Volcano Watch Remembers a Special Event: The 2011 Kamoamoa Eruption
The 35-year-long Pu‘u‘ō‘ō eruption on the middle East Rift Zone of Kīlauea was a remarkable opportunity for scientists to improve volcano research and monitoring. Even short-lived episodes in this eruption, like the four-day-long Kamoamoa eruption, offered important insights.
For the 11th anniversary of the Kamoamoa eruption, this week’s “Volcano Watch” is a photo essay that highlights the episode and some of the data collection efforts.
In the months leading up to the Kamoamoa eruption, lava filled Pu‘u‘ō‘ō crater. Steady inflation was recorded at Kīlauea’s summit and the middle East Rift Zone. As the system pressurized, seismicity increased in the upper East Rift Zone and the summit lava lake rose to the highest levels recorded before that time.
On March 5, 2011, seismic tremor and increased earthquake activity, accompanied by rapid deflation at Pu‘u‘ō‘ō, began abruptly at 1:42 p.m. An intrusion uprift drew magma away from beneath Pu‘u‘ō‘ō. Shortly after, the Pu‘u‘ō‘ō crater floor began to subside and the summit lava lake level dropped.
The USGS Hawaiian Volcano Observatory (HVO), alerted by near real-time seismic alarms and deformation data, quickly conducted an overflight of the area and witnessed the start of the Kamoamoa eruption at 5:09 p.m. between Pu‘u‘ō‘ō and Nāpau craters.
In the first few days, eruptive activity shifted around two fissure systems with vents repeatedly starting and stopping. Early on March 8, the eruption focused on the two opposite ends of the fissures. The activity waned in the afternoon of March 9, and around 10:30 p.m. the Kamoamoa eruptive episode was over.
The dike and subsequent eruption acted as a pressure release valve of Kīlauea’s magma plumbing system that had been pressurizing for months. This led to a short-lived eruption hiatus on the East Rift Zone and low lava lake levels at the summit while the system recovered.
During the eruption, to supplement the near real-time data from HVO monitoring stations, scientists also collected lava samples and gas measurements, mapped lava flows and ground cracks, took photos and detailed field notes, along with other tasks. These important data sets help us to better understand volcanic eruptions and their processes.
Analyses of multiple lava samples taken throughout the eruption showed that the erupted lava was initially more evolved than the lava collected on the Pu‘u‘ō‘ō flow fields prior to the Kamoamoa eruption. This means that the dike which fed the eruption either pushed out, or mixed with, a body of cooler magma that had been stored in the rift. As the eruption continued, the lava compositions began to resemble those previously erupted at Pu‘u‘ō‘ō, as “fresher” lava flushed through the system—like what we saw in the beginning of the 2018 lower East Rift Zone eruption.
Studying eruptive episodes on Kīlauea’s East Rift Zone using a multi-disciplinary approach has improved scientific understanding of the volcano. Recognizable precursory changes observed at the summit and Pu‘u‘ō‘ō have helped HVO anticipate new eruptions including Kamoamoa and the 2018 lower East Rift Zone eruption. For over a year, Kīlauea eruptions have been confined to the summit with no indications of magma migration into the East Rift Zone, providing scientists with additional opportunities to learn about the volcano.
Volcano Activity Updates
Kīlauea volcano is erupting. Its USGS Volcano Alert level is at WATCH. Kīlauea updates are issued daily.
Over the past week, lava has continued to erupt from the western vent within Halemaʻumaʻu crater. All lava is confined within Halemaʻumaʻu crater in Hawai‘i Volcanoes National Park. Sulfur dioxide emission rates remain elevated and were last measured at approximately 1,400 tonnes per day (t/d) on March 23. Seismicity is elevated but stable, with few earthquakes and ongoing volcanic tremor. Summit tiltmeters show several deflation and inflation patterns over the past week. For more information on the current eruption of Kīlauea, see here.
Mauna Loa is not erupting and remains at Volcano Alert Level ADVISORY. This alert level does not mean that an eruption is imminent or that progression to an eruption from the current level of unrest is certain. Mauna Loa updates are issued weekly.
This past week, about 55 small-magnitude earthquakes were recorded below the summit and upper elevation flanks of Mauna Loa — the majority of these occurred at shallow depths less than 10 kilometers (6 miles) below sea level. Global Positioning System (GPS) measurements show low rates of ground deformation over the past week. Gas concentrations and fumarole temperatures at both the summit and at Sulphur Cone on the Southwest Rift Zone have remained stable over the past week. Webcams show no changes to the landscape. For more information on current monitoring of Mauna Loa, see here.
Seven earthquakes were reported felt in the Hawaiian Islands during the past week: a M3.1 earthquake 20 km (12 mi) SSE of Waimea at 23 km (14 mi) depth on March 20 at 4:34 p.m. HST, a M2.3 earthquake 19 km (11 mi) SE of Waimea at 24 km (15 mi) depth on March 20 at 11:46 a.m. HST, a M4.5 earthquake 21 km (13 mi) SSE of Waimea at 23 km (14 mi) depth on March 20 at 7:29 a.m. HST, a M2.8 earthquake 8 km (4 mi) E of Pāhala at 32 km (20 mi) depth on March 20 at 6:49 a.m. HST, a M3.5 earthquake 55 km (34 mi) WSW of Captain Cook at 39 km (24 mi) depth on March 19 at 11:51 a.m. HST, a M3.5 earthquake 3 km (2 mi) WSW of Pāhala at 35 km (22 mi) depth on March 19 at 7:22 a.m. HST, and a M3.3 earthquake 8 km (4 mi) E of Pāhala at 30 km (19 mi) depth on March 17 at 11:44 p.m. HST.
HVO continues to closely monitor Kīlauea’s ongoing eruption and Mauna Loa for any signs of increased activity.
Visit HVO’s website for past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake info, and more. Email questions to [email protected].
Volcano Watch is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.