FRISK88M^TM operates on an ASCII text input file that requires you to define seismic sources and attenuation equations. Along with these definitions you must assign weights to each.

A pre-processor called PREP88 has also been developed to simplify complex input. When several weighted assumptions are included the input file can grow very quickly. With PREP88 much of the input file is automatically created. This reduces complexity as well as errors.

Seismic Source Definitions

FRISK88M^TM requires that you define faults and area sources. Faults are specified with the following parameters:

1. Fault trace (latitude-longitude)
2. Surface Dip Angle (degrees)
3. Listric Dip Angle (degrees)
4. Starting Depth (kilometers)
5. Listric Depth (kilometers)
6. Fault Depth (kilometers)
7. Slip rate/activity rate (mm/yr or number/yr)
8. Recurrence type (characteristic, exponential, combined)
9. Minimum magnitude
10. Maximum magnitude
11. Rupture length equation (RL = A + B*mag, km)

Again, most of these parameters can have multiple, weighted values and the program will process each.

An area source requires the following parameters:

1. Area boundary (latitude-longitude points)
2. Depth (kilometers)
3. Activity rate (number/yr)
4. Minimum magnitude
5. Maximum magnitude

Often activity rates and slip rates are derived from the analysis of earthquake catalogs. FRISK88M^TM does not provide the facilities to do this, but we are available to assist you in conducting the appropriate analyses.

Ground motion equations

FRISK88M^TM has a number of ground motion equation forms programmed into the software. The input file requires that the coefficients be assigned, so it is the user’s responsibility to determine the proper coefficients and usage of the equations. FRISK88M^TM is flexible, but does not provide any guidance in selecting sources or attenuation equations.