Preliminary Reference Earth Model Dziewonski and Anderson 1981

Preliminary Reference Earth Model (Dziewonski and Anderson, 1981) 縦波（Ｐ波） 横波（Ｓ波） 地震パラメータ　Φ

PREM (P, , ) 7

The two types of seismic body waves are compressional waves (P-waves) and shear waves (Swaves). Both have speeds that are determined by the bulk modulus K, the shear modulus μ, and the density ρ0. The definition of the bulk modulus, is equivalent to 地震パラメター Seismic parameter Suppose a region at a distance r from the Earth's center can be considered a fluid in hydrostatic equilibrium, Also suppose that the compression is adiabatic (so thermal expansion does not contribute to density variations). The pressure P(r) varies with r as where g(r) is the gravitational acceleration at radius r. 1/ we get the Adams–Williamson equation: This equation can be integrated to obtain where r 0 is the radius at the Earth's surface and ρ0 is the density at the surface. g(r)

H, He, C, N, O Mg, Si, Fe 核マントル境界 135 GPa 3000 K 地球中心 365 GPa 6000 K 内核外核境界 330 GPa 5000 K 135 GPa and 3000 K at the core-mantle boundary, 330 GPa and ~5000 K at inner core-outer core boundary, 365 GPa and ~6000 K at the center of the Earth. 5