An application of Bayesian (ABIC) smoothing methods to estimating space and time variations in the magnitude distributions of earthquakes
✍ Scribed by Masajiro Imoto
- Publisher
- Springer Japan
- Year
- 1991
- Tongue
- English
- Weight
- 940 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0020-3157
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✦ Synopsis
On the basis of Akaike's Bayesian information criterion (ABIC), a new method of estimating temporal and spacial variations in the magnitudefrequency relation (b value) is developed. The space-time volume studied is divided into a number of segments having equal volume, for which b values are estimated. The smoothness of the estimated b value is guaranteed by the introduction of a prior distribution. The parameters of the prior distribution are chosen in such a way as to minimize the ABIC. This method is employed to study the temporal and spatial variations of b values for microearthquake activity in the Kanto, Tokai and Tottori areas, where seven earthquakes having magnitudes of M6.0 and larger have recently taken place. States of temporal variations of b values are classified into three groups; increase, decrease and nochange. The space-time volume of decrease accounts for approximately 10% of the total volume. For a period before the occurrence of earthquakes, the decrease appears more frequently than might be expected. It is concluded that the decrease in the b value is a promising candidate to act as a precursory phenomena.