Tectonic Plates, Earthquakes, and Volcanos

Yesterday (April 5, 2018) there was a magnitude 5.3 earthquake off the coast of California near Los Angeles. No serious damage resulted, but scientists say there is a one-in-twenty chance that quake could be the foreshock of a larger quake. This brings up the question of why we have earthquakes. Did God do a poor job of designing the Earth?

The answer to that question is, “No.” Earthquakes result from factors that are essential for life on Earth. Earth’s crust consists of tectonic plates floating on the mantle, which is a region of molten rock. Under the continents, the Earth’s crust averages 18 miles (30 km) thick. Under the oceans, the crust is only about 3 miles (5 km) thick. The mass of the crust puts great pressure on the molten rock in the mantle causing it to be very viscous. If a crack opens in the crust, the molten rock will move upward, become more liquid as it is under less pressure. Then it may burst from the surface creating a volcano.

Volcanoes create mountains, and so does the movement of the tectonic plates. The tectonic plates moving against each other also produce earthquakes. Sometimes the plates will move against each other horizontally. We call that a slip-strike earthquake and that is what happens in the San Andreas fault in California. The quake that just occurred was a thrust quake where one side of a fault thrusts over the top of the one next to it. The Rocky Mountains and the Himalayas were pushed up by movement of the tectonic plates.

By the creation of mountains, the Earth has been continuously renewed. On the surface of the continents, erosion, and weathering break up solid rock to produce sand, clay, and ultimately topsoil. Erosion cuts down the mountains and deposits sediment in the lower elevations. Further erosion carries the sediment out into the oceans. In the deepest parts of the ocean, there are trenches. Huge amounts of sediment settle into those trenches, but they never get full. That’s because the sediment sliding into the trenches is finding its way down into the mantle.

The movement of sediment replenishes the mantle with new material which then resupplies the continents with new rock. Volcanoes erupt bringing recycled minerals and nutrients to the surface. Volcanic soils are the richest soils on Earth. This system has also brought the iron and other essential minerals into the Earth’s crust.

This is a greatly oversimplified explanation of the comprehensive recycling system that God designed into the planet on which we live. Earthquakes and volcanoes are destructive when humans build homes and cities close to the fault lines and active volcano sites. But if the Earth’s recycling system didn’t exist, erosion would eventually reduce the land masses to sea level, and Earth would be a water world.
–Roland Earnst © 2018