Earthquakes don鈥檛 just shake the ground, they can also shift rivers, damage stop banks and raise the risk of flooding for years afterwards.
Te Whare W膩nanga o Waitaha | 茄子视频app官网 PhD student Erin McEwan has created the world鈥檚 first database tracking how earthquakes have changed rivers and flood protection in the past. Her research could give councils and emergency planners new tools to prepare communities for future disasters.
鈥淭his is a hazard that hasn鈥檛 had much attention before,鈥 McEwan says. 鈥淏ut in New Zealand, where we have thousands of rivers and lots of active fault lines, it鈥檚 inevitable that they will intersect and interact.鈥
Understanding the risks
Over 3,700 rivers in Aotearoa could be at risk of earthquake-related flooding if the fault lines beneath them rupture. More than 450 of these are as large as Canterbury鈥檚 Hororata River.
When quakes hit, rivers may shift course, flood, or become blocked entirely, sometimes creating permanent dams and lakes. The 1987 Edgecumbe earthquake, for example, damaged stop banks and altered the Rangitaiki River floodplain. The region has faced major floods since, including the 2017 event that forced 3,000 people to evacuate.
Other quakes, such as those in Christchurch and Kaik艒ura, also reshaped how water moves across the land, redrawing flood maps and exposing new areas to risk.
Global science, local impact
McEwan鈥檚 study combined data from 52 international earthquakes with New Zealand鈥檚 fault maps and flood models to test future scenarios.
鈥淚f this method was used across New Zealand, it could help communities build more earthquake-resilient flood risk planning,鈥 she says.
Her goal is to get the findings into the hands of councils and planners, so they can run their own 鈥渨hat if鈥 scenarios when making decisions about homes, infrastructure and land use.
Supporting smarter planning
McEwan鈥檚 work was supported by a Natural Hazards Commission Toka T奴 Ake (NHC) grant awarded to her UC supervisor, Dr Timothy Stahl.
Dr Natalie Balfour, NHC Head of Research, says the project highlights how earthquake risk extends beyond shaking.听
鈥淔rom a planning perspective, knowing where flooding is more likely after a quake gives us a powerful new tool to protect people and properties,鈥 she says.
For McEwan, the message is clear: 鈥淲e can鈥檛 stop earthquakes or floods, but we can help people be ready for them.鈥
