Time-lapse movie of a research camera positioned northeast of the Fissure 8 cone, looking into the crater. October 11-18, 2018. Images courtesy of USGS/HVO

Time-lapse panorama of the KÄ«lauea Caldera Wide Angle from HVO Observation Tower. October 11-18, 2018. Images courtesy of USGS/HVO

Low sulfur dioxide gas emissions on KÄ«lauea have resulted in greatly diminished vog (volcanic air pollution) in Hawaii, giving rise to spectacular views on the island. Here, looking across the field of lava erupted from KÄ«lauea’s lower East Rift Zone this past summer, the shield-shaped profiles of Mauna Loa (left) and Mauna Kea (right) can be clearly seen in the far distance. Photo taken Wednesday, October 10, 2018 courtesy of U.S. Geological Survey

(Activity updates are written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

KÄ«lauea is not erupting. Summit and East Rift Zone activity are greatly reduced, with low rates of seismicity, deformation, and gas emissions recorded this past week.

Small earthquakes (generally less than magnitude-2.5) continue at KÄ«lauea’s summit. As expected, small aftershocks of the May 4th magnitude-6.9 earthquake continue on the volcano’s south flank.

A slight inflationary trend near and east of Puʻu ʻŌʻō suggests that magma may be refilling the middle East Rift Zone. Low seismicity and reduced gas emissions do not indicate that the magma is shallow, but HVO continues to closely monitor this area and will report any significant changes.

Sulfur dioxide (SO2) emissions across Kīlauea remain drastically reduced, with a combined rate of less than 300 tonnes/day. Small amounts of hydrogen sulfide gas (H2S) are also being released in cooler, wetter volcanic environments, and from decaying vegetation and other organic matter. The human nose is extremely sensitive to the “rotten egg” smell of H2S; some people can detect this gas at less than 0.001 parts per million. Residents have reported smelling H2S downwind of Kīlauea, but these concentrations are well below hazardous levels. More info: ivhhn.org/information#gas.

Hazardous conditions still exist at both the LERZ and summit. Residents in the lower Puna District and Kīlauea summit areas on the Island of Hawaiʻi should stay informed and heed Hawai‘i County Civil Defense closures, warnings, and messages (http://www.hawaiicounty.gov/active-alerts).

The USGS Volcano Alert level for Mauna Loa remains at NORMAL. Since late September, two recurring groups of microearthquakes have been recorded beneath the upper elevations of Mauna Loa Volcano: (1) a shallow cluster between Moku‘āweoweo caldera and the uppermost Southwest Rift Zone, and (2) a slightly deeper cluster centered beneath the upper west flank, roughly 5 to 10 km (3–6 mi) from the summit caldera. The largest of these earthquakes—magnitudes 3.4 and 3.6 on Sept. 30 and Oct. 8—have been in the western cluster. Because there have been no changes in deformation or gas emissions that would indicate shallowing of magma, these microearthquakes do not warrant increased concern about potential eruption. HVO continues to closely watch this seismicity and monitor the volcano for any other changes.

Two earthquakes with three or more felt reports occurred in Hawaii this past week: a magnitude-3.1 quake 16 km (10 mi) southeast of Volcano at 6 km (4 mi) depth 0n Oct. 17 at 1:59 p.m. HST; and a magnitude-3.3 quake 9 km (6 mi) northwest of Volcano at 10 km (6 mi) depth on Oct. 12 at 12:51 a.m.