Earthquake Risk in Dhaka Under Magnitude 6.5, 7.0, and 8.0 Events
- Mahbub Sumon
- 5 days ago
- 5 min read
A Hypothetical Assessment Based on Population Density, Urban Morphology, and the Status of Green & Blue Infrastructure
Executive Summary
Dhaka, one of the world’s most densely populated megacities, faces severe seismic vulnerability due to its proximity to active tectonic structures, including the Madhupur and Dauki Fault systems. This research presents a hypothetical earthquake-impact analysis for magnitude 6.5, 7.0, and 8.0 events with an assumed epicenter 50 km from Dhaka Zero Point. The study integrates population density, structural fragility, groundwater depletion, and the degradation of green and blue infrastructure to estimate casualties, infrastructural failure, and economic loss. Findings suggest that an 8.0 magnitude earthquake could lead to approximately 180,000 deaths, 870,000 injuries, and economic losses exceeding USD 45 billion. Liquefaction-prone zones particularly areas built on filled wetlands would experience catastrophic structural collapse. Critical transport and healthcare systems would be unable to cope. This study emphasizes the urgent need for seismic building code enforcement, expanded green/open spaces, groundwater management, enhanced trauma-care capacity, and long-term decentralization of Dhaka through satellite cities to build a resilient future.
Introduction
Dhaka, one of the most densely populated megacities in the world, sits perilously close to several active tectonic structures including the Madhupur and Dauki Fault systems. This article presents a hypothetical earthquake-impact analysis for Dhaka at three magnitudes-6.5, 7.0, and 8.0-assuming an epicenter approximately 50 km from Dhaka Zero Point. The projections combine population distribution, structural vulnerability, groundwater depletion, and the shrinking network of green spaces, wetlands, and open fields. This analysis is not a predictive or official hazard forecast. All numbers are order-of-magnitude approximations, intended purely for awareness and planning discourse. Actual outcomes depend on depth, soil conditions, building quality, emergency response capacity, and timing of the event.
Methodology
This assessment integrates:
• JICA-CDMP seismic vulnerability studies
• BUET structural failure analysis
• RAJUK DAP urban morphology datasets
• WorldPop population density maps
• DWASA & WARPO groundwater depletion trends
• Global earthquake casualty estimation models (HAZUS, PAGER, GEM)
Historical megacity earthquakes (Nepal 2015, Kobe 1995, Haiti 2010, Sichuan 2008, Izmir 2020) were used as benchmarks for calibrating casualty and damage ranges. The results represent order-of-magnitude projections, not deterministic forecasts.
Urban Profile of Dhaka
Population & Density
• Greater Dhaka hosts 23–24 million people.
• High-risk inner zones contain ~15 million.
• Density: 23,000–34,000 people/sq km.
• Over 400,000 new residents annually, many in unplanned settlements.
Buildings & Transport
• 300,000–350,000 buildings, many non-code compliant.
• Narrow lanes restrict emergency movement.
• Bridges, flyovers, and metro rail may face 48–120 hours of disruption.
Green Spaces & Wetlands
• 1–1.5 sqm green space per capita vs WHO recommendation of 5–9 sqm. • Wetlands filled in Begunbari, Rampura, Turag, Demra, increasing liquefaction risk.
Groundwater Depletion
•Groundwater levels drop 1.5–3 meters annually.
•Soil weakening increases foundation failure during earthquakes.
Healthcare & Disaster Management
• 0.8–0.9 hospital beds per 1,000 nationally.
• Dhaka has 20–25k total beds-grossly inadequate.
• Communication & utilities may collapse in a major quake.
Seismic Context of Dhaka
JICA and CDMP studies indicate a 7.5+ quake on the Madhupur Fault could severely damage 20–25% of buildings and moderately damage about half. Historical quakes caused less harm as Dhaka was not yet a high-rise megacity; current conditions make past comparisons irrelevant.
