今天是唐山大地震的纪念日。
Today is the anniversary of the Tangshan earthquake.
唐山大地震是1976年7月28日凌晨3：42分发生在中国河北省唐山市的7.8级地震。
Tangshan earthquake was a natural disaster resulting from a magnitude 7.8 earthquake that hit the region around Tangshan, Hebei, People's Republic of China on July 28, 1976, at 3:42 in the morning.
地震一共造成242,769人死亡，164,851人重伤，唐山市夷为平地。
In minutes the city of Tangshan, an industrial city with approximately one million inhabitants, ceased to exist. Eighty-five percent of the buildings in the city collapsed or were unusable, all services failed, and most bridges collapsed or were seriously damaged. At least 242,769 people died.
我的专家老师告诉我，唐山地震伤亡如此巨大的原因是因为唐山市的建筑设计时都没有考虑地震的情况，唐山的主要建筑都是没有抗震设施的砖结构建筑。
All buildings and structures of Tangshan were designed and built without seismic considerations. As a result, Tangshan was "mainly a city of unreinforced brick buildings”,sitting on top of a major earthquake.
我的专家老师还告诉我，华北地区历史上地震就很多，间隔大约是300年左右。
My teacher also told me that there have been many earthquakes in the history of north China, with an interval of about 300 years.
我不太相信这种观点，所以查了历史资料，汇总情况如下。
I don't really believe this, so I checked the historical data and summarized them as follows.
1、华北地区的范围
The scope of north China
2、华北地区历史上的地震
Historical earthquakes in north China
从1480年至今，震级在6~6.9级之间的地震有98次，震级在7~7.9级之间的地震有30次，震级在8级以上的地震有6次。
From 1480 to the present, There were 98 earthquakes with magnitudes between 6 and 6.9, There were 30 earthquakes with magnitudes between 7 and 7.9, There have been six quakes of magnitude 8 or greater.
8级以上地震包括１556年陕西华县８.25级地震、1668年山东郯城８.50级地震，以及1679年三河~平谷8级地震。
Earthquakes of magnitude 8 and above include magnitude 8.25 in Huaxian, Shanxi province in 1556, magnitude 8.50 in Tancheng, Shandong province in 1668, and magnitude 8 in Sanhe-Pinggu, Hebei province in 1679.
3、地震规律研究
Study of seismic law
按照很多专家的观点，华北地区的地震活动具有300年左右的活动周期，未来百年处在第三活动期的后期。
According to many experts, seismic activity in north China has a period of about 300 years,
and the next hundred years are in the latter part of the third active period.
