Warning times vary for different sites, and those with stronger shaking levels tend to receive shorter warning times. Here, lines show the distribution of warning times for sites with different observed maximum shaking levels. Of the sites that experience an MMI of 4.0 (blue lines) — which feels like a truck hitting a building— more than 80% will receive an alert five seconds or more before shaking starts. For the sites with much stronger shaking of MMI greater than 7.0 (yellow lines), where shaking will topple furniture and fixtures, about 50% of sites will receive an alert with at least five seconds of warning time. Credit: Men-Andrin Meier