A University of Michigan-led team of geologists and engineers is using drones, satellites, helicopters and the human eye to map surface ruptures and some of the tens of thousands of landslides triggered by last month’s magnitude-7.8 earthquake in New Zealand.
Working in collaboration with scientists from New Zealand’s GNS Science and the U.S. Geological Survey, the team will combine observations collected by the technology to create what is expected to be the largest inventory of earthquake-triggered landslides, according to team leader and U-M geologist Marin Clark.
The high-resolution digital topographic maps the will help response teams in New Zealand determine which landslides pose the greatest threat for future sliding and for river damming, which can lead to catastrophic flooding. The project is also viewed as a training exercise for future large earthquakes anticipated in places such as Southern California, the university says in a press release.
The New Zealand quake struck Nov. 13 near the town of Kaikoura on the east coast of the South Island. It killed two people, generated tsunami waves several feet high and stranded hundreds of tourists, who had to be evacuated by helicopter and ship, according to the university.
In addition, it is estimated that 80,000 to 100,000 landslides were triggered by ruptures along at least nine faults. About 150 of the landslides blocked river valleys, and nine are being monitored as potential threats for catastrophic flooding due to river damming.
“If the 100,000 estimate is correct, then this would be the largest documented earthquake-related landsliding event ever – slightly larger than one that occurred in China in 2008,” says Clark, a U-M associate professor of earth and environmental sciences.
Three members of the research team went to New Zealand late last month. They hiked into the affected region with handheld GPS receivers and used helicopter-based observations and drone imagery to map fault ruptures and landslides. They also worked with scientists from GNS Science and the Geotechnical Engineering Extreme Events Reconnaissance Association, a volunteer organization known as GEER.
U-M scientists who made the reconnaissance trip were Adda Athanasopoulos-Zekkos, associate professor of civil and environmental engineering, and postdoctoral researcher Timothy Stahl of the Department of Earth and Environmental Sciences. Clark and team member Dimitrios Zekkos, U-M associate professor of civil and environmental engineering, will travel to New Zealand next month.
The U-M-led team uses small quadcopters fitted with ultra-high-definition cameras to capture extremely detailed video and images of the landslides and surface ruptures, says the university. In addition, satellite imagery will be used to create before-and-after digital elevation models.
“Drones have totally changed how our work is done,” says Zekkos, who also used the drones in Nepal following last year’s magnitude-7.8 earthquake that killed more than 8,000 people and created nearly 25,000 landslides.
“Landslides can block roads, and helicopters are expensive to operate and are often needed for other purposes after a natural disaster,” he adds. “But you can quickly send a drone into places that would otherwise be practically impossible to see – and you can get really, really close.”
On Dec. 8, the team received final approval of funding from the National Science Foundation for the yearlong New Zealand study. The team’s study area spans about 25,000 square miles, covering a region slightly larger than the state of West Virginia.
The project is a collaboration between the U-M and the University of Colorado at Boulder. Clark’s team also includes a collaborator from Greece, John Manousakis.