(BIVN) – Kilauea volcano on Hawaiʻi island is not erupting, nor does an eruption appear imminent. However, on Thursday evening, the USGS Hawaiian Volcano Observatory issued an information statement explaining the recent ground deformation patterns observed on the middle East Rift Zone. 

“Elevated rates of ground deformation in Kīlauea’s middle East Rift Zone continue following the June 22–25 upper East Rift Zone intrusion within Hawaiʻi Volcanoes National Park,” the USGS HVO wrote. “These observations indicate that magma is accumulating beneath the ground in the area of Makaopuhi Crater and Napau Crater, a well-known magma storage region on Kīlauea’s remote middle East Rift Zone.”

The USGS Volcano Alert Level remains at ADVISORY / YELLOW.

The USGS HVO wrote the following:

RECENT ACTIVITY

Between July 22–25, 2024, several pulses of strong seismicity and correlated ground deformation indicated that magma was intruding into the upper East Rift Zone (UERZ) of Kīlauea. More than 1,700 earthquakes occurred during this intrusion, along with changes in ground deformation patterns—Kīlauea’s summit region deflated as magma moved underground into the UERZ, where inflation indicated magma was accumulating near Pauahi Crater.  

During the intrusion, some earthquakes were located in the upper Middle East Rift Zone (MERZ) past Maunaulu to Makaopuhi Crater. Beginning on July 23, ground deformation patterns in the MERZ began to show extension and uplift. Over the past week, extension and uplift has continued but the rates have slowed over time. In total, the area across Makaopuhi Crater has extended approximately 12.5 cm (5 inches) and uplifted about 7 cm (2.8 inches) since July 23. Starting on August 8, the POC tiltmeter located on the north flank of Puʻuʻōʻō in the middle East Rift Zone also began to showed movement consistent with the ongoing MERZ inflation. Ground deformation signals recorded by POC and nearby GPS stations indicate the center of deformation remains west of Puʻuʻōʻō. 

Earthquakes have also continued to occur in the UERZ and MERZ since the July 22–25 intrusion. In the UERZ, around 70 events have occurred per day on average, while in the MERZ, around 25 events have occurred per day on average. Most events have been smaller than magnitude-2 and located 2.5–3.5 km (1.5–2.2 miles) beneath the ground surface.

At Kīlauea’s summit, earthquake activity has remained low following the UERZ intrusion, while ground deformation patterns have shown steady inflation since July 26.

USGS: “This map shows recent deformation at Kīlauea, over the timeframe of July 26-August 7, 2024. Data were acquired by the European Space Agency’s Sentinel-1A satellite. Colored fringes denote areas of ground deformation, with more fringes indicating more deformation. Each color cycle represents 2.8 cm (1.1 in) of ground motion. The round feature east of Makaopuhi Crater on the East Rift Zone indicates inflation over this time period due to magma accumulation underground. Arrow in the upper left indicates satellite orbit direction (arrow) and look direction (bar).”

INTERPRETATION

Current ground deformation patterns suggest that a magma pathway between the UERZ and upper MERZ has been reestablished and that new magma is being supplied to the storage region near Makaopuhi Crater following the July 22-25 intrusion. This new magma is likely sourced from the recent intrusion but could also have a component from the summit as well. In either case, the rate of ground deformation indicates the rate of magma supply has decreased over the past two weeks and continues to decrease. Future episodes of unrest in this region could lead to additional intrusions and/or eruptions.

These recent changes indicate that magma is re-pressurizing Kīlauea’s summit storage regions while also refilling a long-lived storage region near Makaopuhi Crater on the MERZ. Pulses of magma storage have been previously recorded in the region of Makaopuhi Crater, as have eruptions. Several eruptions in this area during the 1960s–1970s lasted from less than one day to about two weeks, with long-lived eruptions nearby at Maunaulu (1969–1971, 1972–1974) and Puʻuʻōʻō (1983–2018). Magma was also stored in the Makaopuhi Crater area in 1997 and 2007, during the long-lived Puʻuʻōʻō eruption nearby.

USGS: “This reference map depicts the features on Kīlauea’s middle East Rift Zone, much of which is within Hawaiʻi Volcanoes National Park. Pit craters and lava flows are evidence of a long history of magma moving along this rift zone pathway. Numerous eruptions took place in this region during the 1960s–1970s. Most eruptions in this area during that timeframe lasted less than one day to about two weeks, though there were long-lived eruptions at Maunaulu (1969–1971 and 1972–1974) and Puʻuʻōʻō (1983–2018). The most recent eruption in this area took place over 35 years at and near the Puʻuʻōʻō vent (shown in orange on the map).”

Recent unrest has been restricted to Kīlauea’s upper and middle East Rift Zone within Hawai’i Volcanoes National Park; no unusual activity has been noted east of Puʻuʻōʻō, along Kīlauea’s lower East Rift Zone, or in the Southwest Rift Zone at this time.

WHAT WE CAN EXPECT  

It is not possible to forecast an exact outcome of this activity but some potential scenarios, based on past events, are described below. Future intrusions and eruptions are possible along the upper and middle portions of Kīlauea’s East Rift Zone. Recent Kīlauea eruptions have occurred with as little as 1 hour or less of advanced warning in the form of accelerated rates of ground deformation and earthquakes.  

Here are some possible scenarios that could play out in the coming days to weeks:    

No eruption: Magma accumulation continues to slow or stop below the surface near Makaopuhi Crater and does not result in an eruption.

Upper to Middle East Rift Zone intrusion or eruption: New pulses of magma could be transferred from the summit to the MERZ below the surface to the area from Maunaulu to Napau Crater, leading to an intrusion or eruption in the upper to middle East Rift Zone within Hawai’i Volcanoes National Park. In this scenario, we would expect to see increased rates of earthquakes in the upper to middle East Rift Zone along with ground deformation and summit deflation before lava reached the surface.

Summit eruption: It is possible that an eruption could occur in the summit region. In this scenario, we would expect to see increased rates of seismicity and ground deformation in the summit region before lava reached the surface.

Eastward magma migration: New pulses of magma could continue to accumulate below the surface near Makaopuhi Crater and migrate eastward toward and possibly beyond Puʻuʻōʻō. In this scenario, we would expect to see earthquake locations and ground deformation patterns start to occur further east than they are now. This scenario is less likely than the above scenarios based on current activity.

WHAT WE ARE DOING       

Kīlauea’s middle East Rift Zone is monitored with a dense network of instruments recording seismic activity, ground deformation, and volcanic gas emissions. Several webcameras also provide views of this remote area within Hawai‘i Volcanoes National Park.

HVO staff conducted an aerial overflight of Kīlaueaʻs middle East Rift Zone on August 1 and did not observe any new cracks or thermal areas. Another HVO reconnaissance overflight is planned for next week. HVO is in frequent communication with Hawai‘i Volcanoes National Park and Hawai‘i County Civil Defense to keep them apprised of Kīlauea activity.

HVO continues to closely monitor Kīlauea, watching for any signs of unrest that may precede a new eruption. Should volcanic activity change significantly, a Volcanic Activity Notice will be issued.