Constant velocity travel times

This example shows how to calculate the travel times of seismic waves in a constant velocity model. We first define the model and the source and receiver coordinates. We then calculate the travel times using the class :func:~covseisnet.travel_times.TravelTimes. Finally, we plot the travel times on a map.

import covseisnet as csn

Create a constant velocity model

We first create a constant velocity model with a velocity of 5 km/s. In order to do so, we simply need to define the geographical extent of the model, the resolution of the grid, and the velocity.

model = csn.velocity.VelocityModel(
    extent=(40, 41, 50, 51, 0, 20),
    shape=(20, 20, 20),
    velocity=3.5,
)

Calculate the travel times between the sources and the receiver

Each grid point of the model is considered as a source and the receiver is defined by the user. In the example below, the receiver is located at coordinates (40.7, 50.2, 0), somewhere in the model’s domain. The travel times are calculated using the class :class:~covseisnet.travel_times.TravelTimes.

We can then represent the travel times on a map using the method :func:~covseisnet.plot.grid3d.

# Calculate the travel times
traveltime = csn.travel_times.TravelTimes(
    model, receiver_coordinates=(40.7, 50.2, 0)
)

# Plot the traveltime grid
fig, ax = csn.plot.grid3d(
    traveltime,
    cmap="RdPu",
    label="Travel time (s)",
    vmin=0,
)