Abstract This paper reviews the variable features of coastal tsunamis caused by offshore active faults along the eastern margin of the Japan Sea (EMJS) based on the historical records and modern observations of earthquakes and tsunamis. Tsunami deposits discovered along the EMJS coast were also introduced and categorized depending on their sedimentary environments. The offshore active faults, which are densely distributed along the EMJS and generate tsunamis, are related to the opening of the Japan Sea back-arc basin during the late Oligocene to Miocene period. The magnitudes of the earthquakes that caused large tsunamis in the EMJS were under 8.0. The size of the fault plane (approximately equal to the tsunami source area) was approximately 10 × 100 and several tens of kilometers in length. The slip distance of the reverse-type faults was less than 20 m. The sedimentary characteristics and depositional processes of tsunami deposits were obtained from deposits in various environments, such as coastal lowlands, marine terraces, coastal lagoons, and inland ponds. Certain unique approaches used to identify tsunami deposits were reviewed, such as gravel layers that intercalate inorganic soils, and a Holocene marine terrace, dinoflagellate cysts, and foraminiferal linings, which are potentially derived from the sea, and chemical features (e.g., the Ca2+/Mg2+ ratio) as indicators of seawater inflow into a coastal lagoon. The spatial distribution and recurrence of earthquakes and tsunamis in the EMJS were found based on previous paleo-tsunami studies. The difference between tsunami deposits caused by offshore active faults and those by megathrust earthquakes only manifests itself in the horizontal and vertical directions, but not in the sedimentary environments and structures. The data thus inferred can be used for the estimation of offshore active fault models and validation of previous tsunami disaster reconstructions in the future.

中文翻译：

---

近海活动断层及其沉积物引起的海啸

摘要 本文根据地震和海啸的历史记录和现代观测，回顾了由日本海东缘近海活动断层（EMJS）引起的沿海海啸的变化特征。还介绍了沿 EMJS 海岸发现的海啸沉积物，并根据其沉积环境进行了分类。近海活动断裂沿EMJS密集分布并产生海啸，与渐新世晚期至中新世日本海弧后盆地的开放有关。在 EMJS 中引起大海啸的地震的震级低于 8.0。断层面的大小（约等于海啸源区）约为10×100，长数十公里。逆向断层滑动距离小于20 m。海啸沉积物的沉积特征和沉积过程是从沿海低地、海洋阶地、沿海泻湖和内陆池塘等各种环境的沉积物中获得的。审查了用于识别海啸沉积物的某些独特方法，例如嵌入无机土壤的砾石层、全新世海洋阶地、甲藻囊肿和有孔虫衬里，它们可能来自海洋，以及化学特征（例如，Ca2+/ Mg2+ 比率）作为海水流入沿海泻湖的指标。EMJS中地震和海啸的空间分布和复发是根据以前的古海啸研究发现的。近海活动断层海啸沉积与超强逆冲地震海啸沉积的差异仅表现在水平和垂直方向，而在沉积环境和构造上并不明显。由此推断的数据可用于海上活动断层模型的估计和未来海啸灾后重建的验证。