Hawaiian Volcano Update: Intrusion Ongoing SSW of Kīlauea Caldera

Now one full month since its most recent summit eruption, Kīlauea's unrest continues after earthquakes began to escalate last week. While seismic rates have decreased, they are still significantly above background levels, and the ground continues to deform especially centered in the area south-southwest of the modern caldera. Satellite measurements show a broad area of uplift that accompanies an intrusion of magma southwest of the summit, which can also be observed on ground tilt and GPS stations nearby.

While similar previous patterns have rarely led to eruptions in that area, the high rates of ground movement suggest that a strong burst of seismicity to the surface could potentially initiate an eruption with little notice according to the USGS HVO. Gas emissions remain at background levels for the volcano around 100 tonnes of SO2 per day, but can still affect sensitive individuals in downwind areas. Typically gas emissions are at their worst at the start of each eruption, thus now is the best time for those exposed to prepare.

A possible recent shift of the inflation center away from Halemaʻumaʻu south to this area may have been aided by the movement of blocks within the caldera at the start of last month's eruption. This would continue the pattern of adjustments away from the Upper East Rift Connector and towards the Southwest Rift Connector, which involves bridging movements on the Koaʻe Fault Zone. The current seismicity, near the vents for the December 1974 eruption, borders the fault zone that enabled that eruption to break out, but examining the historical pattern of earthquakes, clear differences can be seen between then and now. We review these changes through maps and scientific literature to offer further insight this week.

Of course as usual we step through the monitoring signals, imagery and reports available courtesy of the USGS Hawaiian Volcano Observatory, annotating the presentation on screen and discussing live viewer questions as we go.

Maunaloa is still quiet, with deep earthquakes still ocurring over the past week, and expected inflation showing recharge following its 2022 eruption. Following the 1984 eruption, a similar period of inflation without earthquakes lasted about 10 years. Any sign of renewed activity of Maunaloa will eventually occur in the context of this post-eruptive background trend.