Abstract:

Recently, Chinese Geographic Name Database was published, based on which the author has located as many as 5825 coalmines. “Replayed” by natural order, it has been found that 48.7% of coalmine disasters did not occur randomly, but tended to occur continuously within certain scopes, presenting cluster feature, some accompanied with earthquakes (with magnitude>3), in which all the disaster types are involved. In further research, with micro earthquakes introduced, quite a few coalmine disasters are found to be accompanied with micro earthquakes, in which earthquakes tended to occur earlier than coalmine disasters. Of all the causative factors, stress disturbance is the only one that can cause all kinds of disasters at one time. The earthquakes accompanied with disasters may be the vital geophysical evidence of the tectonic stress fluctuation around mining area(causing coalmine disasters). This paper made a quantitative research, by which the ratio of disasters involved in cluster series and the number of earthquakes accompanied with disasters are achieved. For example, under threshold of 100 miles, of all the 7368 disasters, at least 38.5% are involved in cluster series, in which 372 disasters are accompanied with earthquakes. Of all the cluster series, the proportion of the durations sorted by descending order is 2 days, 1 day, 3 days, 4 days, …, 11 days. Potentially, the duration of cluster series reflects the duration of stress disturbance. The majority of the durations are composed of short ones, such as 1 and 2 days, which correspond well earthquakes (with magnitude<5) and are speculated to be more likely related to local stress disturbance. While the minority long durations correspond well with fatal earthquakes, which are speculated to be related to regional stress disturbance. In addition, all the cluster series under every threshold have been picked out successfully and a full open access is provided. As to the mechanism, the author makes the most common speculations on a given geological model, in which five affecting cases are analyzed. The phenomena remain unknown to human, which, to earthquake research and coalmine disaster prevention, widely scientific significance is suggested.

Key words: cluster, earthquake, coal mine disaster, stress disturbance