Local structural azimuth
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Local structural azimuth is used to estimate the local azimuth of seismic events. It contains three options which are Event, Gradient and Principal Component.
From figure 1, we can see the two limbs (A and B) of the anticline structure found in our seismic data. Limb A is blue in colour maybe dipping towards North-West at 300Ëš. Limb B is reddish yellow in colour maybe dipping towards South-East at 100Ëš.
The event is for the downslope azimuth [0, 360] of the estimated event. The gradient is assumed to be perpendicular to the event. Based on figure 3, it shows the downslope of the study area to be ranging from approximately 50Ëš to 300Ëš. The anticline part with its left limb is about 300Ëš and the right limb is about 100Ëš.
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The gradient, the azimuth [0, 360] of the instantaneous gradient of the sample neighborhood. From the figure 1 at Dip Attributes, we can see the anticline but not so clear. The azimuth based on the figure to be ranging from 175Ëš to 225Ëš. No other geological features are observed.
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The principle component, local azimuth estimate from principal component analysis of gradient covariance matrix. The azimuth direction shown in principle component is almost same with event azimuth but it can detect the anticline more effectively. The anticline can be clearly seen that its left limb is dipping towards north west direction and its right limb is dipping towards south east. By using different parameters in Sigma X, Y and Z, we observed that sigma X, Y and Z at value 1.5 gives the best resolution.