Not really a surprise, the earth quake swarms over the last few weeks had already elevated the warning & on Wednesday, hours before the eruption, the warning was raised to Orange. On Tuesday they were still at the lower, yet raised levels from the intrusion swarms that subsided Aug 30 when magma intrusion subsided, yet was still ʻon the radarʻ (from what I have noticed...if they mention it, they are still evaluating it):
HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Tuesday, September 28, 2021, 8:04 AM HST (Tuesday, September 28, 2021, 18:04 UTC)
KILAUEA VOLCANO (VNUM #332010)
19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Activity Summary: Kīlauea Volcano is not erupting. Following the recent intrusion of magma beneath the surface in the area south of Kīlauea caldera, which slowed substantially on August 30, earthquake rates and ground deformation in this area have remained near pre-intrusion levels. Other monitoring data streams, including sulfur dioxide emission rates and webcam views, show no significant changes.
Summit Observations: Over the past week, 109 small-magnitude earthquakes—all below M2.5—were detected beneath the summit region of Kīlauea. These earthquakes occurred approximately 1-3 kilometers (0.6-1.9 miles) below ground level near Halema‘uma‘u. There has been no notable seismic activity in the vicinity of the recent intrusion. Since August 30, tiltmeters have not detected any substantial ground deformation in the summit region. These observations suggest that the supply of new magma to the intrusion has stopped. "
& the last of the Wed pre-eruption notices (~ten minutes later the volcano erupted)
"HVO/USGS Volcanic Activity Notice
Volcano: Kilauea (VNUM #332010)
Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: ADVISORY
Current Aviation Color Code: ORANGE
Previous Aviation Color Code: YELLOW
Issued: Wednesday, September 29, 2021, 3:09 PM HST
Source: Hawaiian Volcano Observatory
Notice Number: 2021/H261
Location: N 19 deg 25 min W 155 deg 17 min
Elevation: 4091 ft (1247 m)
Area: Hawaii
Volcanic Activity Summary: Kīlauea volcano is not erupting. Increased earthquake activity and changes in the patterns of ground deformation at Kīlauea’s summit began occurring as of approximately noon on September 29, 2021, indicating movement of magma in the subsurface. At this time, it is not possible to say with certainty if this activity will lead to an eruption -- the activity may remain below ground, as occurred in August 2021 and early December 2020 (two weeks prior to the December 2020 - May 2021 summit eruption), when magma intruded beneath the caldera but did not erupt. However, an eruption in Kilauea’s summit region, within Hawai‘i Volcanoes National Park and away from infrastructure, is one potential outcome.
The US Geological Survey Hawaiian Volcano Observatory is raising the volcano alert level/aviation color code for Kīlauea from Advisory/Yellow to Watch/Orange due to this activity.
HVO will continue to monitor this activity closely and adjust the alert level accordingly.
HVO is in constant communication with Hawai‘i Volcanoes National Park as this situation evolves. The activity is confined entirely within the park. "
HAWAIIAN VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Tuesday, September 28, 2021, 8:04 AM HST (Tuesday, September 28, 2021, 18:04 UTC)
KILAUEA VOLCANO (VNUM #332010)
19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Activity Summary: Kīlauea Volcano is not erupting. Following the recent intrusion of magma beneath the surface in the area south of Kīlauea caldera, which slowed substantially on August 30, earthquake rates and ground deformation in this area have remained near pre-intrusion levels. Other monitoring data streams, including sulfur dioxide emission rates and webcam views, show no significant changes.
Summit Observations: Over the past week, 109 small-magnitude earthquakes—all below M2.5—were detected beneath the summit region of Kīlauea. These earthquakes occurred approximately 1-3 kilometers (0.6-1.9 miles) below ground level near Halema‘uma‘u. There has been no notable seismic activity in the vicinity of the recent intrusion. Since August 30, tiltmeters have not detected any substantial ground deformation in the summit region. These observations suggest that the supply of new magma to the intrusion has stopped. "
& the last of the Wed pre-eruption notices (~ten minutes later the volcano erupted)
"HVO/USGS Volcanic Activity Notice
Volcano: Kilauea (VNUM #332010)
Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: ADVISORY
Current Aviation Color Code: ORANGE
Previous Aviation Color Code: YELLOW
Issued: Wednesday, September 29, 2021, 3:09 PM HST
Source: Hawaiian Volcano Observatory
Notice Number: 2021/H261
Location: N 19 deg 25 min W 155 deg 17 min
Elevation: 4091 ft (1247 m)
Area: Hawaii
Volcanic Activity Summary: Kīlauea volcano is not erupting. Increased earthquake activity and changes in the patterns of ground deformation at Kīlauea’s summit began occurring as of approximately noon on September 29, 2021, indicating movement of magma in the subsurface. At this time, it is not possible to say with certainty if this activity will lead to an eruption -- the activity may remain below ground, as occurred in August 2021 and early December 2020 (two weeks prior to the December 2020 - May 2021 summit eruption), when magma intruded beneath the caldera but did not erupt. However, an eruption in Kilauea’s summit region, within Hawai‘i Volcanoes National Park and away from infrastructure, is one potential outcome.
The US Geological Survey Hawaiian Volcano Observatory is raising the volcano alert level/aviation color code for Kīlauea from Advisory/Yellow to Watch/Orange due to this activity.
HVO will continue to monitor this activity closely and adjust the alert level accordingly.
HVO is in constant communication with Hawai‘i Volcanoes National Park as this situation evolves. The activity is confined entirely within the park. "