Kīlauea Volcano Alert Level Raised to Watch/Orange After Magma Intrusion
In a recent article by the U.S. Geological Survey Hawaiian Volcano Observatory (HVO), geophysicist Ingrid Johanson provides an update on the recent magma intrusion at Kīlauea volcano. From January 31 to February 3, a significant influx of new magma into Kīlauea’s flank, southwest of the summit caldera, was observed, leading to the raising of the volcano’s alert level to Watch/Orange.
The intrusion was accompanied by hundreds of earthquakes, similar in intensity to those that preceded recent summit eruptions at Kīlauea. This seismic activity prompted HVO staff to raise the alert level at 4:41 a.m. on January 31. However, after the earthquake activity subsided on February 3, the alert level was returned to Advisory/Yellow.
In addition to the seismic activity, high rates of deformation were also recorded during the intrusion. HVO typically monitors changes in deformation using tiltmeters and continuous GPS stations. However, in this case, lucky timing allowed for the acquisition of a special 1-day image pair from the Italian Space Agency’s COSMO-SkyMed satellite. This interferogram, which shows how the ground deformed during the 24-hour period, confirmed that the recent intrusion was larger than previous ones in October 2023 or August 2021.
The interferogram revealed a “classic” dike-opening intrusion pattern, indicating that magma had opened a rectangular, vertically oriented space in the existing rock. The shape of the opening magma body affects the pattern of ground deformation. Similar to opening a bag of chips by pulling on the sides, the ground deforms outward and upward away from the broad sides of the dike, while the ground just outside the dike tip is pulled toward the dike and the ground above is pulled downward.
Interferograms record ground motion by capturing range change between the ground and satellite. The fringes in the interferogram represent motion in the “look direction” of the radar instrument. In this case, the fringes to the southeast showed increasing range change, while the fringes to the northwest canceled each other out somewhat due to a combination of motion increasing range change and upward motion decreasing it.
The interferogram also revealed an area of dense and discontinuous fringes in the middle, which corresponded to the portion of ground that subsided above the dike. This area also exhibited numerous surface cracks, further illustrating the unique way that interferograms capture ground motion via range change.
Overall, the interferogram provided a textbook illustration of deformation from a dike intrusion, a fundamental process for magma migration at volcanoes worldwide. It not only showcased the interesting patterns of rainbow fringes but also highlighted the scientific value of interferograms in understanding volcanic activity.
In terms of volcano activity updates, Kīlauea is currently not erupting, with its alert level at Advisory. Disbursed seismicity continues at Kīlauea’s summit and along the Koa’e fault system southwest of the caldera. Tiltmeters near Sand Hill and Uēkahuna bluff have recorded mild inflationary trends. While periods of increased earthquake activity and ground deformation can be expected to continue in this region, no unusual activity has been noted along the rift zones.
On the other hand, Mauna Loa is also not erupting, with its alert level at Normal. Webcams show no signs of activity, and summit seismicity has remained at low levels. Ground deformation indicates slow inflation as magma replenishes the reservoir system following the 2022 eruption. Sulfur dioxide emission rates are at background levels.
In conclusion, the recent magma intrusion at Kīlauea volcano has sparked interest among scientists at the HVO. The seismic activity and ground deformation observed during the intrusion provide valuable insights into the processes of magma migration and volcanic activity. As HVO continues to closely monitor both Kīlauea and Mauna Loa, further updates will be provided to ensure the safety and understanding of these volcanic systems.