地震震级—频度G-R关系的偏离度

假设震级—频度分布服从对应于G-R式母体分布污染的情况,文中引进震级分布偏离度(ζ)来描述实际资料分布与G-R式的偏离程度。在G-R式分布参数稳健估计的基础上给出了偏离度的计算方法。华北地区1980—1993年取资料时间窗长1年,滑动步长1个月的ζ值计算结果表明,6级左右强地震前的半年至一年半左右ζ值明显为相对稳定的低值,震后呈高值变化。它可能反映了强震孕育发生过程中地震活动强度分形结构的变化,存在一个有序态(确定性)和无序态(浑沌)转化的自组织性质。ζ值可在地震预报中作为一个分析判定指标。

DEVIATION BETWEEN MAGNITUDE-FREQUENCY STATISTICS AND G-R RELATIONSHIP

Assumed that the magnitude-frequacy distribution should obey the G-R formula but a noise pollution, the authors introduced the deviation to describe statistical deviation of the G-R formula, an estimation method for working out the deviation has been given. The value for northern China from 1980 to 1993 (the time window for selecting data is one year and the slip step is one month) indicates clearly that maintains in a stable low value relatively before strong earthquakes with Ms = 6. and the low value continues for about half a year to one year. After a strong event, value becomes higher with a small rise and fall. This feature may represent the existence of a self-organized property, which changes between an ordered state ( deterministic) and a disordered state ( chaos) in the seismogeny and seismicity process. And this alteration between deterministic and choas state occurs with the change of magnitude distribution fractal demention. Finally, the authors found that c can be regarded as an index for prediction of strong earthquakes.