地震引发的海啸登陆之前,会有一些非常明显的宏观前兆现象,在海边生活、工作、旅游的人们只要稍加注意,就可以发现.常见的海啸登陆宏观前兆现象大致有四种：一是海水异长的暴退或暴涨；二是离海岸不远的浅海区,海面突然变成白色,其前方出现一道长长的明亮的水墙；三是位于浅海区的船只突然剧烈地上下颠簸；四是突然从海上传来异常的巨大响声,在夜间尤为令人警觉.
这四种宏观前兆现象是由海啸发生和传播的机制造成的.海底发生地震,如果造成海底地壳大范围大幅度沉降,就会引起大范围海水大幅度下沉,距离震中较近的沿海就会看到海水异常的暴退现象；如果地震造成海底地壳大范围大幅度隆起,就会引起大范围海水大量聚集,距离震中较近的沿海就会看到海水异常暴涨现象.
海水异常的暴退或暴涨,有几个异常的特征：海水退、涨的时间与平常的退潮、涨潮时间不一致；海水退、涨速度比平常的速度快得多；海水退、涨的幅度大,常能退到最低潮线以下,或涨到最高潮线以上.
海水异常的暴退或暴涨现象,距离震中数百公里以内的沿海都能看到,远离震中数公里的沿海,则不易看到.海水暴退或暴涨现象在震后出现的时间,因各地距震中的远近不同而有所差异,有的紧随主震之后,有的主震后10－20分钟.从海水暴退或暴涨现象出现到海啸登陆,间隔的时间也有长有短,短的仅有几分钟,长的可达到几十分钟.
海啸波是重力长波,波长可达100公里以上；它的传播速度等于重力加速度（9．8米／秒）与海水深度乘积的平方根,所以,海水越深,海啸波速度越快,海水越浅,海啸波速度越慢.当海啸波由远离海岸的深海区,进入海岸附近的浅海区后,波速便急剧降下来,后面的波速依然很快,后波就追上了前波,前后波相叠加,便使波浪的高度倍增,形成几米、甚至几十米高的巨浪.因此,在离海岸不远的浅海区深蓝色海面就会突然变成白色,并在其前方出现一道长长的明亮的水墙；位于浅海区的船只就会突然剧烈地上下颠簸起来；海面上也会响起巨大的、惊人的、可怕的咆哮声.四种前兆现象,是海啸临近的标志,是灾难预警信号,它警示人们：海啸即将登陆,要生存,赶快向高处逃跑,否则,长则十几分钟,短则几分钟,甚至只有几十秒,就会被巨浪吞没.
译文---------
Tsunami earthquake before the landing, there will be some very obvious precursor of macro-phenomena, at the seaside to live, work, travel a little attention as long as people can be found. Common precursor macro-tsunami landing Generally, there are four: First, different length of the sea or soaring; Second, from the shallow water areas near the coast, the sea suddenly turned into white, which appears in front of a long bright water wall; three areas are located in shallow water vessel suddenly bumps up and down violently; Fourth abnormal suddenly came from the sea the great sound, is particularly alert at night.
The four macro-precursory phenomena and dissemination by the tsunami caused by the mechanism. Undersea earthquake, if the seabed caused by a substantial large-scale settlement of the earth's crust, sea water will cause a substantial large-scale subsidence from the epicenter along the coast close to the sea you will see the phenomenon of abnormal; Harbor if the earthquake caused large-scale crustal large rate of uplift, the water will cause a large number of large-scale gathering, from the epicenter along the coast close to the abnormal rise of sea water will see the phenomenon.
Abnormalwater or soaring, there are several unusual features: the sea retreated, up time and the normal low tide, high tide time differences between; sea retreated, speed up the pace much faster than usual; the water retreated, the extent up can often be back below the lowest, or rise above the high point.
Sea water or soaringabnormal phenomenon, hundreds of kilometers from the epicenter of the coastal can see a few kilometers away from the epicenter along the coast, it is not easy to see.or surge of sea water after the earthquake phenomena occur in time, due to the distance from the epicenter around vary, and some immediately after the main shock, some 10-20 minutes after the main shock.or rise from the sea to the tsunami phenomenon landing, the time interval with a long short, short period of only a few minutes longer to reach tens of minutes.
Tsunami waves are long waves of gravity, the wavelength of up to 100 kilometers above; its velocity equal to the acceleration due to gravity (9.8 m / s) and the product of the square root of water depth, so the deeper the water, the faster the tsunami wave, the more shallow water , the slower the speed of tsunami waves. When the tsunami waves from deep-sea areas far away from the coast into the shallow water areas near the coast, the wave velocity will be down sharply, after the velocity is still very fast to catch up after the first wave on wave after wave of superposition as a result, the wave high multiplier, the formation of a few meters or even tens of meters high waves. Therefore, from the coast in shallow water areas near the sea of dark blue will suddenly become white, and appear in its front a long wall of the bright water; the vessel is located in shallow water areas will be a sudden sharp bumps up and down together; sea will also sounded great, amazing, terrible roaring sound. Four precursor is a sign of approaching tsunami is a disaster early-warning signal, it warns people: The tsunami is about to visit, it is necessary to survive, to escape upward as soon as possible, otherwise, is ten minutes long and short is a few minutes, or even only a few dozen seconds, will be huge waves swallowed.