The sequence began on September 1, 1596, when the Keicho-Iyo earthquake ruptured the Japan Median Tectonic Line in western Shikoku, breaking the Kawakami and Iyo faults. Within hours or days -- historical records disagree on the exact timing -- the Keicho-Bungo earthquake struck around Beppu Bay, triggering tsunamis along the coast. Then on September 5, the largest shock hit: the Keicho-Fushimi earthquake, centered in the Kansai region near Kyoto. Modern seismologists attribute this domino-like pattern to Coulomb stress transfer, where the rupture of one fault segment increases stress on adjacent segments, triggering them in sequence. The three earthquakes tore along roughly 300 kilometers of the Median Tectonic Line, one of Japan's longest and most active fault zones, running parallel to the Nankai Trough.

The earthquake devastated Kyoto and the surrounding region, killing over 1,200 people. Fushimi Castle, which Hideyoshi had built between 1592 and 1594 as his retirement residence, was reduced to rubble just two years after its completion. The destruction of the Daibutsu at Hoko-ji was especially galling to Hideyoshi. Historians believe the warlord had commissioned the Great Buddha not as an act of devotion but as a display of political power. When the statue crumbled, it undermined the very image Hideyoshi had spent years constructing. He reportedly cursed the Buddha, and his arrow into the statue's face was a gesture of contempt rather than grief. The ruined figure stood in its wreckage until 1597, when Hideyoshi ordered it demolished. After Hideyoshi's death in 1598, his son Toyotomi Hideyori undertook the reconstruction of the Daibutsu, though it would face further destruction by fire in years to come. Hideyoshi himself relocated Fushimi Castle to a nearby hill called Kohatayama and rebuilt it.

The 1596 earthquake left physical evidence that modern geologists have been tracing ever since, particularly after the devastating Great Hanshin earthquake of 1995 renewed interest in the region's fault systems. Paleoseismological studies on the Japan Median Tectonic Line and the Arima-Takatsuki-Rokko-Awaji Fault have identified a surface rupture associated with the 1596 event along the Gosukebashi Fault on the eastern side of Mount Rokko. Evidence for soil liquefaction was uncovered in Yawata, Kobe, and Amagasaki. Landslides were triggered at the ancient Imashirozuka Kofun burial mound in Takatsuki and in Nada-ku, Kobe. Radiocarbon dating of paleoseismic events on these faults has revealed a pattern of major earthquakes stretching back thousands of years, with recurrence intervals of up to 3,000 years -- making the 1596 event only the most recent chapter in a seismic story that extends to the earliest recorded earthquake in Japanese history, the 416 AD Yamato earthquake.

The Japan Median Tectonic Line is among the longest fault zones in the country, running parallel to the Nankai Trough where the Philippine Sea Plate dives beneath Honshu. Four tectonic plates converge in this region -- the Pacific, Amurian, Philippine Sea, and Okhotsk -- making southwestern Japan one of the most seismically complex places on Earth. The 1596 sequence demonstrated that the MTL can rupture in cascading segments across hundreds of kilometers. Further studies have identified additional faults on Awaji Island, including the Naruto Fault, that also ruptured during the same period. The Ikeda Fault on Shikoku shows evidence of right-lateral and vertical displacement that may correspond to the 1596 event. With recurrence intervals of up to 3,000 years along some segments, the long silence since 1596 on the Gosukebashi Fault does not mean safety. It means the clock is still running.