UNDERSTANDING AND MANAGING CASCADING DISASTERS
The 2024 Sea of Japan Earthquake
A powerful earthquake of 7.6 magnitude on the Richter Scale struck Japan’s west coast in Ishikawa prefecture on January 1, 2024. The seismic activity killed several people, destroyed buildings, triggered a tsunami and started multiple fires. According to USGS, more than 35 aftershocks that are greater than a magnitude of 2.5 have struck near the epicentre of Japan’s Earthquake in less than 24 hours, see figure below. Of these aftershocks, one was above 6.0, and 12 were 5.0 or above magnitudes. The Japan Meteorological Agency predicts possibility of another earthquake next week, and a 10% to 20% chance that an earthquake of equivalent intensity could occur! Tsunami waves of around 1.2 meters (3.9 feet) were reported in Wajima City, according to Japanese public broadcaster NHK. A large fire broke out in Wajima, destroying over 100 shops and houses. Thus, the main seismic activity is not the only cause of destruction and fatalities. The tsunami and many fire incidents triggered by the main seismic activity exacerbated the damage to infrastructure and loss of life.

What is a cascading disaster?
A cascading disaster is a sequence of events triggered by a primary disaster, amplifying the overall impact. It involves unfolding secondary or tertiary disasters due to the initial event. For example, an earthquake can lead to aftershocks, landslides, tsunamis, or other related hazards, creating a chain reaction of interconnected emergencies. Managing cascading disasters requires comprehensive planning and coordinated response efforts.
What does a cascading disaster look like? Imagine an earthquake scenario. When the ground shakes, the walls of buildings will tremble. Some structures may fall, but some will remain standing. There will be many such walls that are cracked and damaged but don’t fall as the broken parts are carefully stacked over each other. However, in the meanwhile if a gas pipeline ruptures, it ignites a fire and burns down the area. The fire is an interconnected emergency here. This is one of many cascading disasters that will follow an earthquake. When an aftershock hits the area again, all the wobbling walls will collapse, causing more destruction. A smaller magnitude aftershock can often create more damage than the mainshock. The mainshock inducing a sequence of damaging aftershocks is another example of cascading disasters.
An extreme example of cascading disaster is the Tohoku earthquake that struck Japan in 2011. The main earthquake that killed 100 people (disaster 1), lead to a tsunami which killed 19,360 people (disaster 2), which lead to radiation release at a nuclear power plant (disaster 3).
Thus, earthquakes are not the only cause of destruction and fatalities. Cascading disasters such as tsunamis, fires, aftershocks, and liquefaction can exacerbate the destruction of structures, loss of life, disruption of socio-economic activities, and loss of infrastructure. The cascading calamities are often more destructive than the Earthquake itself. Due to the complexity and interdependence of the cascading hazards, a systematic approach to disaster mitigation is essential.
Globalisation and rapid urbanisation has increased interconnectedness of systems and this will only increase the likelihood of cascading disasters, so how can we mitigate this? We need to understand the risks and vulnerabilities, how they interact, and assess how they could lead.
Geospatial technology to reduce cascading risks
Reducing Earthquake cascading disaster risks using geospatial technology involves a combination of risk assessment, early warning systems, infrastructure planning, and community engagement. Here are several ways in which geospatial technology can be applied to minimize the impact of earthquakes and their potential cascading effects:
Hazard Mapping and Risk Assessment
Geospatial data is used to create detailed hazard maps that identify earthquake-prone zones, fault lines, and areas susceptible to liquefaction or landslides. Access to information on the vulnerability, hazard profile and exposure of the area will help assess risk and support decision-making. Analyzing and integrating various layers of spatial information, such as population density, critical infrastructure, and vulnerability assessments, is crucial for developing comprehensive risk assessments.

Early Warning Systems
Geospatial technology can create and enhance early warning systems for earthquakes. Real-time data from seismic sensors, GPS devices, and satellite imagery can be integrated to provide timely alerts to at-risk populations. GIS is used in developing and disseminating GIS-based maps and visualizations that illustrate potential impact areas and evacuation routes in the event of an earthquake.
Infrastructure Resilience Planning
Resilience, in its highest form, entails the elusive ability to prevent disasters from cascading. GIS is utilized to identify and prioritize critical infrastructure, such as hospitals, emergency shelters, and transportation networks, in earthquake-prone areas. After assessing the vulnerability of existing infrastructure to seismic events, the geospatial data can be used to plan and implement upgrades that enhance resilience against earthquake impacts. For example, a study by Sutrisno et al. 2022 in the case of Japan found that dense urban and dense settlement areas with a preponderance of concrete-to-semi-concrete building types, formed on alluvial soil types directly facing the ocean and situated in a flat area are more susceptible to tsunami devastation (see the table for more details).


Community Engagement and Education
Employ geospatial tools to create interactive maps and educational materials that help communities understand earthquake risks and the importance of preparedness. Facilitate community participation through GIS-based platforms, allowing residents to contribute local knowledge and feedback in the development of emergency plans.
Land Use Planning and Zoning
Geospatial technology can guide land use planning and zoning regulations in earthquake-prone regions. It can especially help in identify areas where development should be restricted or subject to specific seismic standards. GIS-based tools can help monitor and enforce building codes and construction practices that reduce earthquake vulnerability.
Simulation and Scenario Modeling
Geospatial technology can be used to create realistic simulation models that depict potential earthquake scenarios and their cascading effects. Scenario modelling exercises help assess the likely impact on infrastructure, population, and emergency response capabilities, helping authorities prepare for different disaster scenarios.
So, in conclusion, look at risks and how they interact with various systems such as the settlements or the buildings and their characteristics. Overall, geospatial technology can enhance the authorities’ ability to understand, monitor, and respond to earthquake risks, thereby reducing the potential for cascading disasters. Combining data-driven decision-making, early warning systems, and community engagement can significantly contribute to building resilience in earthquake-prone regions.
References:
Raduszynski, Théo & Numada, Muneyoshi. (2023). Measure and spatial identification of social vulnerability, exposure and risk to natural hazards in Japan using open data. Scientific Reports. 13. 10.1038/s41598-023-27831-w.
Sutrisno, D., “Cascading disasters triggered by earthquake hazards: An infrastructure resilience approach”, in <i>IOP Conference Series: Earth and Environmental Science</i>, 2022, vol. 1109, no. 1. doi:10.1088/1755-1315/1109/1/012003.