PREM: Preliminary Reference Earth Model

The Preliminary reference Earth model (PREM) [Dziewonsky1981] is a one-dimensional model representing the average Earth properties as a function of planetary radius. The model includes the depth, density, seismic velocities, attenuation (Q) and anisotropic parameter (\(\eta\)) on the boundaries of several Earth layers. The data is loaded into pandas.DataFrame objects, which can be used to plot and make computations.

Out:

     radius   depth   density       Vpv  ...      Vsh  eta   Q_mu  Q_kappa
0    6371.0     0.0   1.02000   1.45000  ...  0.00000  1.0    0.0  57823.0
1    6370.0     1.0   1.02000   1.45000  ...  0.00000  1.0    0.0  57823.0
2    6369.0     2.0   1.02000   1.45000  ...  0.00000  1.0    0.0  57823.0
3    6368.0     3.0   1.02000   1.45000  ...  0.00000  1.0    0.0  57823.0
4    6368.0     3.0   2.60000   5.80000  ...  3.20000  1.0  600.0  57823.0
..      ...     ...       ...       ...  ...      ...  ...    ...      ...
194   400.0  5971.0  13.05366  11.23711  ...  3.65027  1.0   84.6   1327.7
195   300.0  6071.0  13.06890  11.24809  ...  3.65794  1.0   84.6   1327.7
196   200.0  6171.0  13.07979  11.25593  ...  3.66342  1.0   84.6   1327.7
197   100.0  6271.0  13.08632  11.26063  ...  3.66670  1.0   84.6   1327.7
198     0.0  6371.0  13.08850  11.26220  ...  3.66780  1.0   84.6   1327.7

[199 rows x 10 columns]

import rockhound as rh
import matplotlib.pyplot as plt

# Load PREM into a DataFrame
prem = rh.fetch_prem()
print(prem)

# Plot density and velocities
fig, axes = plt.subplots(1, 2, figsize=(9, 5), sharey=True)
fig.suptitle("PREM: Preliminary Reference Earth Model")
ax = axes[0]
prem.plot("density", "depth", legend=False, ax=ax)
ax.invert_yaxis()
ax.set_xlabel("Density [g/cm³]")
ax.set_ylabel("Depth [km]")
ax.grid()
ax = axes[1]
for velocity in ["Vpv", "Vph", "Vsv", "Vsh"]:
    prem.plot(velocity, "depth", legend=False, ax=ax, label=velocity)
ax.grid()
ax.legend()
ax.set_xlabel("Velocity [km/s]")
plt.show()