Reducing Extreme Landslide and Seismic Risk in Aizawl
A detailed scenario process engaged leaders and technical professionals in India’s most populous hill city to understand, assess and mitigate Aizawl’s very high risk of landslides and earthquakes.
The Hunthar Landslide
Aizawl, the capital of Mizoram state, faces a high risk of earthquakes from several major active faults. Annual monsoon rain triggers frequent, sometimes deadly landslides. Even a moderate earthquake will unleash hundreds of landslides at once.
The city’s many concrete buildings–up to ten stories tall, built without earthquake-resistant features on landslide-prone slopes–are especially vulnerable to collapse. Poor construction practices and land use exacerbate the hazards.
We helped Aizawl's dedicated planners, engineers and geologists understand why and where residents encounter great risk, to plan for safer development. We teamed them with renowned technical and policy experts from the US and India. They conducted fieldwork to assess building and infrastructure vulnerability, population exposure, geology and landslide hazard.
The team developed a scenario that explains the consequences of a plausible-but-hypothetical magnitude 7 earthquake in Aizawl. Presenting our findings in this format helped policymakers and the public to visualize specific impacts of the risk they face. It's a stark picture: collapse of 13,000 buildings, 1,000 landslides, 25,000 fatalities, and major damage to utilities and infrastructure. More important, though, the report recommends ways to reduce earthquake and landslide risk over time.
Landslides occur frequently in Aizawl, India
The city is on track for a safer future. Here's our role:
Advised the city as it launched the Landslide Policy Committee for Aizawl City--with municipal, state, and technical participants--and created a landslide safety action plan.
Guided the Aizawl Municipal Corporation in writing new site development regulations, which control excavations that can destabilize slopes.
Trained local professionals to implement the new regulations.
Identified and mapped areas of high risk and created landslide hazard maps at 1:5000 scale.
Conducted school earthquake safety programs, and facilitated participation of more than 40 schools in GeoHazards Society’s nationwide school earthquake drill.
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