Kilauea volcano (Hawai'i): HVO monthly update, December 2019

The Hawaiian Volcano Observatory (HVO) note that the rates of seismicity over the month of December 2019 were variable but within long term vales. Sulfur dioxide emission rates were low at the summit and were below detection limits at Puʻu ʻŌʻō and the lower East Rift Zone. The pond at the bottom of Halema'uma'u crater, which began forming on July 25, 2019, continues to slowly expand and deepen. As of early January 2020, the dimensions of the pond are 84 meters by 190 meters (280 feet by 620 feet). Current depth is about 23 meters (75 feet).

Over the past month, about a dozen deflation-inflation (DI) events occurred beneath the summit, similar to the prior month. Since early March 2019, GPS stations and tiltmeters at the Kīlauea summit have recorded deformation consistent with slow magma accumulation within the shallow portion of the Kīlauea summit magma system (1-2 km or approximately 1 mile below ground level). However, HVO gas measurements show continuing low levels of sulfur dioxide, consistent with no significant shallowing of magma. Some amount of sulfur dioxide is being dissolved into the summit lake.

Farther east, GPS stations and tiltmeters continue to show motions consistent with slowed refilling of the deep East Rift Zone magmatic reservoir in the broad region between Puʻu ʻŌʻō and Highway 130. HVO monitoring data do not suggest any imminent change in volcanic hazard for this area. In addition to motion along the East Rift Zone, the south flank of Kīlauea continues to creep seaward at elevated rates following the May 4, 2018 M6.9 earthquake near Kalapana. HVO continues to carefully monitor all data streams along the Kīlauea East Rift Zone and south flank for important changes.

Although not currently erupting, areas of persistently elevated ground temperatures and minor release of gases are still found in the vicinity of the 2018 lower East Rift Zone fissures. These include steam (water), very small amounts of hydrogen sulfide, and carbon dioxide. These conditions are expected to be long-term. Similar conditions following the 1955 eruption continued for years to decades.