地震简问简答/What does an earthquake look like?

Q: What does an earthquake look like? 问：地震的仪表表象是怎样的？

A: In order to study earthquakes, scientists deploy seismometers to measure ground motion. Seismograms are recordings of ground motion as a function of time and are the basic data which seismologists use to study the waves generated by earthquakes. These data are used to study the earthquakes themselves and to learn more about the structure of the Earth.

答：为研究地震，科学家采用地震仪来记录大地运动。震动图是地震仪对大地运动的时间序列记录，同时也是科学家研究地震波的第一手资料。科学家以此既能研究地震，也能研究地球构造。

Seismologists generally describe earthquakes as local, regional, or teleseismic. These terms refer to distance from the earthquake to the recording instrument. Local events occur within the immediate area less than 100km away. Regional events occur within 10 - 1400km away. Teleseismic events are those which occur at great distances, greater than 1400km away. Local and regional earthquakes are dominated by crustal waves, i.e., by waves which propagate through the crust. At greater distances, the seismic wavefield is dominated by waves which sample the body of the earth - the upper mantle, the lower mantle, and the core.

通常，地震学家根据震中距地震仪的距离，把地震分为本地地震、区域性地震和远地地震三种。以地震仪所在地为圆心，本地地震发生在100公里以内的范围；区域性地震发生在10-1400公里以内的范围；远地地震发生在1400公里以外的范围。本地地震和区域性地震的地震波多为地壳波，即通过地壳传播的地震波；对于远地地震，其地震波则源自以上地幔、下地幔和地心构成的地球主体。

Earthquake examples: 三种震动图如下图所示：

Local or Near-field Earthquake 本地与近地地震

seismogram of local earthquake 本地地震的震动图

Regional Earthquake 区域性地震

seismogram of regional earthquake 区域性地震的震动图

Teleseismic or Distant Earthquake 远地地震

seismogram of distant earthquake 远地地震的震动图