[分享]地震工程术语(TerminologiesofEarthquakeEngineering)
地震工程术语(Terminologies of Earthquake Engineering)
I will introduce some Terminologies in Earthquake Engineering today.
Focus,Center or Hypocenter: Earthquake is a disturbance in a form of energy comes from displacement of a fault after having accumulated. The point where the slip begins/the fault ruptures is the focus of an earthquake, we call it hypocenter, focus or center.
Epifocus or Epicenter: The projection of focus on the surface of the earth is epicentre. It is simply a point on a map where the earthquake locates.
Epicenter Distance: The distance from the epicenter to the point of the observed ground motion.
Focal Depth: The depth of hypocenter below the epicenter.
According to the focal depth, the earthquakes can be classified as shallow focus earthquake, Intermediate focus earthquake and deep focus earthquak.
Shallow-focus earthquakes occur at depths less than 70 km. SHALLOW FOCUS earthquakes are commonly occurring “crustal” earthquakes, caused by faults and movements of the continental plates. These are earthquakes with their focus nearer the surface of the earth. Shallow focus earthquakes are usually of large spread, causing greater damage at the surface or the earth’s crust. These occur quite frequently and at random. However, being of smaller magnitudes and at lesser depths, very often they are not even felt. Nevertheless, about 75 % of the world’s energy released from earthquakes is from shallow-focus ones.
Deep-focus earthquakes occur at greater focal depths of 300 – 700 km. DEEP FOCUS earthquakes or “intra plate” earthquakes, occur within the sub-ducting oceanic plates as they move beneath the continental plates. Appearing along fault lines, these are earthquakes with focus much deeper within the earth. A deep focus earthquake occurs when two tectonic plates slide towards one another followed by subduction, or when the mineral olivine is in a transitional phase.These are typical of the subduction zone of the earth which are seismically active zones, often existing in patterns as in Wadati-Benioff zones. They happen as huge quakes with larger magnitudes, as a great deal of energy is released with the forceful collision of the plates.
今天介绍几个跟土木工程相关的地震工程术语。
震源(Focus,Center or Hypocenter)：地壳深处岩层发生断裂、错动的地方称为震源。
震中(Epifocus or Epicenter)：震源在地表面上的垂直投影点，称为震中。
震中距(Epicenter Distance)：地面某点与震中之间的距离称为震中距。
等震线(Isoseismal Line)：对应于一次地震，在受到影响的区域内，根据地震烈度表对每一地点评定出一个烈度。烈度相同区域的外包线，称为等震线（或等烈度线）。
根据震源深度可以把地震分为浅源地震(Shallow focus earthquake)、中源地震(Intermediate focus earthquake)和深源地震(deep focus earthquake)。震源深度0—60公里为浅源地震，简称浅震。浅震对构筑物威胁最大。同级地震，震源越浅，破坏力越强。震源深度60—300公里为中源地震。震源深度300公里以上为深源地震。破坏性地震一般是浅源地震。如1976年的唐山地震的震源深度为8公里，2008年512汶川地震的震源深度14km，2011年日本311大地震的震源深度为海下10公里，1960年智利9.5级地震的震源深度33公里。
来源：建筑结构抗震，旨在传播结构抗震的思想、理论和技术，所发的文章均为原创，转载请注明出处。
