Researchers develop framework for modeling post-earthquake infrastructure resilience
Oregon State University researchers have developed a computational model for predicting the resilience of local and regional infrastructure networks and the recovery time for affected communities after a massive earthquake and tsunami in the Cascadia Subduction Zone.
The work is important, the researchers note, as some studies predict a 7% to 11% probability of a major earthquake — a “complete rupture” — extending over the next 50 years along the offshore fault, which extends from British Columbia to Northern California.
The new research, led by doctoral student Dylan Sanderson of the College of Engineering, focused on transportation networks, but the model is designed as a framework for use in other types of networks, such as water and electricity networks. The study focused on 18 communities along the Oregon coast, from Astoria-Warrenton to Brookings.
“Our work looks at the connectivity of Oregon communities beyond ‘the really big’ and how long it could take for the transportation network to recover from damage from a Richter-scale earthquake and tsunami,” said study co-author Dan Cox, a professor of civil and structural engineering in the state of Oregon. “We look at connectivity from two perspectives: a local index of intra-community movements and a regional index of community movements. We show that without regional considerations, recovery time can be severely underpredicted.”
The study findings were published in the Infrastructure Systems Magazine.
“Our work is still ongoing, so we haven’t brought our results to the communities yet, but we plan to meet them as a next step,” Cox said.
The Cascadia subduction zone was the site of an earthquake with an estimated magnitude of 9 in 1700 and is building stress where the Juan de Fuca plate slides under the North American plate.
The magnitude of the earthquake is measured on a logarithmic scale of 1 to 10 – each integer represents a 10-fold increase in the measured amplitude and a 31-fold increase in the released energy.
The largest recorded earthquake was a magnitude 9.5 earthquake in Chile in 1960. The 2011 earthquake that resulted in significant damage and radioactive emissions at the Fukushima nuclear power plant in Japan was measured at 9.0.
Sanderson, Cox, Andre Barbosa of the College of Engineering and John Bolte of the College of Agricultural Sciences analyzed the 18 Oregon communities individually and together as a regional network extending about 60 miles east, taking into account factors such as earthquakes, ground shaking, tsunami flooding depth and proximity to airports as well as to highway and bridge maintenance facilities.
“Once we established the regional and local connectivity indices, we examined network health at multiple scales,” Sanderson said. “In some cases, regional recovery is faster than local recovery, such as North Bend and Coos Bay, while in other communities, such as Toledo, local recovery is faster than regional.”
For some communities, such as Rockaway Beach and Lincoln City, the regional and local recovery is predicted to happen at about the same pace, he added.
“Comparing our results with other work that did not take into account the regional network, the recovery time for a single community was found to be four times longer than previously estimated,” Sanderson said.
Communities with rapid regional recovery had access to roads identified as a higher priority for recovery as well as access to roads in areas with smaller hazard intensity measures, the researchers said. Communities that recovered quickly locally did so because of their access to maintenance facilities.
“We’ve shown that adding additional maintenance facilities helped some communities, but others saw little to no improvement in local recovery time,” Sanderson said. “Communities that are more rural saw improvements over time to recover when an additional maintenance facility was added in the region, but communities closer to metropolitan areas experienced only minimal improvement.”
The study highlights some of the differences in the rate of recovery for coastal communities after major disasters and shows that more work is needed to address these issues, the authors said.
“In the short term, the framework could be used to support decision-making by various state or federal agencies, both on a local and regional scale, especially when studying the impact of different policies on increasing community resilience,” said Barbara.
Small cities need a lot of attention for resilience
Dylan Sanderson et al, Modeling regional and local resilience of infrastructure networks after natural hazard disturbances, Infrastructure Systems Magazine (2022). DOI: 10.1061/%28ASCE%29IS.1943-555X.0000694#tabs
Quote: Researchers develop a framework for modeling infrastructure resilience after earthquakes (2022, August 8), retrieved August 8, 2022 from https://phys.org/news/2022-08-framework-post-earthquake-infrastructure- resilience.html
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