngest volcano of the Hawaiian chain, lies about 35 km off the SE coast of the island of Hawaii. Loihi (which is the Hawaiian word for "long") has an elongated morphology dominated by two curving rift zones extending north and south of the summit. The summit region contains a caldera about 3 x 4 km wide and is dotted with numerous lava cones, the highest of which is about 975 m below the sea surface. The summit platform includes two well-defined pit craters, sediment-free glassy lava, and low-temperature hydrothermal venting. An arcuate chain of small cones on the western edge of the summit extends north and south of the pit craters and merges into the crests of Loihi's prominent rift zones. Deep and shallow seismicity indicate a magmatic plumbing system distinct from that of Kilauea volcano. During 1996, a new pit crater was formed at the summit of the volcano, and lava flows were erupted. Continued volcanism is expected to eventually build a new island at Loihi; time estimates for the summit to reach the sea surface range from roughly 10,000 to 100,000 years.