We estimated the origin time of the 1854 Ansei–Tokai tsunami from the tsunami waveforms recorded at three tide gauge stations (Astoria, San Francisco, and San Diego) on the west coast of North America. The tsunami signal is apparent in the San Francisco and San Diego records, and the arrival time was 0–1 p.m. Greenwich Mean Time (GMT) on 23 December 1854, whereas the tsunami signal of Astoria is ambiguous, and the arrival time could not be determined from the waveform. The simulated waveforms on the basis of nonlinear dispersive wave theory by assuming an origin time of 0 a.m. GMT on 23 December arrived earlier than the observations. Cross‐correlation functions between the observed and simulated waveforms recorded at San Francisco and San Diego showed a time gap between them of approximately 30 min. Based on these results, we concluded that the origin time of the 1854 Ansei–Tokai tsunami was approximately 00:30 a.m. GMT or 09:46 local time on 23 December. Our result is roughly consistent with reports by a Russian frigate anchored in Shimoda Bay, ranging the earthquake between 09:00 and 09:45 and the tsunami between 09:30 and 10:00. The earthquake was also reported in historical Japanese documents ranging from 8 and 10 o’clock in local time.

中文翻译：

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根据北美西海岸的潮汐记录估算1854年安塞-东海海啸的起源时间。

我们根据在北美西海岸三个潮汐测量站（阿斯托里亚，旧金山和圣地亚哥）记录的海啸波形，估算了1854年安塞—东海海啸的起源时间。海啸信号在旧金山和圣地亚哥的记录中很明显，到达时间是1854年12月23日格林威治标准时间（GMT）下午0-1时，而阿斯托里亚海啸信号则是模棱两可的，到达时间不可能是由波形确定。基于非线性色散波理论的仿真波形，假设12月23日格林尼治标准时间0的起源时间早于观测。在旧金山和圣地亚哥记录的观测波形与模拟波形之间的互相关函数表明它们之间的时间间隔约为30分钟。根据这些结果，我们得出的结论是，1854年安塞—东海海啸的起源时间大约是格林尼治标准时间凌晨00:30或12月23日当地时间09:46。我们的结果与驻扎在下田湾的一艘俄罗斯护卫舰的报道大致吻合，地震发生的时间为09:00至09:45，海啸发生于09:30至10:00。日本历史上当地时间8点至10点的文件也报道了地震。