Rare in situ pore pressure and temperature data sets collected over more than one decade in a submarine landslide‐prone area off Nice (Southeast France) have been used to characterize a transient groundwater exchange between a coastal confined aquifer and the nearshore shallow‐water submarine shelf. The near‐coast study zone is highly exposed to geohazards and remains sadly famous for the 1979 catastrophic tsunamigenic submarine landslide with several casualties and substantial material damage. Measured pore pressure buildup does not appear to be synchronized with either the discharge of the nearby Var River or with precipitation in the Nice area. Unexpectedly, pore pressure fluctuations synchronizes well with seabed temperature trends indicating that the nearshore submarine shelf is mainly impacted by long smooth seasonal variations. We used the pore pressure and temperature data to describe the general transport mechanisms of pore waters and show that pore pressure diffusion is predominantly responsible for the near‐seabed pore pressure buildup. Based on our results and previously published geotechnical data, slope stability calculations reveal that groundwater exchange has a major impact on slope instability and shear zone formation in a prone‐to‐failure area. Minor earthquake‐induced ground accelerations seem to contribute to the nearshore slope instability by decreasing its factor of safety.

中文翻译：

---

通过沿海承压含水层的瞬态地下水流及其对近海海底斜坡失稳的影响

在尼斯（法国东南部）海底滑坡易发地区收集的十多年来稀有的孔隙压力和温度数据集已用于表征沿海密闭含水层和近岸浅水海底架子之间的瞬时地下水交换。该近海岸研究区极易遭受地质灾害的袭击，并以1979年灾难性海啸成因的海底滑坡而闻名，其伤亡惨重，物质损失巨大。测得的孔隙压力累积似乎与附近瓦尔河的排放或尼斯地区的降水没有同步。出乎意料的是，孔隙压力波动与海床温度趋势很好地同步，表明近海海底陆架主要受长期平稳的季节性变化影响。我们用孔隙压力和温度数据描述了孔隙水的一般运移机理，并表明孔隙压力的扩散主要是造成近海床孔隙压力增加的原因。根据我们的研究结果和先前发表的岩土数据，边坡稳定性计算表明，地下水交换对容易发生破坏的地区的边坡失稳和剪切带形成有重大影响。地震引起的轻微地面加速度似乎通过降低其安全系数而加剧了近岸边坡的不稳定性。边坡稳定性计算表明，地下水交换对容易发生破坏的地区的边坡失稳和剪切带形成有重大影响。地震引起的轻微地面加速度似乎通过降低其安全系数而加剧了近岸边坡的不稳定性。边坡稳定性计算表明，地下水交换对容易发生破坏的地区的边坡失稳和剪切带形成有重大影响。地震引起的轻微地面加速度似乎通过降低其安全系数而加剧了近岸边坡的不稳定性。