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| This first ocean entry of 2012 is already creating a small lava delta, a.k.a. bench, growing the island.. Image: Volcano Discovery. |
November 26, 2012 - HAWAII -
Activity Summary: Eruption continued at two locations: At the summit,
very weak inflation and lava lake level fluctuations continued. At Pu`u
`O`o, glow was generally visible from the usual sources. Lava flows on
the coastal plain were observed entering the ocean yesterday afternoon
and Webcam views show a weak plume this morning. Seismic tremor levels
were low, and gas emissions were elevated.
Recent Observations at Kilauea summit: The summit tiltmeter network recorded continued very weak inflation. The lava lake level slowly fluctuated but there was no net change. The most recent (preliminary) sulfur dioxide emission rate measurement was 600 tonnes/day on November 20, 2012; this value is at the low end of measurements made between rise/fall events but still constitutes a background level of emissions. A very small amount of ash-sized tephra (including fresh spatter bits and Pele's hair) was carried out of the vent in the gas plume and deposited on nearby surfaces. Seismic tremor levels remained steady at low values. Eleven earthquakes were strong enough to be located beneath Kilauea: 1 just east of the summit caldera, 1 within the middle east rift zone, and 9 on south flank faults, including a magnitude-3.8 quake and several aftershocks that occurred yesterday afternoon. The GPS network recorded neither net extension nor contraction across the summit caldera since November 2.
BACKGROUND:
The summit lava lake is deep within an ~160 m (520 ft) diameter
cylindrical vent with nearly vertical sides inset within the east wall
and floor of Halema`uma`u Crater. Its level fluctuates from about 40 m
to more than 200 m (out of sight) below the floor of Halema`uma`u
Crater. The vent has been mostly active since opening with a small
explosive event on March 19, 2008. The surface level of the lava lake
has again dropped below the inner ledge (~31 m or 100 ft below the floor
of Halema`uma`u Crater on October 29, 2012) and has not risen above and
flooded the ledge since October 28. The lake level responds to summit
tilt changes with the lake receding during deflation and rising during
inflation. Recent Observations at the middle east rift zone vents: Lava
flows remained active in two branches on the coastal plain; the eastern
branch was observed entering the ocean yesterday afternoon east of the
easternmost boundary of Hawai`i Volcanoes National Park; a weak wispy
plume is visible from the ocean entry point this morning in one of the
three Webcams with a view of that location suggesting that lava
continued to flow into the ocean overnight. The shorter western branch
was weakly active.Recent Observations at Kilauea summit: The summit tiltmeter network recorded continued very weak inflation. The lava lake level slowly fluctuated but there was no net change. The most recent (preliminary) sulfur dioxide emission rate measurement was 600 tonnes/day on November 20, 2012; this value is at the low end of measurements made between rise/fall events but still constitutes a background level of emissions. A very small amount of ash-sized tephra (including fresh spatter bits and Pele's hair) was carried out of the vent in the gas plume and deposited on nearby surfaces. Seismic tremor levels remained steady at low values. Eleven earthquakes were strong enough to be located beneath Kilauea: 1 just east of the summit caldera, 1 within the middle east rift zone, and 9 on south flank faults, including a magnitude-3.8 quake and several aftershocks that occurred yesterday afternoon. The GPS network recorded neither net extension nor contraction across the summit caldera since November 2.
HAZARD ALERT: Lava entering the ocean builds lava deltas. The lava delta and adjacent areas both inland and out to sea are some of the most hazardous areas on the flow field. Frequent delta/bench collapses give little warning, can produce hot rock falls inland and in the adjacent ocean, and can produce damaging local waves. The steam plume produced by lava entering the ocean contains fine lava fragments and an assortment of acid droplets that can be harmful to your health. The rapidly changing conditions near the ocean entry have been responsible for many injuries and a few deaths. At Pu`u `O`o, glow could be seen from the spatter cone on the north edge and the lava lake at the northeast edge of the crater floor with weaker glow from both sources in the south part of the floor. The tiltmeter on the north flank of Pu`u `O`o cone recorded weak inflation; GPS receivers on opposite sides of the crater recorded neither net extension nor net contraction since late October. Seismic tremor levels near Pu`u `O`o were low and decreasing. The most recent (preliminary) sulfur dioxide emission rate measurement was 300 tonnes/day on November 20, 2012, from all east rift zone sources. - Hawaiian Volcano Observatory / USGS Volcano Hazards Programs.
