Quartz weaknesses: Hosts Earthquake

Large concentrations of quartz — one of the most common minerals crust — can create it as a "weak point", which is easier to grow mountains and continents apart.

From the point of view of chemistry, quartz — surprisingly inert mineral, in pure form and in the other species (such as granite), it is up to 12% of the earth's crust. Quartz is found everywhere and in many different forms — from ordinary grains of sand to the semi-precious stones agate and amethyst. Moreover, the deeper mineral occurs, so it becomes softer and more "fluid" under the influence of all the growing temperature and pressure. In this sense, quartz — one of the "feeble" minerals. And recent studies have shown that an excess of it in different regions may be an important factor contributing to their tectonic mobility.

The work of US-British team of scientists analyzed the accumulated data on seismic activity in the western regions of the United States — first of all, on the motion of the primary waves (P-waves), the major earthquake precursors. Their propagation velocity scientists compared with the speed of the secondary S-waves that move slowly and carry most of the energy of a tectonic shift.

The scientists found that in all the regions where the crust exhibits significant stability (for example, in the east of the Rocky Mountains) P-waves travel at an average of 1.8 times faster than S-waves. However, where the crust is deformed — for example, in other areas of the Rocky Mountains or in the central Nevada — the ratio is lower. According to scientists, these figures correlate with the content of silica minerals in the cortex of the regions.

Besides the fact that the "mobility" quartz can explain the appearance of a lighter strain, it can cause deposits and the fact that at different times, in collisions and passing continents, faults occur over and over again on the same "weak" areas while others remain relatively stable. Containing large amounts of quartz regions, already stretched or squeezed by tectonic forces become more mobile, facilitating new strain: the process of an almost self-sustaining.

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