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Volcano Watch: Putting Kilauea’s current activity in perspective

 

Dr. Tom Wright contemplating the new vent within Halemaumau Crater. (Photo courtesy of Hawaiian Volcano Observatory)

Dr. Tom Wright contemplating the new vent within Halemaumau Crater. (Photo courtesy of Hawaiian Volcano Observatory)

(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

Dr. Thomas L. Wright, former scientist-in-charge of HVO, spent the last two weeks in Hawaii exchanging ideas and information with HVO scientists.  

“We’re witnessing a unique time in Kilauea’s history,” Tom says, and he should know. Tom has devoted much of his career to studying Kilauea Volcano and is currently working on an epic project documenting the last 200 years of Kilauea’s volcanic behavior.

Tom’s first “live” eruption, that of Makaopuhi Crater in 1965, formed a lava lake on the east rift zone. When the eruption ended, he took advantage of what he calls a “true outside laboratory” to produce a classic study on the cooling and crystallization of basaltic lava. 

“We started drilling into the lake as soon as the crust was safe to walk on,” Tom recalls, which means there was plenty of red stuff just a few inches beneath their feet.

Tom returned to HVO to serve as scientist-in-charge in 1984, during the Mauna Loa eruption. Upon arriving from the mainland, he immediately donned a flight suit and boarded a helicopter to survey the erupting vents and lava flows. 

After his term was over in 1991, he stayed on at HVO for another two years to continue working with Jane Takahashi on an annotated bibliography and database of papers about Hawaiian volcanism from 1779 to the present. 

Tom’s interest in Hawaiian volcanoes did not wane after leaving the islands. Together with another HVO alumnus, seismologist Fred Klein, he investigated records of earthquakes in Hawaii before the establishment of modern seismic networks. This involved some serious detective work — poring through journals, missionary diaries, newspaper articles, and other hard-to-find references.   

The resulting seismic catalog, along with Tom’s other extensive historical research, laid the foundation for his current project: a 200-year interpretive history of Kilauea Volcano. 

The study involves identifying and interpreting trends and patterns in seismic and deformation data and correlating them with volcanic activity to gain a better understanding of the volcano’s magma supply system. 

The study starts with the first written observations of volcanic activity at Kilauea in 1823. That was a spectacular time to be an observer at Kilauea’s summit. A lava lake covered the entire caldera floor, with multiple vents within the caldera. Tom attributes this high level of summit activity to an extremely rapid rate of magma being supplied to the volcano. 

Another period of high magma influx started in 1907, with renewed filling of Halemaumau Crater, creating another summit lava lake. Lava lake activity ceased completely just before the climactic 1924 explosive eruption. 

Tom reminds us that the 1924 eruption closely followed a large intrusion of magma into the lower east rift zone. The intrusion essentially “emptied” the magma storage reservoirs, starting another cycle of filling and a new eruptive style. 

Over the 200-year history, Tom identifies several such cycles. Detailed investigation of seismic and deformation patterns reveal that major changes in eruptive style are generally a response to increased magma supply to the volcano.

From this long-term perspective, he thinks we may be seeing a new cycle of activity at Kilauea. The increase in magma supply we’ve observed since late 2003, the Father’s Day intrusion, and new eruptive vents on the east rift zone in 2007 are distinctive markers of the transition, leading to the opening of the new vent at the summit. 

Although features of each cycle may be similar, the exact accommodation the volcano makes to the changing conditions varies.  Speaking of the current activity, Tom notes, “We’ve never seen sustained simultaneous eruptions at the summit and on the east rift zone [in the recorded past].” 

Just how the volcano is achieving equilibrium during these past two years of sustained summit and east rift zone eruptions is still a subject of debate.  What is certain is that the long-term context and insights into the internal workings of the volcano provided by Tom’s work adds much fuel and many puzzle pieces to the discussion.

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