Hazard risk assessment is essential to coexist with the natural disasters. An open application framework for knowledge-oriented hazard risk assessment based on deeper understanding of the root cause and drivers of a disaster is developed and verified in this study. Hazard risks estimation by numerical simulation could be effective and reliable only if we have enough knowledge and observation data to the hazards. Insufficient knowledge to the natural hazards is the most critical barrier for efficient disaster risk assessment. To transform the knowledge into valuable simulations on hazard risks is still a challenge. To overcome the challenges, we proposed and implemented the application framework for hazard risk evaluation based on deeper understanding approach. For each case study, scientists achieved the accurate simulation processes with best knowledge to the root cause and physical mechanism of the target hazard. Simulation portal was then developed for easier access to the most updated analysis facility. All the data, services, methods and knowledge were compiled into a knowledge base. Those shared data, analysis and simulation facility, knowledge base and value-added services, and the distributed could infrastructure constitute the open application framework. This is a practical framework verified by case studies and will be evolved progressively with more cases of various types of disasters in different places. In this paper, design details of the application framework based on deeper understanding approach and the verification by a case study are explained. The application framework would be a facilitator for capacity building on hazard risk assessment and will be a solid ground for open science development of this domain in the future.