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| The solar and lunar effect of earthquake duration and distribution |
| Zhenxia Zhang, Shugui Wu, Jianyong Li |
| National Earthquake Infrastructure Service, China Earthquake Administration, Beijing 100036, China |
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Abstract Phase folding algorithms are conventionally used in periodicity analyses using X-ray astronomy pulsar. These allow for accurate identification of the cycle and phase characteristics of the physical parameters of the periodic variation. Although periodic variations in earthquake activity have long been studied, this paper is the first to apply the phase folding algorithm to the analysis of shallow (<70 km) seismic data for the period 1973–2010. The goal is to study the phase distribution characteristics of earthquake frequencies and we see a connection between earthquake occurrence and solar and lunar cycles. First, the rotation of the Sun may play a significant role in impacting on the occurrence time of earthquakes with magnitudes of less than 6.0. This may be especially pertinent for earthquakes with magnitudes between 5.0 and 6.0, when the modulation ratio reaches 12 %. The Moon’s gravity, which is generally thought to have the greatest influence on the global environment, may actually play less of a role on earthquake timing than the rotation of the Sun. Second, when we consider the world to be divided into 72 local regions based on latitude and longitude, we can see that there are more than a dozen regions with significant nonuniform distributions of earthquake occurrence time. In these regions, the ratio of χ2 to the number of degrees of freedom far exceeds five. As a result, we posit that some factors associated with the Sun–Earth–Moon relationship may trigger earthquake activity under certain temporal and spatial conditions.
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Received: 28 April 2013
Published: 29 November 2013
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| Fund:special funds from the Welfare industry (201108004) and the Seismic Science and Technology Spark Plan of the China Earthquake Administration (XH12066) |
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Corresponding Authors:
Zhenxia Zhang
E-mail: zxzhang@neis.gov.c
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