Nicola Scafetta has co-authored a paper with Adriano Mazzarella on the correlation of the spectral frequencies of M7 and greater earthquakes and oceanic oscillations and length of day (LOD). He ascribes those oscillations and the LOD variation to the astronomical forcings identified in earlier papers which have similar spectral frequency peaks.
We compare the NOAA Significant Earthquake Historical database versus typical climatic indices and the length of the day (LOD). The Pacific Decadal Oscillation (PDO) record is mainly adopted because most of the analyzed earthquakes occurred at the land boundaries of the Pacific Plate. The NOAA catalog contains information on destructive earthquakes. Using advanced spectral and magnitude squared coherence methodologies, we found that the magnitudeM≥7earthquake annual frequency and the PDO record share common frequencies at about 9-, 20-, and 50- to 60-year periods, which are typically found in climate records and among the solar and lunar harmonics.