Volcano Watch - Seasonal surprises are not only in Santa's realm

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As winter solstice draws near, the seasonal tradition of illuminating this darkest time of year becomes more obvious. Already many homes, shops, and trees are gaily lit with strings of Christmas bulbs, and this past week, Chanukah, the "Festival of Light" began.

An unanticipated display of light was witnessed on the island of Hawaiʻi this past week as well.

Last Sunday evening, December 5, several reports that Mauna Loa was erupting were received by Hawaiʻi Volcanoes National Park and Hawaiʻian Volcano Observatory. Mauna Loa has been featured in the local and national media over the past months and was clearly on everyone's mind.

Recent changes in activity on Mauna Loa signal the likelihood of an eruption in the not-so-distant future; however, such activity does not seem imminent. With the increase in deep earthquakes that began in early July of this year and the swelling of the summit of the volcano over the past two years, the observatory staff has been paying very close attention to each sigh that Mauna Loa produces. Since no increase in activity was observed prior to Sunday's reports, the staff was dubious that Mauna Loa could be erupting.

An HVO geologist investigating the reports along Highway 11 in Ka`u, however, did note an obvious glow—not from Mauna Loa's southwest rift as originally reported, but from its more active neighbor, Kīlauea. More puzzling was the fact that no significant changes in seismicity or tilt signaled an eruption along Kīlauea's southwest rift zone.

The mystery lasted all through the night and wasn't solved until the next morning. The crew on an early helicopter flight confirmed the suspicion that a wild land fire was burning. The "Kipuka Pepeiau Fire" at the 1,680-foot elevation near the southwest rift of Kīlauea has burned more than 650 acres of native and non-native shrubs and grasses. Currently, fire mop-up activities continue, and the Mauna Iki trailhead on Hilina Pali road and Ka`u desert trail on Highway 11 remain closed.

Remarkably, early callers about this event actually reported seeing lava fountains and smelling the strong odor of sulfur. Park Rangers observed an orange wall of light and smoke, which could account for the several reports of a half-mile-long "curtain of fire," implying a fissure eruption was underway. While some consider this an inaccurate description of a line of lava fountains, it turned out to be an accurate description of the Sunday night fire.

Although it may be more difficult to visually identify the source of an orange glow—especially if you are swayed by visions of volcanic eruptions dancing in your head—the smell of sulfur, which would accompany an eruption, is very distinct and can easily be discerned from wild land fire smoke by most noses.

Sulfur dioxide gas is mainly responsible for the strong sulfur smell when Hawaiʻian volcanoes erupt. For many Hawai`i residents, this is also familiar as the pungent, biting aroma of fireworks, or the smell of the matches struck to light them.

For a more direct volcanic field experience, a visit to Halemaumau, Kīlauea's summit crater, will reacquaint your nose with the sharp smell of this aromatic gas. Residents and visitors interested in becoming better acquainted with a variety of volcanic gases may consider attending the "Breath of Kīlauea" fund-raiser to be held early next year by the Friends of Hawaiʻi Volcanoes National Park, www.volcanoseminars.org.

Alert observers are a crucial source of information on an island of over 10,000 square kilometers (4,000 square miles) with three active volcanoes. And while visions of eruptions may be dancing in our heads, it is good for us to pause, take a deep breath, and carefully assess what we are seeing and smelling.

Volcano Activity Update

Eruptive activity at Pu`u `O`o continues. The eruptive activity in the crater of Pu`u `O`o remains weak, with several spatter cones glowing but not doing much else. The PKK flow continues to host scattered breakouts from near the top of Pulama pali to the coastal plain, but the amount of lava visible in these areas has increased in the past week. The ocean entry at Lae`apuki has been inactive since November 27 or 28. However, new PKK surface flows creeping across the coastal plain may reach the ocean in this same area in the next few days.

The active lava on the coastal plain is located about 3.6 km (2.2 mi) from the end of the pavement on Chain of Craters Road in Hawai`i Volcanoes National Park. Expect a 2-hour walk each way and remember to bring lots of water. Stay well back from the sea cliff, regardless of whether there is an active ocean entry or not. Heed the National Park warning signs.

No earthquakes were reported felt on the island during the week ending December 8.

Mauna Loa is not erupting. The summit region continues to inflate slowly. Seismic activity has decreased over the past four weeks after being high for several weeks in early November and generally elevated since July. During the week ending December 8, 17 earthquakes were recorded beneath the summit area. Nearly all are 40 km (23 miles) or deeper and are the long-period type with magnitudes less than 3.