Ariake Sea and Amakusa Islands Viewed from Mt. Unzen
Surrounded by the waters on three sides, the mountain trails and roadways on Mt. Unzen afford a panoramas of magnificent views.
The Silhouette of Mt. Unzen Viewed from the Ariake Sea
Additionally, its elegant curved silhouette captures the hearts and minds of those who gaze upon it.
Archipelagic Seascape of Amakusa Matsushima
In the archipelagic Amakusa area, its calm sea and rough cliffs are contrastive, and the eastside area of Kami-shima Island is referred to as "Kankai (ocean view) Alps" for its sharp ridgelines rising from the sea.
Kankai Alps
Shimabara Peninsula with Rising Mt. Unzen (front) and the Amakusa Islands (back)
With Mt. Unzen in its center, Shimabara Peninsula used to be a volcanic island about 400,000 years ago. Approximately 4.3 million years ago, a volcanic island was formed by the eruption of a submarine volcano near Hayasaki, located at the south end of the peninsula and proximate to Amakusa. Subsequently, similar to the Nishino-shima Island of the Ogasawara Islands, the island grew larger by repeated eruptions. Also, about 500,000 years ago, Mt. Unzen (Unzen Volcano) was formed and its eruptive activity began. The eruption products traveled down to connect with mainland Kyushu, forming a peninsula about 400,000 years ago.
Subsequently, an east-west fault separating the Shimabara Peninsula into three areas north and south (Chijiwa Fault) was formed, and although the central part had a structure to allow continuous subsidence as compared to the northern and southern parts (Unzen Graben), the subsequent eruptions concentrated inside the graben. Obama Onsen, Unzen Onsen (Jigoku) and Shimabara Onsen, running east-west, were all formed as a result of volcanic activity in the graben.
Myoken Caldera Resulted from Collapse
While repeating the patterns of eruptions, highly viscous magma spewed forth to create a roundly raised lava dome, and when it could not stand under its own weight, it eventually collapsed as a result of earthquake, etc. finally forming precipitous and magnificent Mt. Unzen .
Tsukumo-jima Islands resulted from the collapse of the Mt. Mayu-yama
Since recorded history, at least three volcanic activities occurred in the area. The eruption of Mt. Fugen that occurred during the Edo era caused the collapse of the Mt. Mayu-yama dome with the loss of 15,000 lives. However, this brought in an abundance of spring water along with excellent fishing grounds and harbors. Although the Heisei eruption of Mt. Fugen that occurred between 1990 and 1995 caused a great deal of damage from pyroclastic flows and debris flows, this eruption created the new highest peak, Mt. Heisei-shinzan (1483 m).
In 2009, the Shimabara Peninsula was approved as the Global Geopark for being a park where visitors can enjoy learning about both sides of the volcanic disaster and subsequent blessings of nature.
The Amakusa area, on the other hand, is considered to have been formed when the geographical stratum that accumulated between about 100 million years ago (Mesozoic Cretaceous period) and about 47 million years ago (Cenozoic Paleogene period) was elevated from the ocean bed. The islands around Goshoura are sites where fossil remains of marine clams and dinosaurs have been discovered, are called dinosaur islands or fossil islands, and in 2009, it was approved as a Japanese Geopark. Also in 2014, the Geopark area was expanded to include the entire Amakusa area in Kumamoto Prefecture to be approved as the Amakusa Geopark.