Kīlauea quiets after days of unrest

Kīlauea’s upper East Rift Zone unrest has ended after four days of earthquakes.

From Monday to Thursday, there were four strong pulses clustered between Pauahi Crater and Maunaulu, representing stages in emplacement of an intrusive dike beneath this area. The upper East Rift Zone intrusion and unrest had more than 1500 detected earthquakes, including 30 earthquakes magnitude-3 or greater.

The earthquakes and local deformation associated with the first three pulses were consistent with satellite data showing a formation of a shallow 0.5-2 miles dike in this region. Deformation data was consistent with magma slowly moving out of the storage regions of the summit into the dike; deformation data now indicate this magma movement has ended.

The strong pulse of earthquakes Thursday morning was clustered near the intersection of the Chain of Craters and Hilina Pali Roads and was not clearly associated with dike formation. Seismic activity greatly decreased after the end of the fourth pulse and is now back to pre-intrusion levels.

Over the past 24 hours, there were approximately 18 earthquakes detected beneath Kīlauea’s summit, and approximately 300 earthquakes detected beneath the upper East Rift Zone, mostly at depths of 0.0–2.5 miles below the ground surface.

Only approximately 60 earthquakes occurred within the last 8 hours. The fourth pulse ended by midday Thursday. Most events were smaller than magnitude-2, but there were 4 earthquakes magnitude-3 or higher in the upper East Rift Zone.

The fourth pulse of increased seismicity was over by midday Thursday, and overall seismicity rapidly decreased afterward and has now returned to ordinary levels. Additional seismic pulses or swarms may occur with little or no warning and result in either intrusion of magma or eruption of lava.

Tiltmeters in the Kīlauea summit region started recording inflating this morning around 3 a.m., suggesting magma is no longer moving into the upper East Rift Zone. Field crews returned to Chain of Crater Road Thursday afternoon and observed new cracks near the intrusion and more deformation of cracks first observed on July 23.

Rates of seismicity and ground deformation beneath the middle and lower East Rift Zone and lower Southwest Rift Zone remain low. Recent eruptive activity and ongoing unrest have been restricted to the summit and upper rift zone regions.

Additional seismic pulses or swarms may occur with little or no warning and result in either continued intrusion of magma or eruption of lava. Changes in the character and location of unrest can occur quickly, as can the potential for eruption, but there are no signs of an imminent eruption at this time.

A summary of the first three pulses of intense seismicity activity is provide in an information statement published on July 24.