[分享]震级分类(The Classification of Earthquake Magnitude)

震级分类(The Classification of Earthquake Magnitude)

目前世界上记录到的震级最大的地震是哪次？为什么有人说是2011年日本大地震，有人说是1960年智利大地震，还有人说是2004年印度洋大地 震？即便是同一次地震，比如2004年印度洋大地震，有人说是8.6级，有人说是8.9级，还有人说是9.0级？要解答这些问题，我们首先要明白震级的划分方法。Lkv七二检测-检测人身边的百科全书

目前，最基本震级标度有4种，里氏震级ML，体波震级MB，面波震级Ms，以及矩震级Mw。其中里氏震级，体波震级和面波震级均为波震级。Lkv七二检测-检测人身边的百科全书

Lkv七二检测-检测人身边的百科全书

世界上比较通用的是里氏震级(The Richter magnitude)，其最初定义为里克特（Richter）于1935年提出的，里氏震级大小是指用标准地震仪在距震中(Epifocus)100公里处记录的以微米为单位的最大水平地面位移A的常用对数：ML=log（A）。由于里氏震级要用到距震中100公里处的地面位移，由于我们不知道哪天会发生地震，因此也不可能地震发生时恰巧把地震仪放置在距震中100公里处。因此我们分别针对近震(Local Earthquake)和远震(Distant Earthquake)引入了体波震级和面波震级。矩震级是由加州理工学院的金森博雄（Hiroo Kanamori）教授于1977年提出的，该标度能更好的描述地震的物理特性，如地层错动的大小和地震的能量等。Lkv七二检测-检测人身边的百科全书

不论采用什么震级，由于地震波传播介质的差异，同一次地震在不同地点确定的震级常常不同，差别常达0.3~0.5，有时甚至超过1.0。Lkv七二检测-检测人身边的百科全书

Lkv七二检测-检测人身边的百科全书

至于世界上记录到的震级哪次最大，这要从波震级和矩震级两个角度来考虑，从波震级角度考虑，日本2011年大地震里氏9.0级（日本气象厅给出的数据）居首位，与2004年12月26日印尼苏门答腊岛北部以西近海9.0级特大地震并列第一。从矩震级角度来考虑，1960年智利大地震应该排在第一（矩震级9.5），排在第二的是2004年12月26日印度洋大地震（矩震级9.3），第三位是日本2011年大地震（矩震级9.0）。Lkv七二检测-检测人身边的百科全书

Lkv七二检测-检测人身边的百科全书

Which one is the largest Earthquake in Magnitude reordered up to now? Some people said it should be Japan Earthquake in 2011. Some people think that it should be Chile Earthquake in 1964. And others said it should be Indian Ocean earthquake in 2004. Even for the same earthquake, for example, the Indian ocean earthquake in 2004, its magnitude has different versions, reported as 8.6, 8.9 and 9.0. To answer these questions, we must first understand the classification method of magnitudes.Lkv七二检测-检测人身边的百科全书

At present, there are 4 kinds of magnitudes scales, including the Richter magnitude ML, the body wave magnitude MB, the surface wave magnitude Ms, and the moment magnitude Mw. The Richter magnitude, the body wave magnitude and the surface wave magnitude are all wave magnitudes.Lkv七二检测-检测人身边的百科全书

The Richter magnitude (ML), which was originally proposed by Richter in 1935, is defined as the logarithmic of the maximum horizontal displacement with micron recorded by a standard seismograph on somewhere with the epicenter distance of 100km, ML=log(A). We don’t know when and where an earthquake will happen, so it is impossible that a seismic instrument is happened to be installed at a location with the distance of 100 kilometers to the epifocus when a earthquake occurs. So,the MB and MS are introduced to respectively responsible for the local Earthquake and Distance Earthquake. The moment magnitude Mw was introduced by professor Hirookanamori from California Institute of Technique Caltech in 1977,which can perfectly describe the physical characteristics of an earthquake, such as the fault deformation and the released energy.Lkv七二检测-检测人身边的百科全书

Regardless that what kinds of magnitudes areselected, due to the differences in the medium of seismic wave propagation, the same earthquake may be determined as different magnitudes at different locations, in which the difference is often 0.3~0.5, sometimes even more than 1.Lkv七二检测-检测人身边的百科全书

Concerning the world's largest magnitude amongthe recorded earthquakes, it should be considered from two views, wave magnitudeand moment magnitude. From the view of MW, Japan earthquake of 9.0 on the richer scale in 2011(the datum from Japan meteorogical agency) is the largest. And the great earthquake of west offshore in northern Sumatra Indonesia on December26, 2004 is the second largest one with the magnitude of 9.0. From the perspective of moment magnitude, the earthquake in Chile in 1960 should be rank first (moment magnitude 9.5); the second one is Indian Ocean earthquake (momentmagnitude 9.3) on December 26, 2004 , and the third one is the Japanese earthquake (moment magnitude 9.0) in 2011.Lkv七二检测-检测人身边的百科全书

Lkv七二检测-检测人身边的百科全书