Method and apparatus for automatic monitoring of tectonic stresses and quantitative forecast of shallow earthquakes

An improved single fracture expansion probe for measuring and resolving lateral stresses in rock media surrounding a borehole, including:

• a central mandrel having an axial bore extending therethrough;
• a flexible, elastic expansion sleeve member surrounding said mandrel and inflatable by fluid pressure provided through said axial bore or deflatable by removal of fluid pressure through said axial bore;
• a pair of semi-cylindrical friction members secured about said expansion sleeve member and confronting along a datum plane, said datum plane extending through the axis of the mandrel and the lines of confrontation of said pair of semi-cylindrical friction members, whereby said expansion sleeve member inflates radially outwardly to fracture the borehole wall along a datum plane at a predetermined depth in the borehole;
• means for measuring diametrical changes of said expansion sleeve member from said datum plane during inflation and deflation operations of said probe;
• a pair of seal assemblies, each disposed between one of said end caps and a respective end of said expansion sleeve member, each seal assembly including an annular tapered body formed of elastic polymer;
• and,
• a plurality of internal anchor members embedded in said annular body of each seal assembly and extending generally parallel to the axis of said mandrel, each internal anchor member including a pair of generally cylindrical, disk-like members spaced apart axially and joined by a rod member extending generally axially therebetween.

A method for predicting shallow earthquakes by measuring and monitoring underground stresses surrounding an earthquake fault plane, comprising the steps of:

• drilling a plurality of boreholes in an array extending along and straddling the surface trace of an earthquake fault plane;
• installing a borehole probe assembly at a preselected depth in each borehole, each borehole probe assembly including expansion probes adapted to measure and resolve the lateral stress vectors in the rock media surrounding the probe assembly at said preselected depth;
• transmitting the lateral stress vector data from each borehole to a data collection center;
• compiling and processing the lateral stress vector data from all the borehole probe assemblies to determine the lateral stress vector field surrounding the earthquake fault plane;
• and,
• detecting lateral stress vector field anomalies indicative of an impending earthquake.