Recent Intrusion and Decreasing Seismicity at Kīlauea Volcano: Update on Magma Activity
Kīlauea, one of the most active volcanoes in the world, has been making headlines lately due to increased seismic activity and a recent intrusion of magma. The United States Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) has been closely monitoring the situation and providing updates on the volcano’s activity.
Last week, HVO scientists noticed an uptick in earthquakes and ground deformation in the region southwest of Kīlauea’s summit. This prompted them to raise the Alert Level/Aviation Color Code for Kīlauea to WATCH/ORANGE on January 31. An intrusive event, where magma breaks rock to create new pathways underground, was underway.
Intrusions are detected through earthquake locations and changes in the ground surface. Earthquake swarms had been occurring intermittently in the south caldera since October 2023, indicating the presence of magma in the area. However, on January 31, earthquake activity significantly increased, with over 700 earthquakes detected throughout the day. Tiltmeters also showed changes in the ground surface, suggesting crack growth that could precede an eruption or intrusion.
HVO seismologists were on high alert, analyzing earthquake locations in real-time. There was a possibility of an eruption at Halemaʻumaʻu, but earthquake locations instead migrated farther southwest along the Koaʻe fault system. By the evening, tiltmeters showed a more consistent deflationary signal, indicating that magma had opened a new pathway and was moving from the storage system below Kīlauea’s summit to the southwest.
Satellite-based InSAR data confirmed these observations. Between January 31 and February 1, Kīlauea’s summit area deflated while the region southwest uplifted and spread apart. A narrow band of subsidence marked where the dike, a vertical sheet of magma, intruded. This intrusion caused surface cracks in loose Keanakākoʻi tephra along the Maunaiki trail near Twin Pit Craters in Hawai‘i Volcanoes National Park.
On February 2, the number of earthquakes began to decrease, along with ground deformation rates. As a result, HVO lowered the Alert Level/Aviation Color Code for Kīlauea back down to ADVISORY/WATCH on February 3. While intrusions have occurred in the south caldera region in the past, this recent intrusion extended farther southwest towards Puʻukoaʻe and the Kamakaiʻa Hills on the Southwest Rift Zone of Kīlauea.
The south caldera area and Koaʻe fault system are significant features of Kīlauea’s surface, but their connections beneath the surface are not well-understood. The recent intrusion highlights the volcano’s activity beneath the surface, serving as a pressure-release valve for the magma reservoir. Although Kīlauea hasn’t erupted since September 2023, it has been very active underground.
As scientists continue to monitor Kīlauea’s activity, they provide valuable insights into the inner workings of volcanoes and help ensure the safety of nearby communities. The recent intrusion serves as a reminder of the dynamic nature of our planet and the ongoing geological processes that shape it.
