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■青海玉樹地震(圖)導致過千人死亡。有人認為，近半年接連發生強烈地震，可能顯示地球已經進入地震活躍期。 資料圖片
進入2010年後，整個地球可謂小震不斷，大震常有。海地、智利、台灣高雄、土耳其、墨西哥、印尼、青海等地先後發生強震。今年以來累計數十次大小地震，讓很多人不禁產生這樣的疑問：地球是否進入新一輪地震活躍期？
關於地球是否進入地震活躍期的問題，國家地震局中國地震台網中心首席預報員孫士鋐表示，地震活動的頻率高低具有一定的周期性規律，綜合百年來各階段的數據，無論從地震頻率或地震強度上看，都可說現在全球進入地震多發期。1900年至1964年期間，全球共發生8.5級以上地震7次；1964年美國阿拉斯加大地震後到2004年間，全球沒有發生8.5級以上強震。而2004年至今，短短6年內發生印尼兩次震級分別為8.7級和8.5級的地震，今年智利發生8.8級地震，共3次屬8.5級以上強震。
國家地震局局長陳建民則認為，今年1月以來，全球發生多次地震，大都集中發生在人口密集的地方，給人們造成地震頻發的印象，並認為全球進入地震活躍期，這是缺乏依據的。他認為，需要進一步觀察，不能輕易下結論。
中國地震台網中心預報部主任劉傑亦表示，全球是否進入地震活躍期，今年前幾個月尚難定論，需要更長時間來觀察。
Has the Earth Entered a Period of Frequent Earthquake Occurrences?
Since the start of 2010, there have been numerous minor and quite some major earthquakes around the world. Places like Haiti, Chile, Kaohsiung in Taiwan, Turkey, Mexico, Indonesia and Qinghai have been hit by large quakes successively. So far, dozens of earthquakes of varying magnitudes have been registered in aggregate this year. People therefore start to wonder whether the Earth has entered a new phase of frequent earthquakes.
Regarding whether the Earth has entered a period of high seismic activity, Sun Shihong, chief forecaster of the China Earthquake Networks Centre which is under the China Earthquake Administration, said that the frequency of seismic activity displays certain periodic patterns. He believed that we have now entered a period of frequent earthquake occurrences, in terms of both frequency and magnitude, based on the data collected in various stages over the last hundred years. From 1900 to 1964, only 7 earthquakes of magnitude 8.5 or above had been registered worldwide. Then, from the year 1964 when a large earthquake hit Alaska, to the year 2004, there was not a single occurrence of an earthquake of magnitude 8.5 or above. However, in just 6 years' time from 2004 to this date, there were already two earthquakes with a magnitude of 8.7 and 8.5 respectively in Indonesia. Together with the one in Chile, which had a magnitude of 8.8, so far this year, there have been in total 3 occurrences of strong earthquakes with magnitude 8.5 or above.
However, Chen Jianmin, Director General of China Earthquake Administration, said that as quite a number of earthquakes had been registered since January this year and most of them happened in densely populated areas, people might come up with the impression that there has been a high frequency of earthquake occurrences and that the Earth has entered a period of high seismic activity. He believed that this claim lacks grounds, and further observation is needed before a conclusion can be drawn.
Liu Jie, Director of the Forecast Division of the China Earthquake Networks Centre, expressed a similar view. On whether the Earth has entered a period of high seismic activity, he said that it is difficult to reach a conclusion in the first few months of the year. He thought that a longer period of observation is necessary. ■Translation by開明
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