A possible link between Earth tides and earthquakes

• Main Authors: Kansowa, Tarek (Author), Tatnall, A.R.L (Author)
• Format: Article
• Language: English
• Published: 2010.
• Subjects: Article
• Online Access: Get fulltext

 The ability of Earth tides to trigger earthquakes has been investigated statistically. Earthquakes occurring in the South of California and the Parkfield area with magnitude Mw ? 4.5 during the period 1973 to 2007 have been used. The earth tides vertical displacement has been calculated at the location and time of each earthquake. The relation between Earth tides and earthquake occurrences is measured statistically by applying Schuster's test. Each earthquake is assigned a phase angle between -180 and 180 degrees based on its occurrence time with respect to the local Earth tides. The value of p is used to determine the null hypothesis that earthquakes occur randomly with respect to the phase angle of the tidal variation. No significant correlation is observed between earthquake occurrence and Earth tides for the data set including all earthquakes. By classifying the data set according to the earthquake depth, a significant correlation has been found for shallower earthquakes (depth ? 6 km). A further analysis has explored the relationship between the earthquake occurrence and the Moon phase. The same data set has been used and Schuster's test indicates that there is a high relation between earthquake occurrence at shallow depths (depth ? 12 km) and the full Moon. The presence of aftershocks, however, does require a more detailed analysis to establish the true significance of this result as aftershocks can lead to clustering of earthquakes that could bias the results.