Hypothetical Impact Scenarios
The Scenarios
Magnitude | Total Casualties | Deaths | Injured | Trapped |
6.5 | ~75,000 | ~8,000 | ~67,000 | ~15,000 |
7.0 | ~300,000 | ~45,000 | ~255,000 | ~80,000 |
8.0 | ~1,050,000 | ~180,000 | ~870,000 | ~300,000 |
Scenario A - Magnitude 6.5
• 5–7% buildings severely damaged; 15–20% moderately damaged.
• ~8,000 deaths; ~67,000 injured; ~15,000 trapped.
• Economic loss: ~$5 billion (৳60,000 crore).
Scenario B - Magnitude 7.0
• 15% buildings severely damaged; 35–40% moderately damaged.
• ~45,000 deaths; ~255,000 injured; ~80,000 trapped.
• Economic loss: ~$15 billion (৳180,000 crore).
Scenario C - Magnitude 8.0
• 30–35% buildings severely damaged; ~60% moderately damaged.
• Wetland-filled neighborhoods face catastrophic liquefaction.
• ~180,000 deaths; ~870,000 injured; ~300,000 trapped.
• 5+ million homeless.
• ~$45 billion economic loss (৳550,000 crore).
Role of Green, Open & Blue Infrastructure
• Open fields enable evacuation, field hospitals, helicopter access.
• Green spaces stabilize soil, reduce heat, improve resilience.
• Water bodies support drainage and firewater supply; their loss increases liquefaction risk.
Resilient Population Capacity
Dhaka can sustainably support ~12 million people. Current 23–24 million exceeds carrying capacity. Needed: satellite cities, decentralization of offices/industries, expanded public transport, and restored green-blue networks.
Policy Recommendations
• Enforce seismic building codes. • Protect wetlands and increase parks/open fields.
• Expand hospitals and trauma-care.
• Community emergency volunteer programs.
• Groundwater management & rainwater harvesting. • Develop satellite cities.
Conclusion
Dhaka stands at a critical intersection of rapid urbanization, extreme population density, weakened geological conditions, and escalating environmental degradation. This hypothetical assessment of magnitude 6.5, 7.0, and 8.0 earthquake scenarios demonstrates that the city’s vulnerability is not solely a function of seismic hazard, but a compounded outcome of unplanned urban growth, inadequate seismic compliance, groundwater over-extraction, loss of wetlands, and severe shortages in green and open spaces. The projected scale of casualties and economic losses, particularly under a magnitude 8.0 scenario—highlights the fragility of Dhaka’s current urban systems.
A major earthquake in or near Dhaka would not only be a humanitarian catastrophe but also a long-lasting socio-economic shock with national implications. The analysis underscores the urgent need for proactive measures: enforcing seismic building codes, restoring blue–green infrastructure, expanding healthcare and trauma capacity, strengthening community-based disaster response, and pursuing strategic decentralization through well-developed satellite cities. These interventions are not optional—they are essential investments for safeguarding millions of lives.
Dhaka’s resilience will depend on how quickly it can shift from reactive crisis-management to anticipatory, science-driven urban planning. The choices made today will determine whether Dhaka remains critically exposed or evolves into a safer, more adaptive megacity capable of withstanding the seismic risks of the future.
References
JICA & CDMP (2011–2015). Earthquake Vulnerability Assessment of Dhaka.
BUET (IEB & CE Dept.). Seismic Vulnerability Reports.
USGS Seismic Hazard & Tectonic Atlas.
GSHAP Global Seismic Hazard Assessment.
BBS Census 2022.
RAJUK DAP 2022–2035.
WHO Urban Green Space Guidelines.
DWASA & WARPO Groundwater Reports.
UNDRR Disaster Risk Global Assessment.
World Bank Urban Disaster Resilience Study.
FEMA HAZUS Loss Estimation.
GEM Casualty Functions.
Author:
Mahbub Sumon
Electrical and Electronic Engineer
Lead Researcher and Managing Director, Shalbrikkho Ecosystem (Bangladesh)