On April 14 and 16, 2016, two consecutive large earthquakes occurred in Kumamoto, Japan. In most countries, it is a common understanding that building structures are designed to resist once to the ground motion from a large earthquake, e.g., one with the intensity level 7 (the highest level on the Japan Meteorological Agency scale; approximately X–XII on the Mercalli scale), during its service life. However, in case of the Kumamoto earth- quakes, a number of buildings were subjected to such large ground motions twice in a few days. This phenomenon was unpredictable, and the authors were convinced during and immediately after the earthquake that the criti- cal excitation method is absolutely necessary for enhancing the earthquake resilience of building structures and engineering systems.