Stakeholders in STEM education have called for integrating engineering content knowledge into STEM-content classrooms. To answer the call, stakeholders in science education announced a new framework, Next Generation Science Standards, which focuses on the integration of science and engineering in K-12 science education. However, research indicates many science teachers, particularly those traditionally prepared to teach within a specific science content domain, need to broaden their knowledge in engineering content areas for successful integration. In this regard, researchers have suggested that new integrated STEM curricula should contain a list of key concepts for understanding the specific engineering content area. Therefore, there is a need for generating key concepts in critical engineering areas enabling science teachers to implement engineering into science classrooms. Using a modified Delphi research design, we identified and verified key concepts in earthquake engineering necessary for high school learners to acquire a basic understanding of earthquake engineering. As a result, we created a key concepts list and strand map with 35 key earthquake-engineering concepts. High school science teachers as well as other teachers in STEM content areas can use these key concepts to understand and teach earthquake engineering content in their classrooms.