P outruns S; the S−P lag fixes distance, three circles fix the epicentre
Run this interactive Astronomy & Earth demo live below, or download it as a single self-contained HTML file that works offline in any browser or LMS — one of 1,900+ free interactive teaching demos on Notedeck. With Notedeck you upload your own materials and turn them into interactive courseware, question papers with answer keys, and AI-taught lessons.