# Volcano Watch — Dr. George Walker studied nearly every aspect of volcanoes

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Last week, Earth Scientists from all over the world gathered for the annual American Geophysical Union fall meeting in San Francisco. Researchers, including volcanologists, presented the results of their work and gathered to discuss important areas of science.

George P.L. Walker.

(Public domain.)

One of the themes in the volcanological sessions this year was the legacy of George Walker, a world-renowned British volcanologist and former University of Hawaii professor, who died in January 2005.

George Walker authored several hundred papers in volcanology on a broad range of important topics ranging from hazard mitigation, lava flows, and volcanic explosions. Indeed, such was his impact that the majority of volcano scientists refer to some fundamental aspect of his work in almost every piece of research they carry out.

George Walker taught mineralogy, geology, and volcanology at the Imperial College in London from 1951 to 1978, where he revolutionized our understanding of Iceland's geology. He was one of a few foreigners to receive the Icelandic Order of the Falcon (the equivalent of a knighthood), conferred upon him by the president of Iceland in 1977.

In 1978 he accepted a Captain James Cook Research Fellowship from the Royal Society of New Zealand and studied young explosive volcanism of the North Island. Here he greatly advanced understanding of the structure of volcanoes and established new ways to assess volcanic hazards.

He received many awards throughout his illustrious career, including the prestigious Thorarinsson medal from the International Association of Volcanology and Chemistry of the Earth's Interior; the Wollaston Medal, given by the Geological Society of London; the UH Board of Regents Award for Excellence in Research; and the Lyell Medal of the Geological Society of London.

His final academic position was the Gordon Macdonald chair in volcanology at the University of Hawaii, from which he retired in 1996. He authored many of the key papers that mark the rapid evolution of the science of volcanology in recent decades. In Hawaii he spent considerable time at schools and led field trips on geology and volcanoes.

For volcanologists in Hawaii, much of our knowledge of how basaltic volcanoes evolve and how lavas flow is derived from George Walker's work. In 1967 he defined a relationship between the thickness of lava flows and the slope over which they flowed, a relationship ascribed to lava viscosity (a property of lava that describes how fluid it is). In a 1971 research paper, he related lava flux to the formation of simple and compound flow units, complex stacks of cooled lava flows. In a 1973 study, he related the length of lava flows to the average lava eruption rate.

These influential works, which were based on field measurements of lava flows in Hawaii and elsewhere, firmly established the relationship between how lava flow deposits look in the field and how they were emplaced.

While this may seem simple in Hawaii, where we can see lava flows being emplaced on the land surface, imagine trying to work out how an eruption occurred several million years ago, when all you have are some very old, eroded, partly or wholly covered-up, weather-beaten deposits to go on! This is why his work has been widely applied, not only to lava flows on Hawaiʻian Islands, but also in submarine and planetary environments.

Lastly, George Walker is fondly remembered for his self-effacing manner and his dedication to science. Students attending his lectures were intellectually engaged by his eloquence and clarity of thought. In this way, he recruited many of today's volcanologists and shaped the way in which we approach the science.

### Volcano Activity Update

During the past week, the number of earthquakes located beneath Kīlauea remains at levels typical of the current eruption. Inflation continues.

Eruptive activity at Puu Oo continues. On clear nights, glow is visible from several vents within the crater and on the southwest side of the cone. Lava continues to flow through the PKK lava tube from its source on the flank of Puu Oo to the ocean, with a few surface flows breaking out of the tube. In the past week, flows were active on the steep slopes of Pulama pali, above the coastal plain. Surface flows on the pali are visible at night (weather permitting) from the end of Chain of Craters Road.

As of December 15, lava is entering the ocean at East Laeapuki, in Hawaii Volcanoes National Park. A new bench continues to grow in the embayment created during the large bench collapse on November 28. Lava is entering the ocean rather passively, and little glow can be seen at night. Access to the ocean entry and the surrounding area remains closed. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

There was one felt earthquake reported on Hawai`i Island within the past week. A magnitude-3.4 earthquake occurred at 7:49 p.m. on Saturday, December 10, and was located 19 km (12 miles) west of Kailua at a depth of 44 km (28 miles); it was felt in Kailua, Kalaoa, Kamuela/Waimea, Papa Bay, Holualoa, and Captain Cook.

Mauna Loa is not erupting. During the past week, the count of earthquakes located beneath the volcano remains at low levels. Inflation continues but has slowed over the past several weeks.