Stress Transfer Theory VI

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     The release of accumulated stress at a particular point during an earthquake alters the shear and normal stresses along the tectonic plate boundary and surrounding fault lines. According to geophysical theory, the Coulomb Failure Stress Change, which is the estimated alteration and resultant transfer of shear and normal stresses along a plate margin, is a function of change in shear stress along a fault and secondarily the change in normal stress along a fault and the change in pore pressure in the fault zone, the latter two factors scaling according to the friction coefficient characteristic to the plate margin.
     By measuring and calculating the stress transfer following seismic activity, it is possible to subsequently construct basic contour maps of regions where there have been positive stress changes and are therefore of higher risk of being potential epicenters of future large earthquakes. Calculations have revealed that when an earthquake occurs, approximately 80% of the energy is released as seismic waves, whereas the remaining 20% is stored and transferred to different locations along the fault, making those specific regions more susceptible to future earthquakes.
     Predicting earthquakes by using the theory of stress transfer has important potential applications. The main rival technique for forecasting, the statistical analysis of patterns in seismic activity, suffers from a contradiction. Foreshocks are deemed evidence of the potential for a future high-magnitude earthquake, but the lack of foreshocks along faults known to be active has been considered an equally plausible potential precursor for large events.
     The stress transfer theory has been used to predict the location of a magnitude 7.4 earthquake that occurred two years later in the port city of Izmit, Turkey, killing more than 30,000 people. A limitation of the theory as currently applied, due to insufficient understanding of plate kinematics, is that refining predictions with temporal constraints appears to be far more problematic; the team that gave the Izmit prediction had forecast an event near the city within thirty years.

The theory described in the highlighted text relates to the prediction techniques discussed in the passage in which of the following ways?

It provides a theoretical basis of tectonic activity that is applied in one of the prediction methods discussed.

It suggests that since foreshocks are evidence of future seismic activity, but not definitive evidence, the two prediction methods should be used jointly.

It suggests that there may not be enough certainty inherent to plate kinematics to enable the development of a reliable prediction method.

It corrects existing theories about the transfer of tectonic stress, and thus provides a basis for correcting current prediction methods.

It suggests that simple prediction methods have a higher success rate in the than do more recently developed methods.

Review: Stress Transfer Theory VI

Explanation

This passage asks us about the theory described in lines 4-13, which we glossed over in our reading of the passage. We know that the theory is a scientific description of facts that make the stress transfer prediction method possible; this much can be inferred from the context without understanding all the details of the science. If we are fortunate, we might be able to answer this question with just that knowledge: "science behind stress transfer prediction method." Choice (A) matches that notion fairly well, so we can keep it for now. Choices (B) through (E) all fail to match our basic understanding. Another simple way to answer this question is to recall that opinion does not enter the passage until the third paragraph, so the correct answer to this question will most likely be opinion-neutral, while (B) through (E) are all moderate or heavy in expressing opinion.

The correct answer is (A).

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Stress Transfer Theory VI