Spring 2017

[News]

In New Zealand, Professor Sees Earth’s Immense Power

A magnitude 7.8 earthquake in New Zealand left a section of train track sloped and warped in its wake.

GEOLOGY PROFESSOR MARK HEMPHILL-HALEY went in November to New Zealand to examine the aftermath of a powerful earthquake. What he saw astounded him: trees split in half; a section of train track warped and sloped; and a long fissure across the land.

Professor Mark Hemphill-Haley

Hemphill-Haley’s trip was part of 10-day mission with the National Science Foundation-sponsored Geotechnical Extreme Events Reconnaissance (GEER) Association team to investigate surface faulting from the magnitude 7.8 temblor, and to get a clearer picture of how the earthquake relates to Humboldt County’s geology.

When it comes to earthquakes, he says, Humboldt County and New Zealand’s South Island are similar in geology and level of preparedness. Both regions are in transition zones between large, active plate boundaries. Humboldt County sits in an area called the Mendocino Triple Junction where the San Andreas Fault and Cascadia Subduction Zone converge. New Zealand’s major Alpine Fault and the Hikurangi Subduction Zone meet at the location of the recent earthquake. And like South Island, Humboldt County is not heavily populated, people are more prepared for earthquakes, and many buildings are up to seismic codes.

“We want to know what’s happening in our transition zone and what would happen here if there was an earthquake of that size,” says Hemphill-Haley.

An expert in neotectonics (the study of recent faults), Hemphill-Haley has studied New Zealand earthquakes extensively. He spent much of his 2008 sabbatical studying faulting with New Zealand scientists, and in September 2010, he and Paul Sundberg (’07, Geology; ‘13, Environmental Systems) studied the magnitude 7.1 earthquake near Christchurch, also on South Island.

Six years later, Hemphill-Haley was back in New Zealand after the earthquake that killed two people and caused extensive damage to infrastructure. The temblor struck about 58 miles north of Christchurch and ruptured parts of more than 10 faults extending at least 100 miles to the northwest.

He and his team worked alongside New Zealand scientists who included GNS Science senior scientist Russ van Dissen (’85, Geology). Using 3-D imaging, light detection and ranging technology, and drones to survey the region, they got a close and astonishing look at the damage.

Along the Kekerengu fault, for instance, the quake left an estimated 18-mile-long gash and moved the ground surface sideways by as much as 33 feet in some locations.

“It is always humbling to witness the immense power of the earth—an earthquake is one of the ultimate displays of this power. I’m honored to participate in this reconnaissance, and to work with good friends and associates in New Zealand,” says Hemphill-Haley.

LEARN MORE ABOUT the Geotechnical Extreme Events Reconnaissance Association at geerassociation.org.