Likelihood of Kīlauea eruption decreases

Activity at the Big Island’s Kīlauea volcano, which is not erupting, has quieted down since Friday and its volcano alert level was lowered from watch to advisory as the likelihood of an eruption has decreased.

The overall decrease in activity since Friday suggests this most recent period of unrest at the volcano is waning; however, renewed activity is possible and an eruption could occur with little advance warning.

According to a Saturday morning update from the Hawaiian Volcano Observatory, seismicity and ground deformation beneath the summit and extending 5 to 7 miles southwest of the caldera under the Koa‘e fault system have decreased significantly during the past day. The intrusion of magma into this area also appears to have slowed.

Earthquake counts dropped from 20 to 30 per hour to 5 to 10 per hour and quakes are no longer clustering in the vicinity of Pu‘ukoa‘e. They are being dispersed more widely from the summit to the southwest. Depths remain consistent, at less than a mile to 2.5 miles below the surface, and magnitudes range from a maximum of 3-plus to less than 1.

In total, less than 300 earthquakes have been recorded in the region during the past 24 hours, reflecting continued decrease in seismic activity.  

Tiltmeters near Sand Hill and Uēkahuna bluff have recorded little change after steep deflation during the past 2 days related to magma moving southwest. GPS instruments have recorded up to 8 inches of horizontal motion at stations throughout the volcano’s Southwest Rift Zone and immediately to the south along the Koa‘e fault zone. 

Patterns of earthquakes and ground deformation indicate magma intruded beneath the south end of the caldera, beginning the morning of Jan. 27. This activity waxed and waned until Jan. 31, when seismicity greatly spiked and tilt indicated a dike was being emplaced, triggering episodic felt earthquakes and rockfalls within Halema‘uma‘u.

A total of more than 3,000 earthquakes were recorded during the past week.

By 5 p.m. Jan. 31, seismicity had migrated southwest of the caldera toward the Ko‘ae fault system and tiltmeters in the south caldera area began to record strong deflation. Modeling of tiltmeter, GPS and satellite radar interferometry images suggest that magma within the initial dike migrated southwest into the new intrusion as it opened beneath the Ko‘ae fault zone.

Seismicity in Kīlauea’s upper East Rift Zone and Southwest Rift Zone remains low. No unusual activity has been noted along the volcano’s middle and lower East Rift Zone sections.

Sulfur dioxide gas emission rates remain low. Field measurements Jan. 17 indicated a rate of about 70 tonnes per day, which was similar to measurements in October, November and early December. Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone — which erupted from 1983-2018 — have been below detection limits for Sulfur dioxide, indicating emissions are negligible.   

While activity has seemingly slowed for now, the situation at Kīlauea remains dynamic. The Hawaiian Volcano Observatory continues to closely monitor the volcano and will re-evaluate alert levels and notices as activity warrants.