August 30, 2021—Summary map of intrusive activity at Kīlauea Volcano―August 23–30, 2021

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Summary map of intrusive activity at Kīlauea Volcano―August 23–30, 2021


Map of volcano summit

This map depicts the detected intrusive activity over the past week at Kīlauea Volcano. The initial swarm of small earthquakes from August 23–25 was centered in the south caldera region, as labelled on the map. A second swarm started late on August 26 in the same area; earthquake counts dropped the following day, but they have remained above background levels and epicenters have shifted further away from the caldera into the Southwest Rift connector. Ground deformation, as measured by tiltmeters and GNSS (GPS) instruments, appears to be focused within the dashed ellipse on the map. The Southwest Rift connector―also labelled on the map―is an underground passageway for magma into the Kīlauea Southwest Rift Zone, and for decades it has been a known source area for seismicity. The connector region is offset to the southeast from the main lineament of eruptive vents marking the Southwest Rift Zone, as evidenced by the 1971 eruptive vents and 1919–1920 Maunaiki lava shield on the map. Eruptions from the connector itself are thought to be rare, though a brief but spectacular eruption occurred in this area on December 31, 1974, producing a lava flow that travelled more than 12 km (7.5 mi) to the southwest.

(Public domain.)