Risk assessments for potential glacial lake outburst floods (GLOFs) are primarily focused on large, rapidly expanding lakes. However, the mechanism of cascading hazards that cause small outbursts to transition into big disasters is poorly understood. We investigated the Gongbatongshaco GLOF in the Himalayas, to reveal a novel disaster model and mechanism, considering increasing regional temperature, glacial lake area, and glacial retreat. Global warming drives glacial retreat, and uncover loose sediment that can be mobilized as debris flows, triggering small glacial lake outbursts in high mountain regions. Sediment generated from earthquake-induced landslides exacerbates the flow magnitude in a valley to increase the disaster risk. Concentrations of in-habitants located in these areas are subject to socioeconomic vulnerability, leading to post-disaster poverty within these communities. A reasonable GLOFs resilient mitigation framework is proposed. The results offer new insights into risk assessment, especially for small glacial lakes in tectonically-active high mountain environments influenced by climate change and earthquake activity.