Source of high tsunamis along the southernmost Ryukyu trench inferred from tsunami stratigraphy

作者：Ando Masataka^*; Kitamura Akihisa; Tu Yoko; Ohashi Yoko; Imai Takafumi; Nakamura Mamoru; Ikuta Ryoya; Miyairi Yosuke; Yokoyama Yusuke; Shishikura Masanobu

来源：Tectonophysics, 2018, 722: 265-276.

DOI：10.1016/j.tecto.2017.11.007

• Tsunami deposit
• The 1771 tsunami
• Southernmost Ryukyu subduction
• Recurrence interval
• Tsunami boulder
• Plate coupling

Four paleotsunamis deposits are exposed in a trench on the coastal lowland north of the southern Ryukyu subduction zone trench. Radiocarbon ages on coral and bivalve shells show that the four deposits record tsunamis date from the last 2000 yrs., including a historical tsunami with a maximum run-up of 30 m in 1771, for an average recurrence interval of approximately 600 yrs. Ground fissures in a soil beneath the 1771 tsunami deposit may have been generated by stronger shaking than recorded by historical documents. The repeated occurrence of the paleotsunami deposits supports a tectonic source model on the plate boundary rather than a nontectonic source model, such as submarine landslides. Assuming a thrust model at the subduction zone, the seismic coupling ratio may be as low as 20%.

• 出版日期2018-1-2