Earthquakes in China

Introduction

China is located in one of the most active seismic regions of the world and has been plagued by numerous destructive earthquakes during its long history. The most significant of these earthquakes, in terms of lives lost, was that which occurred in 1556. In the last twenty years China has experienced the second most destructive earthquake in its history. The following is a brief account of the 1556 and the recent 1975 and 1976 earthquakes.

The Great China Earthquake of 1556

The worse natural disaster in recorded history, at least in terms of lives lost, was caused by an earthquake in Hausien in the Shensi Province of China in 1556. The earthquake devastated 98 counties and eight provinces of Central China. The destruction spanned an area of 500 miles, and in some counties the average death toll was 60 percent of the population. A total of 830,000 people lost their lives, most of them from the collapse of poorly constructed houses. The magnitude of this earthquake has been estimated to be from 8.0 to 8.3 on the Richter scale.

The Haicheng Earthquake of February 4, 1975

On February 4, 1975, Haicheng, a town with about 100,000 inhabitants in the Liaoning Province of northeast China, was struck by a 7.3 magnitude earthquake. As early as 1970, the State Seismological Bureau, had identified the Liaoning Province as an area of high earthquake risk. Based on studies of precursor events and unusual animal behavior, a warning was issued by local authorities. Thus, when the earthquake struck on February 4, there were few lives lost as most inhabitants had evacuated to safer places. However property damage was high.

The China Earthquake of July 28, 1976 (The Tangshan Earthquake)

No other earthquake in this century has been as catastrophic or has claimed as many lives as the great earthquake that struck the city of Tangshan, in Northern China, on July 28, 1976. Tangshan, a thriving industrial city with one million inhabitants, is located only about 95 miles east, and slightly south, of Beijing. Although the region had experienced moderate seismic activity in the past, the city of Tangshan has been built on unstable, alluvial soil. To make matters worse, The city is located in the center of an area with major crustal faults on four sides. Furthermore, a 25-mile long fault passes through Tangshan, where only few of its structures are earthquake-resistant.

In the early morning hours of July 28, while the city was asleep, the magnitude 8.0 earthquake with its epicenter right on the city broke a five-mile section of the fault. Along the west side of the fault the land moved five feet northward in relation to the land on the east side. The east block tipped downward at the northern end of the break, and upward toward the south end. Over a four-by-five mile area the devastation of the city was nearly total. The force of the quake motions were so strong that people reported being thrown in the air. Within seconds, thousands died. Property destruction was unbelievable. Bridges, railroads, homes, factories were completely leveled. In the harbor city of Tientsin, 60 miles to the southwest, and in Beijing to the west, the quake jolts forced thousands of frightened people into the streets seeking refuge from aftershocks.

导言

中国是世界上地震最活跃的地区之一，在其悠久的历史中，曾遭受了许多破坏性的大地震。就人员伤亡而言，1556年发生的大地震损失最为惨重。在过去的二十年里，中国还经历了另一个最破坏性的大地震。以下是简1556以及最近的1975年和1976年的特大地震的简单介绍。

1556年特大地震

就伤亡人数来说，有记载最严重的自然灾害，是1556年发生在陕西华县的超强地震，那次地震共摧毁了中国中部地区的8个省和98个县。破坏范围面积达500英里，因为房屋简陋，83万人失去了生命。在一些受灾县，平均死亡人数为60 %。据估计，这次地震为里氏8.0到8.3级。

1975年2月4日海城地震

1975年2月4日，在中国东北辽宁省的海城，一个约有十万居民的镇，发生了7.3级的特大地震。早在1970年，国家地震局就把辽宁省确定为地震高风险地区。当地政府根据震前先兆与动物的反常行为，发出了地震预警。当二月四日爆发大地震时，因为大部分的居民已疏散到安全的地带，生命损失很少。不过财产损坏很大。

1976年7月28日特大地震(唐山大地震)

在本世纪，没有任何其他大地震能与发生在1976年7月28日中国北方的唐山市所造成的巨大灾难或死亡人数相比的特大地震。唐山位于北京东部偏南95英里(原文如此，译者注)，人口一百万，是一个繁荣的工业城市。过去该地区曾经历过中度地震活动，唐山市的地基不稳定，土壤为冲积土质。更为糟糕的是，唐山正好处于四周为主要的地壳断层的区域中心。此外， 25英里长的断层带正好通过唐山，唐山的建筑物结构很少具有抗震性。

7月28日清晨，整个城市还在睡梦中，突然爆发了8.0级特大地震，震中在断层的5英里处，正好是唐山市的中心位置。与东侧相对而言，沿着断层的西侧整个土地向北移动了5英尺。在裂缝处北端东部，地块北向下倾斜，南边翘起。整个唐山几乎全部夷为平地。有报道说，地震的威力之强大把人都抛到了空中。顷刻间，数千人丧失了生命。财产的损失更是难以置信。桥梁、铁路、房屋、工厂完全夷为平地。在西南60英里以外的港口城市天津，及西面的北京，大地震动迫使数以千计受到惊吓的老百姓在后来的多次余震中露宿街头寻求安全。