When we pluck a string fixed at both ends, then this will creating a standing wave. We can get some insights on the behavior of the propagating wave by considering normal modes or free oscillations of the string. A wave propagating along the string follows the 1D scalar wave equation. Since, the string has fixed... Continue Reading →

# Modeling a wave on a string using finite differences

Based on problem 3.7 chapter 3 of Introduction to Seismology (Shearer) (COMPUTER) In the case of plane-wave propagation in the x direction within a uniform medium, the homogeneous momentum equation (3.9) for shear waves can be expressed as ,where u is the displacement. Write a computer program that uses finite differences to solve this equation... Continue Reading →

# Calculating Pressure and Tension axis given the fault plane (strike, dip and rake): Analytical solution

The fault plane is characterized by its normal vector and the direction of its motion is given by the slip vector. Here, we calculate the normal vector and the slip vector for a given fault geometry. The orientation of the normal vector and the slip vector is given in a geographical coordinate system with x... Continue Reading →

# Calculating Auxiliary Fault Plane Solutions given the main fault (Fortran)

We have calculated the auxiliary fault plane solution using the input of main fault solution in perl. Here, we do the same in Fortran. And we will also plot to solution to visualize the results. Fortran Code to get the auxiliary fault plane solutions: program auxiliary_fault_plane ! Program to calculate the strike, dip and rake... Continue Reading →

# Travel time curve calculation for spherical, isotropic, homogeneous Earth model

A travel time curve is a graph of the time it takes a seismic ray to reach the station from an earthquake versus the distance of the earthquake to the station (epicentral distance). Here, we calculate the travel time curve for a spherically homogeneous Earth. This means the seismic velocity is constant for the whole... Continue Reading →

# Simple Wave Plot (Fortran and Gnuplot demo)

We can use the power of Fortran to do computation of large data set and then we can use Gnuplot to visualize the results. Here, we take a simple example to see how we can do that. Let us take the first example, which we did using the MATLAB. We can do the similar calculation using... Continue Reading →

# Guessing a number (Fortran)

This program will randomly pick a value and the user is prompted to enter their guess. It will keep counting your number of attempts to reach the value stored by the system. The lower the number of guesses you have, the better guesser you are or your algorithm is better. To run the program: You... Continue Reading →