The first major earthquake in the sequence struck on August 28, 1916. It registered at magnitude 6.8 — the strongest quake in the entire series — but its hypocentre was relatively deep in the Earth's crust, which limited the surface damage that a shallower event of equal magnitude would have caused. Nantou in 1916 was sparsely populated by the standards of western Taiwan; the mountainous terrain had never supported the dense agricultural settlements of the coastal plains. Damage was recorded across the region, reaching agricultural and forestry industries that the colonial economy depended on, but the loss of life from this initial quake was constrained by both the depth of the event and the sparse settlement patterns of the area. It was a severe opening, but not the most lethal.

The quake that killed the most people came five months later, on January 5, 1917. It registered at magnitude 6.2 on the Richter scale — lower than the August event — but the critical difference was depth. This quake had a shallow hypocentre, meaning the energy released by the rupture had far less distance to travel before reaching the surface. Shallow earthquakes, all else being equal, cause more damage than deep ones of equivalent magnitude; the ground shaking is more intense, more localized, more destructive to structures. Fifty-four people died in this event. They were the people of Nantou's villages and farms — ordinary residents of a mountain region, caught in buildings and on roads that offered no protection against what was happening beneath them. Across the full sequence, the death toll reached 71.

Beyond the two major events, the sequence included dozens of smaller earthquakes that, while not individually devastating, kept the population in a state of prolonged anxiety and prevented full recovery between the larger shocks. This is characteristic of earthquake sequences: the mainshock — or what appears to be the mainshock — is often followed or preceded by events that extend the disruption well beyond a single day. For the people of Nantou in 1916 and 1917, the ground itself had become unreliable. Agricultural work, forestry operations, the ordinary movements of daily life — all of these proceeded against a background of aftershocks and uncertainty. The economic damage reported by colonial authorities included impacts to the farming and forestry industries that the region depended on, though the human cost — displacement, injury, grief, lost livelihoods — is harder to quantify from the records that survive.

The January 5, 1917 earthquake was not contained to Taiwan. Reports described the quake being felt across much of China, with particularly notable effects in Hangzhou, hundreds of kilometers away on the Chinese mainland. This reach across the Taiwan Strait speaks to the scale of the energy released. Taiwan sits at the convergence of the Philippine Sea Plate and the Eurasian Plate — one of the most tectonically dynamic environments in the world. Earthquakes here are not isolated local events but expressions of forces operating across a vast geological system. The colonial seismometers that had been installed in 1898 were recording data that would, over subsequent decades, help scientists understand the specific fault structures beneath central Taiwan. The 1916–1917 sequence was early evidence that Nantou, for all its apparent quiet in the preceding years, sat atop geology that would not stay still.

The seismological record of these earthquakes is part of their historical significance. By 1916, Taiwan had been under Japanese colonial administration for two decades, and the colonial government had invested in scientific monitoring infrastructure as part of its broader administrative apparatus. The instruments in place during the 1916–1917 sequence produced records that contributed to the understanding of seismic activity in the region — the depth of hypocentres, the propagation patterns, the relationship between magnitude and destruction. For the families who lost members in January 1917, this scientific record offers no comfort. Fifty-four people died on a winter morning in the mountains of central Taiwan, their lives ended by forces that the seismometers could measure but not predict and certainly not prevent. The instruments recorded what happened. The people of Nantou lived through it.