Optical clocks improved the accuracy of state-of-the-art cesium clocks by more than two orders of magnitude and enabled frequency comparison with a fractional uncertainty of one part in 10¹⁸. Gravitational redshift of two such clocks allows determining their height difference with an uncertainty of 1 cm. In Europe, chronometric leveling has been extensively conducted for unifying the height reference systems. Temporal response of the leveling, which affords monitoring a cm height variation within hours of averaging time, may offer new opportunities to explore seismology and volcanology. Superb stability of optical lattice clocks will be best used for such applications. This article outlines the prospects of chronometric leveling in Japan. Combining optical lattice clocks with an existing observation network of GNSS, crustal deformations may be monitored with unprecedented accuracy in the future.

光学时钟将最先进的铯钟的精度提高了两个数量级以上，并使频率比较具有 10 分之一的不确定性¹⁸. 两个这样的时钟的引力红移允许以 1 厘米的不确定性确定它们的高度差。在欧洲，为了统一高度参考系统，已经广泛进行了计时水平测量。平整度的时间响应可以在平均时间的数小时内监测厘米的高度变化，这可能为探索地震学和火山学提供新的机会。光学晶格时钟的卓越稳定性将最适合此类应用。本文概述了日本计时调平的前景。将光学晶格钟与现有的 GNSS 观测网络相结合，未来可以以前所未有的精度监测地壳变形。