Kīlauea, one of the most active volcanoes on Earth, dominates the southeastern part of the Big Island of Hawaii. It is classified as a shield volcano, characterized by broad, gently sloping sides built up by the continuous flow of fluid, basaltic lava.
The volcano’s persistent activity is deeply woven into the cultural fabric of the Hawaiian people. Ancient Hawaiians revered Kīlauea as the home of Pele, the goddess of fire and volcanoes. The name Kīlauea, meaning “spewing” or “much spreading” in Hawaiian, reflects its frequent and voluminous eruptions.
Understanding Kilauea’s Continuous Activity
The question of how often Kīlauea erupts is complicated because it rarely conforms to the discrete events associated with other volcanic types. Unlike stratovolcanoes, which can remain dormant for centuries between powerful, explosive eruptions, Kīlauea’s activity is typically effusive and measured in sustained periods of lava flow. The geological record shows the volcano is nearly always active somewhere.
Scientists define Kīlauea’s eruptive frequency not by the number of separate events, but by the duration of sustained lava output. Activity generally localizes at two distinct areas: the summit caldera, which contains the Halemaʻumaʻu crater, and the volcano’s two rift zones. The East Rift Zone, in particular, has been a site of decades-long eruptions.
The effusive nature of Kīlauea’s basaltic lava allows it to flow easily over large areas, building the volcano’s characteristic shield shape. This style of eruption can last for years or even decades, as magma is continually supplied from a deep source. While explosive eruptions have occurred in the past, Kīlauea’s modern history is defined by this long-duration lava outpouring.
Patterns of Major Eruptive Periods
Kīlauea’s surface is highly active, with over 90% covered by lava flows less than 1,000 years old. The period from 1952 to 2018 saw the volcano in a state of near-continuous eruption. This era was dominated by activity migrating between the summit and the East Rift Zone.
The most significant event was the Puʻu ʻŌʻō eruption, which began in January 1983 and continued for 35 years until April 2018. Originating in the East Rift Zone, this was the longest and most voluminous rift-zone eruption in over five centuries. It reshaped the landscape, adding new land to the island while destroying hundreds of structures.
The 35-year eruption sequence ended in 2018 when the magma system drained, causing the Puʻu ʻŌʻō vent to collapse and triggering an eruption in the lower East Rift Zone. Simultaneously, the summit of Kīlauea underwent a collapse, enlarging the Halemaʻumaʻu crater and temporarily halting the activity. The volume of magma erupted was roughly equivalent to the volume of the summit collapse, demonstrating the connection between the two areas.
Following this event, Kīlauea entered a brief quiet period until December 2020, when a new eruption began within the enlarged summit crater. The volcano has since settled into a pattern of episodic summit activity. This activity is characterized by short bursts of lava fountaining separated by pauses lasting from days to weeks, as magma pressure builds up beneath the summit.
Current Status and Alert Systems
The United States Geological Survey (USGS), through the Hawaiian Volcano Observatory (HVO), maintains constant surveillance of Kīlauea to monitor its current state and anticipate changes. Monitoring relies on a network of instruments measuring ground movement, seismicity, and gas emissions. Deformation is tracked using tiltmeters and Global Positioning System (GPS) receivers that detect subtle changes in ground elevation, indicating magma accumulation.
Seismometers record earthquakes and volcanic tremor, providing insight into the movement of magma through underground conduits. Scientists also measure the output of volcanic gases, particularly sulfur dioxide (SO2), since changes in emission rates signal a change in the volcano’s internal plumbing system. This data collection allows HVO to communicate the volcano’s status to the public and aviation officials.
HVO utilizes two alert systems to communicate volcanic hazards. The Volcano Alert Level system describes the volcano’s status and associated ground-based hazards using four levels:
- Normal
- Advisory
- Watch
- Warning
Separately, the Aviation Color Code system uses four colors—Green, Yellow, Orange, and Red—to warn the aviation community about potential ash plumes.
Kīlauea is currently in a state of episodic activity, with the Alert Level set to WATCH and the Aviation Color Code at ORANGE. This status indicates that a hazardous eruption is underway, but the activity is confined to the summit area and poses no immediate threat outside of the national park boundaries. Summit inflation recorded by instruments suggests that another fountaining episode is likely in the near future.