Relationship between the lunar tidal force and earthquakes in Taiwan

• Main Authors: Ya-Chi Weng, 翁雅琦
• Other Authors: Ruey-Juin Rau
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/85237104424081570120

碩士 === 國立成功大學 === 地球科學系專班 === 97 === In this paper we use earthquake data in Taiwan from Central Weather Bureau for the period of 1991-2008. We calculate the distance from the moon to the earth and the solid tidal force by using the software, Multiyear Interactive Computer Almanac (MICA). From the phase of earth tide we discuss the relationship between the lunar tidal forces and the earthquake occurrence time. Besides, we analyze the correlation between the lunar tidal force and larger earthquakes (Ms≧7.0) using the earthquake data in 20th century. Our results indicate that: (1) In Taiwan, the correlation between earthquake occurrence and the phase of half-day tide is not so clear, and the correlation between earthquake occurrence and the phase of half-month tide is influenced by the Chi-Chi earthquake. (2)According to the data from 1991 to 2008, earthquakes occurred at the advantage azimuth range are closely related to the mainshock and aftershocks of Chi-Chi earthquake. If ignoring the influences of the mainshock and aftershocks of Chi-Chi earthquake, the relationship between the lunar tidal forces and the earthquake occurrence time is not clear. (3) According to an analysis of 24 earthquakes with magnitudes larger than 7.0 from 1900 to 1999 year, 54.17％ of earthquakes occur at the increasing of half-month tidal force, other 45.83％ of earthquakes occur at the decreasing of half-month tidal force. And in the period of increasing half-month tidal force, 81.82％ occur at the phase of half-month tidal force at the peak or foot of the phase of tidal force. This indicates that when the tidal force near the extreme value, earthquakes may occur easier.