| Disasters have characteristics of human nature, because of earthquake disasters is difficult to predict, the number of deaths is in the first of all kinds of natural disasters, and the economic loss is immeasurable. Fen nutrient-laden basin is one of the main earthquake activity in the seismic tectonic zone of north China. The historical earthquake activity is strong and have large population density. The research on the rules in time and space of earthquake disaster have profound meaning, to some extent, it can reduce the extent of the damage.This paper selected Fen wei basin as study area, analyzed the space and time laws of historical earthquakes in this area. According this aera present "S" shape, like echelon distribution and its earthquake energy has zoning characteristics, this paper divided the Fen wei basin into three earthquake zone, as the North, the Middle, the South zone. Based on the analysis of time and space symmetry of Seismogenic time and epicenter in different earthquake zone since 1900, the paper made the trend judgment from time and space. Then it did the preliminary discussion to Fen wei basin and related factor (sunspot activity cycle, the phases of the moon, the earth’s rotation rate parameter). The main conclusions in this paper were as follows:(l)The Ms≥6.0 earthquakes presented rhythmic of active and quiet period since A.D.. The epicenter completed four swing upward migration, showing obvious migration patterns in west and east, north and south. Thus judging the next earthquake was located in the south of 40°N and east of 114° E. The Ms≥6.0 earthquakes occurred near the syzygy in Fen wei basin, and it had highest frequency in new moon.(2)The time window Period of next Ms≥5.1 earthquake is 2015,2016 in the all region, the epicenter location is 40.2°N,114°E. The time window Period of next Ms≥4.3 earthquake is 2016,2021, the epicenter location is in the west of 114°E, north of 40°N. The time window Period of next Ms≥4.5 earthquake is 2015,2023 in the middle, the epicenter location is in north of 37.45°E and west of 112.4°E. The time window Period of next Ms≥4.4 earthquake is 2036,2041 in the south, the epicenter location is in north of 34.3°N and west of 109.4°E.(3) Statisticing earthquake years and sunspot activity in Fen wei basin from 1900, it found that the falling period has higher seismogenic frequency in all region, seeing from the sunspots rising and declining period, while the rising period has higher seismogenic frequency in the north. From the perspective of extremum years, the Minimum years has higher seismogenic frequency in the south, on the contrary, the maximum years in the north and middle district. From the aspects of the single and double cycle of sunspots, the earthquake frequency in declining period of double cycle is highest, followed by the rising period of single and double period. The earthquake frequency in Single cycle of extremum years is higher than the double cycle, and the valley years in single cycle is highest. The extremum years in double cycle is higher in the north, while single cycle in middle and south.(4) Studying the relation between Phases of the moon and earthquakes in different zones, it is concluded that the probability of the earthquake near syzygy is the middle> the south> the north. Intuitivly, the relationship between earthquake and phases of the moon is not very clear and have strong randomness in Fen wei basin since 1900.(5) Studying the relation between the earth’s rotation and earthquakes. It found that the earthquake probability in reduction period is greater than acceleration period. The frequency is equal between the reduction period and the acceleration period in all region; The frequency of acceleration period is less than the deceleration period in the north and middle; while bigger in the south. Namely, the earthquake probability of acceleration period is bigger in the north and middle, while deceleration period in the south.(6) The time of earthquake is almost the same and has synchronization seismic activity between western Ordos block and Fen wei basin. The Seismgenic time of Fen wei basin is around 1-3a to western Ordos massif. The earthquake in Fen wei basin occurred before in western Ordos massif when western Ordos massif during calm, On the contrary, the earthquake in Fen wei basin occurred after western Ordos massif during active period. To some extent, it instructions that the seismic activity has mutual influence and interaction between western Ordos block and Fen wei basin.The study in this paper riches disaster trend research, increases disaster verification case and provides important basis for disaster prevention and mitigation. |
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