Inversion of Large Electrical Resistivity Surveys on Multiprocessor Platforms

Abstract

Modern multi-channel resistivity instrumentation has facilitated an increased usage of electrical resistivity geophysical surveying over large and complex areas. Resistivity line lengths for near surface environmental problems commonly exceed a kilometer and 3D acquisition may be on the order of hectares. To evaluate the data through electrical resistivity inversion, however, the size of the model domain has been limited to very small problems based primarily on the memory allotment of the 32-bit Microsoft Windows-based operating systems. In this case, multiple small domains are required to model the large surveys. To overcome the domain-size limitation, the EarthImager3D code has been restructured to accommodate the latest Microsoft 64-bit operating systems (Windows Vista or Server 2003), with multiple processors and large computer memory availability. To demonstrate the increased capacity of the code, a field example is provided that shows the advantage of inverting data within a single domain compared to smaller multiple domains. The field data includes 47 lines of pole-pole resistivity profiles collected along parallel and orthogonal lines over a liquid waste disposal site in eastern Washington.