Fractal Dimension of a Trace as a Tool for First Arrival Picking
Esmat Pourjam, Hamid Reza Siahkoohi and Abdolreza Ghods
Institute of Geophtysics of Iran, Iran.
Contacts: Pourjam@yahoo.ca (Esmat Pourjam)
Abstract
Our eyes can recognize the arrival of the signal by comparing the recorded amplitude in various seismic traces. In this text we try to imitate this natural ability to find out a mathematical tool instead of eyes. Fractals are mathematical models, which are able to feel these changes. An algorithm is introduced for the automatic picking of seismic first arrivals. It detects the presence of a signal by analyzing the variation in fractal dimension along the trace. Among different methods, the ĊĊivider methodĦĤwas found to be the most suitable method for calculating the fractal dimension. A change in dimension was found to occur close to the transition from noise part of a trace to signal plus noise part of it, that is the first arrival. The nature of this change varies from trace to trace, but a detectable change is always found to occur. This algorithm is considerably slower than the other methods.
raeg2003@tansa.kumst.kyoto-u.ac.jp
Last modified: Fri Sep 20 14:59:18 2002