Examples of previous dissertations on topics of hazard, risk and resilience. Many other options are possible to suit your interests.
Meteorological and climate change
Flooding
Seismic
Earthquake
Landslides
Tsunami
Wind
Tornadoes
Wild Fires
Glacial-hazards
Nuclear
Subsidence
Fracking & Fossil Fuels
Pollution
Volcanic
Land-cover change
Multi-hazards
Vulnerability and Resilience
Early warning systems
Disaster Risk Management and Mitigation
General Risk Management
Adaptation
Risk Communication
Risk Perception
Participatory Research Methods
Socio-economic
Geo-political
Governance
Activisim
Digital risks
Insurance and capital
Security
Terrorism
Health