Though usually brief, earthquakes are devastating natural disasters, threatening lives and vital infrastructure. The increased risk of their occurrence in global cities underscores the need to integrate seismic mitigation and resilience into sustainable urban planning.

Earthquakes pose complex challenges to urban environments due to their sudden and unpredictable nature. These risks become increasingly difficult to handle as more people flock to the city. World Bank data indicates around 56 per cent of the world’s population now live in urban environments — billions of lives potentially lost or displaced by such events.

Moreover, the destruction of critical infrastructure like hospitals, transportation networks and emergency response centres further delays community recovery. Secondary earthquake effects like tsunamis and landslides compound the devastation, with the total damage costs easily exceeding US$14 billion yearly.

Urban vulnerability factors

Metropolitan areas are particularly vulnerable to seismic hazards due to their unique characteristics. First, the higher concentration of people in cities increases the potential for casualties and property damage during earthquakes. More inhabitants means more lives are impacted, especially in underdeveloped areas.

Poorly designed buildings and inadequate structures are other critical factors that make urban settings susceptible to damage during seismic events. The 1994 Northridge earthquake in Los Angeles highlighted the vulnerability of complex infrastructure, resulting in widespread destruction and loss of life.

Loose soil conditions, insufficient planning, and inadequate emergency response mechanisms round out the factors making cities vulnerable and impeding their ability to mitigate earthquakes effectively. Addressing these exposures at the initial planning stage is key to reducing the impacts of these events and safeguarding lives.

Temblors hinder multiple sustainable development goals (SDG)

Temblors present a direct threat to achieving SDG 11, which aims to make cities inclusive, safe, resilient and sustainable. The destruction of infrastructure undermines efforts to create tenable human settlements, hindering progress toward ensuring access to secure and affordable housing for all.

They can also result in environmental degradation through soil liquefaction, landslides and water source contamination. The reconstruction and recovery efforts post-earthquake may also lead to unsustainable urban sprawl and inadequate land-use planning.

The extensive structural damage, injuries, loss of life and psychological trauma resulting from seismic activities significantly impact SDG 3 – Good health and Well-being. Additionally, earthquakes — though not climate-related — effectively undermine progress in achieving SDG 13 – Climate Action.

Implementing earthquake risk mitigation in urban settings

The imperative for downplaying the impact of seismic events is abundantly clear. Making it happen requires a combination of innovative solutions and improved policy planning.

Base isolation for critical infrastructure

Base isolation systems decouple buildings from the ground motion during an earthquake, reducing the transfer of seismic forces to the structure. This innovation utilises flexible bearings or rubber and lead pads between the foundations and the above architecture. The isolators move and stretch when subjected to pressure, effectively absorbing a significant portion of the tectonic movement during a temblor.

Reducing swaying and shaking enhances overall resilience to seismic events, as recently witnessed during the 2023 Kahramanmaraş Earthquake in Turkey. In 2013, the Health Ministry mandated hospitals with more than 100 beds to feature base isolation technology. This policy turned out to be vital to keeping five healthcare facilities functional during the 2023 event while surrounding structures suffered widespread devastation.

Seismic dampers integration

Specialised devices integrated into building design absorb and dissipate seismic energy to reduce the impact of earthquakes on towering structures. Tuned mass dampers are credited with maintaining the structural integrity of Taiwan’s Taipei 101 skyscraper during the 7.4-magnitude earthquake in April 2024. The massive 660-tonne steel sphere hanging like a pendulum atop the architecture reduced up to 40 per cent of the building’s movement by counteracting its swaying dynamics.

Soil nailing in vulnerable terrains

The combination of sloping ground and loose soil amplifies the risks of property damage, infrastructure failure, and increased hazards to residents in earthquake-prone regions. Soil nailing involves reinforcing soil slopes or retaining walls with closely spaced steel bars or rods to improve ground stability. Launched soil nails are particularly effective for areas with loose sands and soft clays, boasting a 20 per cent higher shear strength than conventional methods.

Several construction projects include soil nailing as a way to stabilise landslide-prone regions. The A40 highway in Gloucestershire currently features rods ranging from about 16 to 24 feet in length to stabilise the area following sustained heavy rainfall.

Land use planning

Implementing rigorous land-use planning regulations can reduce vulnerabilities and enhance the seismic resilience of urban areas. Zoning regulations that consider seismic hazards are crucial. Cities can reduce the potential for catastrophic collapses during earthquakes by restricting high-density development in high-risk areas and enforcing building height limits.

Adopting performance-based design approaches in building codes is equally vital, allowing engineers to tailor structures to meet specific objectives under varying seismic activity levels. The Federal Emergency Management Agency has been fundamental to this development, setting new standards for building repair and new construction.

Enhanced prevention funding allocation

Proactively mitigating temblor hazards means spending more on preventive measures over post-calamity recovery. The United Nations reports a meagre 4 per cent of US$133 billion in disaster-related funding was allocated to risk prevention and reduction in the last decade. The rest was used for cleanups, infrastructure reconstruction, environmental restorations and the like.

While these activities are undoubtedly pertinent, averting natural catastrophes is ultimately more impactful than remediations after the fact. Policymakers must factor this consideration in future urban planning.

Building resilient cities through adequate earthquake preparedness

Innovative technologies, robust planning strategies and community engagement are essential for building resilient cities capable of withstanding seismic events. As urbanisation increases, so does the risk of natural disasters in those regions.

Awareness and implementation of these solutions in the coming years will be vital. These considerations must also become new standards in urban design practices to meet sustainable development goals.