Hawaiian volcano eruption in 2018 was triggered by sustained rainfall

Eruption of Hawaii’s Kīlauea volcano in 2018 was triggered by heavy RAINFALL, study shows

  • The May 2018 eruption was likely caused by extreme rainfall in the months prior
  • US geologists say this was caused by wet volcanic rock breaking under pressure
  • Higher rates of rainfall caused by climate change could lead to more eruptions 

Excessive and sustained rainfall caused the massive eruption of the Kīlauea volcano in Hawaii two years ago by softening the rock, according to a new study.

US researchers say the dramatic eruption in 2018, which destroyed hundreds of homes, was due to wet volcanic rock, which breaks easily under pressure.

Local rainfall patterns contributed to the timing and frequency of the chaotic eruption at Kīlauea and perhaps at other volcanoes, they say. 

Increased levels of rainfall caused by climate change could also mean more dramatic volcanic events in the future, not just in Hawaii, they warn. 

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Lava erupts from a fissure east of the Leilani Estates subdivision during ongoing eruptions of the Kilauea Volcano in Hawaii, US, May 13, 2018. UM Rosenstiel School scientists have showed that the eruption was likely initiated by prolonged, and at times extreme, rainfall in the months leading up to the event

Outbreaks of lava fountains up to 300 feet (90 metres) high caused hundreds of homes to be lost in the Puna district on Hawaii’s biggest island

‘Interestingly, when we investigate Kīlauea’s historical eruption record, we see that magmatic intrusions and recorded eruptions are almost twice as likely to occur during the wettest parts of the year,’ said Dr Jamie Farquharson at the Rosenstiel School of Marine and Atmospheric Science, University of Miami. 


The Kilauea volcano on Hawaii’s Big Island has been erupting for more than 30 years but bubbled up in May 2018 after the volcano’s summit rose in the weeks leading up.

In years prior the volcano has mostly released lava in hard-to-reach areas inside a national park or along the island’s coastline. 

Lava from the bubbling volcano has now destroyed over 600 homes and forced nearly 2,000 residents to evacuate.

Researchers that tracked the event said there was no indication when the destructive lava flow would come to a halt.

By early August the eruption had almost completely subsided, and on December 5, it was declared to have ended after three months of inactivity.  

‘If we can identify regions of the globe where this kind of coupling between rainfall and volcanism exists, it could go a long way towards advanced warning of associated volcanic hazards. 

‘It has been shown that the melting of ice caps in Iceland led to changes of volcanic productivity.

‘As ongoing climate change is predicted to bring about changes in rainfall patterns, we expect that this may similarly influence patterns of volcanic activity.’

The team say the water’s intrusion started in the Pu’O O’o area of the volcano in the east rift zone.

Sustained periods of rainfall trigger volcanic eruptions, because wet rock breaks easier than dry rock when under pressure from the magma below.        

‘We knew that changes in the water content in the Earth’s subsurface can trigger earthquakes and landslides,’ said co-author of the study Falk Amelung, also at the University of Miami.

‘Now we know that it can also trigger volcanic eruptions.’   

The unprecedented eruption of Kīlauea, one of Hawaii’s most active volcanoes, destroyed more than 500 homes.

Although erupting continuously for decades, the 2018 eruption in the Puna district of the state’s largest island entered an extraordinary new phase on May 3, 2018. 

Incandescent lava was shot nearly two hundred feet in the air and spewed over 13 square miles across the well-populated east coast of Hawaii’s biggest island.

The Hawaiian government reported high levels of toxic sulfur dioxide in the area, which affected some of the first responders.

Power lines were reported to have melted off poles because of the heat, with other reports describing streams of lava running through woods and down roads. 

Lava flows at a lava fissure in the aftermath of eruptions from the Kilauea volcano on Hawaii’s Big Island, on May 12, 2018 in Pahoa, Hawaii

To learn more about the cause, using ground-based and satellite measurements of rainfall, researchers modelled the fluid pressure within the volcano’s edifice over time.

Fluid pressure can directly influence the tendency for mechanical failure in the subsurface, ultimately driving volcanic activity.  

‘An eruption happens when the pressure in the magma chamber is high enough to break the surrounding rock and the magma travels to the surface,’ said Professor Amelung. 

‘This pressurisation causes inflation of the ground by tens of centimetres. 

‘As we did not see any significant inflation in the year prior to the eruption we started to think about alternative explanations.’ 

Fluid pressure was the highest in almost half a century prior to the eruption, which likely facilitated magma movement below the volcano.  

While small steam explosions and volcanic earthquakes have been linked to rainfall infiltration at other volcanoes in the past, this is the first time this mechanism has been used to explain deeper magmatic processes.         

The authors have warned that if this process can be detected at Kīlauea, then it is likely to occur elsewhere as well. 

May 12, 2018, the ash plume of Kīlauea is visible drifting across the island as a large bank of rainclouds encroaches on the northern coast

‘Having established the evidence for rainfall-triggered eruptions at Kīlauea, it will be fascinating to investigate other volcanoes,’ said Farquharson. 

The study used Earth-observing satellites and precipitation information from NASA and the Japanese Space Exploration Agency, as well as ground deformation observations from the European Space Agency. 

The findings are published in the journal Nature.


According to Eric Dunham, an associate professor of Stanford University’s School of Earth, energy and Environmental Sciences, ‘Volcanoes are complicated and there is currently no universally applicable means of predicting eruption. In all likelihood, there never will be.’

However, there are indicators of increased volcanic activity, which researchers can use to help predict volcanic eruptions. 

Researchers can track indicators such as: 

  • Volcanic infrasound: When the lava lake rises up in the crater of an open vent volcano, a sign of a potential eruption, the pitch or frequency of the sounds generated by the magma tends to increase.
  • Seismic activity: Ahead of an eruption, seismic activity in the form of small earthquakes and tremors almost always increases as magma moves through the volcano’s ‘plumbing system’.
  • Gas emissions: As magma nears the surface and pressure decreases, gases escape. Sulfur dioxide is one of the main components of volcanic gases, and increasing amounts of it are a sign of increasing amounts of magma near the surface of a volcano. 
  • Ground deformation: Changes to a volcano’s ground surface (volcano deformation) appear as swelling, sinking, or cracking, which can be caused by magma, gas, or other fluids (usually water) moving underground or by movements in the Earth’s crust due to motion along fault lines. Swelling of a volcano cans signal that magma has accumulated near the surface.  

Source: United States Geological Survey

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