2025 Volume 81 Issue 13 Article ID: 24-13509
We analyzed the strong ground motions during the Noto Peninsula earthquake using duration spectra representing three essential factors of amplitude, period and duration. Using horizontal two components of accelerograms recorded in Noto area, we evaluated the spectra representing the uniform duration of velocity response envelope exceeding various levels of threshold. Comparing them with JR Takatori station during the 1995 Hyogo-ken Nanbu earthquake, we found that durations in the period range of 1-3 s at JMA Fugeshi and other stations exceed those at JR Takatori. Next, we discussed the ratios of energy spectra to velocity response spectra as the effect of long duration based on the random vibration theory. We also evaluated the directionality of energy spectra that account for concentration of energy input along the predominant direction.
