In order to characterize students' risk assessment explanations based on the Geohazard Risk Framework, which describes four key elements of risk for high school science education, we investigate whether student explanations include the following risk elements: scientific factors, impacts, human influences, and likelihood. This study uses the Geohazard Risk Framework to analyze how students explain their risk assessments and risk mitigation strategies based on experimentation with an interactive computer simulation designed to model flooding risks and hazards. We analyzed students' explanations using data from 375 students from three suburban, three urban, and three rural schools to learn (1) how secondary students experiment with the simulation and explain flooding risk based on evidence from the simulation and (2) how students carry out and explain model-based testing of a risk mitigation strategy with a simulation. We also analyzed snapshots created by students of the simulation that were used as evidence to support their explanations. Our findings reveal that while the majority of students could identify at least one risk element, those who engaged deeply with the simulation's features demonstrated a sophisticated understanding of the interconnected nature of risk factors. This study underscores the Geohazard Risk Framework's utility in enhancing secondary students' comprehension of flood risks and offers insights into effective simulation-based learning strategies for broader geohazard education.