Incidents That Define Process SafetyOn page 58, in describing the catastrophic incident in Mexico City, Incidents that Define Process Safety states that the largest explosion was measured at .5 on the Richter Scale by a seismometers that was 20 km away. Since publication, it has been pointed out that some references give 0.5 as the Richter scale value while others give 5. P. 101, the 2nd sentence in the 2nd paragraph should read: "The HF inventory on the Alkylation unit had been transferred into the onsite storage drum as the unit was being prepared for overhaul." On page 314, the date next to the title Exxon Valdez, Alaska is July 10, 1976. It should read March 24, 1989.