Three-dimensional calculations of fault zone guided waves
in various irregular structures
Gunnar Jahnke, Heiner Igel, Yehuda Ben-Zion
This archive contains additional information to the paper, e.g. snapshot movies of selected models.
- Basic Fault Model
The Reference fault model.
This model shows the characteristic FZ-wave properties for a double couple source orientated in xy-direction. The source is located at the left FZ boundary.The snapshot on the left (and all subsequent snapshots) show the xz-plane of the model and the y-component of velocity of the seismic wave field. This plane is a nodal plane for P waves, thus only S wave energy is visible in all snapshots shown here.The dark rectangle corresponds to the fault zone with reduced seismic velocities. Blue and red colors denote positive and negative polarization of the wave field.Note that the absorbing boundaries lead to a vanishing wave field near the edges of the model.See the Movie for a time evolution of the wave field and the Seismogram plots for wave forms and spectra.
- Fault With Lateral Disruption
Fault with Lateral Disruption of 1 FZ-width.
A lateral shift of up to 1 FZ-width permits enough FZ wave energy to move from the lower to the upper FZ segment to be clearly visible in the seismograms.While crossing the depth of disruption some trapped energy radiates like a point source into the surrounding quarterspaces. This energy is clearly visible in the seismograms as a phase arriving right before the FZ waves and visible across the whole receiver line.
- Fault With Bottle Neck
Fault with a Bottle Neck with 6 2/3 FZ-widths vertical extension.
The source is located at the left FZ boundary. Passing the bottle neck region, a certain amount of trapped energy radiates into the surrounding quarterspaces.Most of the FZ energy is capable of trespassing the narrow part moderately changing it's wave form and amplitude.Due to the stronger dispersion in the narrow part, the resulting wave field is somewhat more complex.
- Shallow Fault Structure
Shallow Fault with a source located beneath the FZ.
Due to the source location in the underlying homogeneous half space, the source firstly radiates body waves with spherical wave fronts.Some fraction of the direct S-wave enters the FZ and transforms into a FZ wave.
- Fault With Small Scale
Fault With Small Scale Heterogeneities.
While the FZ-wave travels through the fault, energy radiates into the surrounding quarter spaces.
However, the heterogeneities are not capable to destroy the FZ wave train which leads to clear FZ arrivals in the seismograms.