Unlike many earthquakes, which develop along hidden faults beneath oceans or featureless plains, today's magnitude 7.8 quake in Nepal is easy to understand, even for the novice geologist. The Indian Subcontinent, which broke from Antarctica and Australia some 80 million years ago, has been plowing into southern Asia for the last 50 million years, crumpling up the Himalayas, the highest range of mountains on Earth.
The tectonic force responsible for this ongoing collision is sea floor spreading in the western Indian Ocean, triggered by mantle currents beneath the ocean crust. Inching to the NNE, India has fused with Asia and the intervening ocean crust is now incorporated within the mountain massif; indeed, Mt. Everest, the highest point on our planet, is capped with marine limestone.
Today's earthquake in Nepal, coupled with new eruptions of the Calbuco Volcano in southern Chile, remind us that the surface of our planet remains in flux, its tectonic plates rifting, colliding, subducting and scraping past one another. Driven by heat within Earth's core, this geologic process has continued for almost 4.6 billion years; we humans, having evolved less than 150,000 years ago, have come to understand plate tectonics but remain susceptible to its destructive force.
