With EZ-FRISK™, it is easy to set up a seismic hazard analysis. All you need to do is:
- Enter your site location (latitude and longitude).
- Let EZ-FRISK™ find all the faults and background source near your source.
- Select the attenuation equations to use with your sources.
Reasonable default choices have been provided for all other parameters. Unless you are dealing with
special cases, the default parameters provide a good engineering
tradeoff between accuracy and speed.
With EZ-FRISK™, it is easy to customize a seismic hazard analysis. You have the
flexibility to control the seismic hazard calculations. You can configure and turn on or off advanced analytic features such as:
- Deaggregation of hazard by distance, magnitude, and epsilon. The program lets you specify the
amplitude and period upon which to deaggregate.
- Near-source directivity effect. It allows you to study the average,
fault-normal, or fault-parallel components of the ground motion
according to the Somerville (1996) and Abrahamson (2000) provisions.
- Maximum rotated component effect. It allows you to calculate this component as required by some jurisdictions when using NGA equations. This calculation is based the Huang, Whittaker and Luco (2008) work.
These advanced techiques provide important information but unnecessarily
slow down routine calculations. We give you the choice whether or not to use them.
You can select individual seismic sources, select all sources within a specified distance,
or use a combination of both techniques. You can easily assign which attenuation equations
to use with a class of seismic sources (say fault sources, subduction zones, or gridded sources),
or assign particular attenuation equations to use with a specific source.
To refine your analysis you can override:
- Range of amplitudes to study (accelerations/velocities/displacements)
- Spectral periods (and PGA)
- Fractiles for deterministic analysis
- Attenuation equation site parameters such as shear wave velocity and depth to bedrock
- Integration parameters (see below)
During probabilistic seismic hazard analysis, the program generates a finite number of
earthquakes within the selected sources to approximate the possibility of an earthquake
occurring at any location with each source. The number and location of these events
can be controlled by user-defined integration increments.
- Magnitude integration step
- Horizontal incremental distance between ruptures
- Vertical incremental distance between ruptures
- Number of rupture lengths to satisfy rupture length uncertainty
- Incremental distance for hypocenters for near-source directivity
- Number of horizontal sections into which the area source is divided. The sections are arcs, concentric to the site, of variable length at a specific depth.
- Vertical distance between ruptures.
- Number of rupture azmuths.
- Number of rupture azmuths as a function of distance from site.
- Maximum distance from site to include hazard calculations.