On 28 February the Alaska Volcano Observatory (AVO) reported that ongoing unrest at Spurr was characterized by elevated seismicity and continuing deformation. Seismicity remained elevated, though had slightly decreased during the past few days. The seismic network recorded over 70 earthquakes with most located beneath the summit and some located beneath Crater Peak. Inflation continued at a similar rate that has been occurring since early 2024. Minor steam emissions were sometimes observed in webcam images. Weather clouds mostly obscured satellite and webcam views during 1-3 March. The Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale) and the Aviation Color Code remained at Yellow (the second lowest level on a four-color scale).

Geological Summary. Mount Spurr is the closest volcano to Anchorage, Alaska (130 km W) and just NE of Chakachamna Lake. The summit is a large lava dome at the center of a roughly 5-km-wide amphitheater open to the south formed by a late-Pleistocene or early Holocene debris avalanche and associated pyroclastic flows that destroyed an older edifice. The debris avalanche traveled more than 25 km SE, and the resulting deposit contains blocks as large as 100 m in diameter. Several ice-carved post-collapse cones or lava domes are present. The youngest vent, Crater Peak, formed at the southern end of the amphitheater and has been the source of about 40 identified Holocene tephra layers. Eruptions from Crater Peak in 1953 and 1992 deposited ash in Anchorage.

Source: US Geological Survey Alaska Volcano Observatory (AVO)