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Soil pressure coefficient considering earthquake by Mononobe-Okabe

Active soil pressure coefficient considering earthquake by Mononobe-Okabe can be obtained by following equation. (USACE EM 1110-2-2100 Appendix G)

\begin{equation} P_a=K_a\cdot (1-k_v)\cdot \left\{\cfrac{1}{2}\cdot \gamma_s\cdot d^2+q\cdot d\right\} \end{equation}
\begin{equation} K_a=\cfrac{\cos^2 (\phi-\alpha-\theta)}{ \cos\theta\cdot \cos^2\alpha\cdot \cos(\alpha+\delta+\theta)\cdot \left\{ 1+\sqrt{\cfrac{\sin(\phi+\delta)\cdot \sin(\phi-\beta-\theta)}{\cos(\alpha+\beta+\theta)\cdot \cos(\alpha-\beta)}} \right\}^2 } \end{equation}
\begin{equation} \theta=\tan^{-1}\left(\cfrac{k_h}{1-k_v}\right) \end{equation}
\begin{align} & P_a & & \text{active soil pressure} & \quad & K_a & & \text{active poil pressure coefficient} \\ & \gamma_s & & \text{unit weight of soil} & \quad & d & & \text{soil depth} \\ & q & & \text{surcharge load} & \quad & \phi & & \text{internal friction angle of soil} \\ & \alpha & & \text{gradient of wall surface} & \quad & \beta & & \text{gradient of ground surface} \\ & \delta & & \text{friction angle of wall surface} & \quad & \theta & & \text{seismic inertia angle} \\ & k_h & & \text{horizontal seismic coefficient} & \quad & k_v & & \text{vertical seismic coefficient} \end{align} 
import numpy as np

kh=0.077 # horizontal seismic coefficient
#kh=0 # horizontal seismic coefficient
kv=0 # vertical seismic coefficient
phi=np.radians(30.0) # internal friction angle of soil
alpha=0 # gradient of wall surface
beta=0 # gradient of ground surface
delta=0 # friction angle of wall surface
theta=np.arctan(kh/(1-kv)) # seismic inertia angle

c1=np.cos(phi-alpha-theta)
c2=np.cos(theta) * (np.cos(alpha))**2 * np.cos(alpha+delta+theta)
c3=1 + np.sqrt(np.sin(phi+delta) * np.sin(phi-beta-theta) / np.cos(alpha+beta+theta) / np.cos(alpha-beta))
Ka=c1**2/c2/c3**2

print(Ka)

Calculation results are shown below.

Ka=0.381 # earthquake (kh=0.077, kv=0)
Ka=0.333 # normal (kh=0, kv=0)

That's all. Thak you.