Sequence of historical Nankai Trough earthquake events. The map shows the distribution of rupture segments of Nankai Trough earthquakes. Each rupture segment has been broken or unbroken in historical Nankai Trough earthquakes. In the chronological diagram below, horizontal thick lines indicate ruptured segments in each historical event, named after the corresponding Japanese era (shown in the left column). The thick dashed and thin dotted lines indicate segments that are probably and possibly broken, respectively.