| A.D. | Era | Level of Eruption | Special Note |
| 1611 | Year 16 of Keicho | Unknown | As no detailed data on the incident remains, the occurrence of eruption is in question. |
| 1638 | Year 5 of Kanei | Unknown | Same as above |
| 1663 | Year 3 of Kanbun | Eruption occurred at the summit | Five casualties resulted, and it happened during the reign of the 4th Tokugawa Shogun, Ietsuna. |
| 1769 | Year 5 of Meiwa | Eruption occurred at the summit | Occurred during the reign of the 10th Tokugawa Shogun, Ieharu. |
| 1822 | Year 5 of Bunsei | Eruption occurred at the summit | 82 casualties resulted, and it occurred during the reign of the 11th Tokugawa Shogun, Ienari. A British ship arrived in Uraga in the same year. |
| 1853 | Year 6 of Kaei | Eruption occurred at the summit | O-Usu (Big Usu) was formed during this eruption. The battle of Tsushima was fought and the famous novel by Natsume Soseki, "I Am a Cat," was written in the same year. |
| 1910 | Year 43 of Meiji | Eruptions occurred at the foot of the mountain | Volcanic smoke rose 700 m high in a mushroom-shaped column during the eruption event, which left behind 36 craters. Meiji Shinzan (Mt. Yosomi) was born. The Japan-Russia Agreement was also concluded this year. |
| 1943 -45 |
Year 18 to 20 of Showa | Eruptions occurred at the foot of the mountain | The second half of World War II until the ceasefire. The area of Fukaba Village experienced massive uplifting at a rate of 60 cm/day as it gradually grew into Mt. Showa Shinzan. Although news of the volcanic event was not widely reported during this critical time in the War, one newspaper article remains that reads: "Volcanic ash which turns into cement when it gets wet is 'War Power' granted to us from Heaven, and it was transported by the army to Okadama airport." When the volcanic smoke mixed with water in clouds, the toxic rain produced reportedly killed many birds which are said to have fallen to the ground. All of the chub and red salmon population in Lake Toya was totally destroyed as well. |
| 1977 | Year 52 of Showa | Eruption occurred at the summit | The volcanic smoke from the eruption reached a maximum height of 12,000 m in the air. Volcanic rocks ejected from Mt. Usuzan struck two window panes on an airplane heading to Nagoya which forced the flight to turn back to Chitose airport in Hokkaido. The amount of ash spewed from the volcano was equivalent to 400 times the volume of Kasumigaseki Building, a massive skyscraper. Motorists driving in the area at the time could see no further than two meters ahead, even with their headlights on during daytime. During the eruption, the Toya-ko Onsen (Lake Toya Hot Spring) area was full of panicked tourists and residents trying to escape. One bus driver was quoted as saying, "I was more afraid of the bus being over-crowded with passengers than the actual eruption itself." Kitanoumi, a Grand Sumo Champion at that time, called home to his mother and father in Sobetsu near Usuzan and said, "Are you all right? Get out of there as quickly as possible." Meanwhile in one heartwarming story, a doctor and a nurse successfully assisted a pregnant woman in giving birth in a car during the evacuation. The amount of damage caused by the eruption totaled 31.6 billion yen. The main centerfold section of the August 28th issue of Myojo magazine, which reported the eruption, featured stories on Japanese pop culture from the time such as the wedding of Takuro Yoshida and Miyoko Asada, the vocal group Karyudo, 18-year-old singer Hiromi Iwasaki, and the engagement of Kinya Kitaoji. |
| 2000 | Year 12 of Heisei | Eruptions occurred at the foot of the mountain | Only 23 years after the previous event, another eruption occurred at the base of the Mt. Nishiyama area on the southwest section of Mt. Usuzan. It happened in the early morning hours of March 31, as a number of townspeople and members of the media watched on. Volcanic earthquake signals had been recorded at dawn on March 27, just three days earlier. Fortunately, there were no casualties since residents in the surrounding towns of Abuta-cho, Sobetsu-cho and Date-cho had been completely evacuated. On April 1, a new crater opened up and was formed at Konpira-Yama behind the town of Toya-ko Onsen; eventually the number of craters would total over 50. The eruption pattern was marked by shifting crater locations, and it closely resembled the eruption that occurred in 1910. Mt. Usuzan, which has erupted four times over the past 100 years, makes us aware of the awesome power and destructive force that an active volcano possesses as well as the need to be prepared for future volcanic events. |