Hughes wins fellowship for tracking earthquakes

Jun 26, 2003, vol. 27, no. 5
By Carol Thorbes

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Jonathan Hughes' (left) pioneering method of tracking the history of killer earthquakes has made him a respected sleuth in the geological world.

Hughes who graduated from SFU with a doctorate in biological sciences in the fall 2002, is one of 10 scholars who have landed prestigious Mendenhall postdoctoral research fellowhips.

The U.S. Geological Survey (USGS) bestows the award in an effort to attract promising postdoctoral scholars, worldwide, to the organization.

As a research ecologist, Hughes will make nearly $60,000 U.S. annually for two years and receive a $16,000 U.S. grant to track the earthquake histories of numerous faults in Washington state's Puget Sound lowland.

“This kind of work is extremely rewarding,” says Hughes, currently teaching biology at Capilano College. “The ability to identify the recurrence intervals and severity of earthquakes along these surface faults could greatly help people mitigate seismic hazards by showing them where to avoid building or where to bolster emergency preparedness plans.”

The Puget Sound lowland sits at the northern end of the earthquake prone Cascadia region, making its earthquake history a prime concern to urban planners and emergency preparedness officials.

The Cascadia region extends from mid-Vancouver Island to Northern California.

More than four million people, concentrated in Seattle, Tacoma, Everett and Olympia, live in the Puget lowland. Dozens of surface faults, caused by earthquakes, scar the area.

The Seattle fault zone, which runs east/west through the city's downtown core, ruptured 1,100 years ago vertically displacing bedrock seven metres.

“It's a big concern even with relatively small earthquakes - magnitude four or five - along surface ruptures in highly populated areas,” says Hughes. “The potential for damage and loss of life is high because the earthquake breaks the earth's surface.”

What is pioneering about Hughes' Mendenhall proposal is his use of fossil-plants in sag ponds to document earthquake histories.

Sag ponds are wetlands and lakes made by earthquake-induced, land-level changes that typically abut against faults.

Hughes will look for evidence of past earthquakes in sag ponds, found along faults in the Puget lowland.

“For each fault studied, I hope to document the first earthquake since glaciers covered the land some 16,000 years ago. By dating subsequent (younger) earthquakes, I hope to clarify earthquake frequency in the region, which will improve risk assessment.”

During his SFU doctoral research on a gigantic Cascadia earthquake in 1,700 A.D., Hughes established the importance of fossil pollen in identifying earthquakes.

Fossilized pollen and other parts of plants (macrofossils) are specific to pre- and post-earthquake hydrologic (water) conditions.

“Deeper sediments contain older fossils compared with overlying and, thus, younger sediments. If there has been an earthquake then there may be a sudden and dramatic change in found fossil-plants.”

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