Ancient peoples’ beliefs about the world were reflected in their philosophies and religions. Icons and ideas generated at least three hundred years before the birth of Christ conceived the opposing yet inseparable yin and yang of Chinese philosophy. They are also expressed in the dual nature of the great Hindu god, Shiva — deity of both destruction and creation. India and China are not only home to these great traditions but occupy some of the most seismically active real estate on planet Earth. The earthquakes that have wracked that part of the world for eons cannot be classified as simply destructive or creative, as either good or bad, as a blessing or a curse — they are both.
There have been a number of great extinction events in the history of the planet, moments in time when life was pushed to the edge and almost beyond. The most well-known of these dire episodes brought an end to the age of dinosaurs, at the boundary between the Cretaceous and Triassic geologic periods—the K-T Mass Extinction (now officially termed the Cretaceous-Paleogene Extinction Event). Whether it was a comet or meteor, an object from space the size of Mt. Everest slammed into Earth some sixty-six million years ago, moving at close to thirty kilometers per second. The Chicxulub Crater, marking its impact and now buried under the Yucatan Peninsula and the Gulf of Mexico, is enormous—110 miles in diameter and twelve miles deep. Until recently it was thought that the impact alone and its immediate consequences (hurling tremendous amounts of debris into the atmosphere to block sunlight worldwide, changing the environment, killing plant-life, and inducing world-wide starvation) would have possessed sufficient clout to dethrone the titans who had ruled Earth for the prior 165 million years. That opinion has changed as of late. It seems much more likely that the dinosaurs were subjected to a savage double punch, a one-two knockout blow which even the likes of Tyrannosaurus rex couldn’t withstand. The real killer of the dinosaurs might have been seismic.
If nature abhors a vacuum, science detests coincidences, and sixty-six million years ago one of the greatest of them all was taking place: two global killing events occurring simultaneously. Something caused the crust of Earth to open—in India—and spew forth a mantle plume, a calamity thankfully rare in the extreme. A mantle plume is a colossal upwelling of abnormally hot rock that melts its way through the crust and discharges lava in volumes scarcely imaginable. A team of geophysicists from the University of Berkeley in 2015 published the newest and most accurate dates for the startlingly close timing of the asteroid impact and a particularly Homeric series of eruptions at a place known as the Deccan Traps. These eruptions ultimately covered 1.5 million square kilometers of the surface with lava. Untold trillions of tons of poisonous gases and noxious fumes accompanied this catastrophe for life. The newest evidence suggests that if the dinosaurs were knocked down by a meteor from space, the unlucky survivors were asphyxiated.
Geologists have a plausible connection between incredible blows striking from space and the resultant extrusion of molten death from the bowels of the planet: earthquakes. Certainly, the six-mile-wide asteroid that slammed into the Earth at 150 times the speed of a jetliner, energetically equal to a billion Hiroshima-sized explosions, caused earthquakes like none ever felt since. The cosmic punch would have rung the entire world like a bell. Dr. Michael Manga, a co-author of the Berkeley study, wrote that there would have been monumental tremors, everywhere, all over the planet, all at once. No one knows what causes mantle plumes but there are very credible hypotheses that wracking the entire world with magnitude 9.0 or greater earthquakes—everywhere—might do the trick. Team leader Mark Richards remarked that though the Deccan Traps had been erupting before the impact, weathering on terraces indicates that there had been a quiescent period prior to the Chixculub event and that the resulting seismic activity of the impact might have “changed the plumbing” and restarted the process, yet in a much more intensified way, accounting for the bulk of the eruptions. “This was an existing massive volcanic system that had been there probably several million years, and the impact gave this thing a shake and it mobilized a huge amount of magma over a short amount of time.”
It’s been posited that a similar asteroid strike and the resultant monumental mega-quakes may have preceded the opening of the Siberian Traps as well, causing a “Great Dying” unlike any before or since—the Permian Extinction, in which 90-95 percent of all species were killed. If an asteroid did strike Earth 250 million years ago—as has been suggested by evidence beneath the ice in Antarctica (Wilkes Land Crater) and in the Bedout High off the coast of Australia—it might have put into motion the same geologic disaster in Siberia, this one dwarfing the lava flows in India mentioned above. Here is an event lasting a million years that paved seven million square kilometers of Earth’s surface with lava and came within a hair’s breadth of terminating all life, pumping perhaps a billion tons of methane and four billion tons of sulfur dioxide into the atmosphere. All of the above, therefore, certainly makes sense of the “destruction” part of the Shiva-earthquake analogy. What about “creation,” however?
Dr. Eric Force is an esteemed professor of geosciences at the University of Arizona at Tucson and a retired United States Geological Survey (USGS) geologist. Professor Force has a unique and hard-to-dispute theory about how our civilized world came to form in its incipient stages. His contention is easily seen, for all Dr. Force has done is lay out two maps, one upon the other. The first is a chart of Earth’s tectonic plates and faults; the second is a map of ancient civilizations. They are almost identical. His hypothesis is that consciously or otherwise human settlement has favored fault zones due to the benefits provided by volcanic ash for farming, the up welling of useful materials to the surface, and ample water supplies that are usually found at plate boundaries. Professor Force’s apt observation connects seismicity with the rise of civilization, while the true nexus is actually far more important, exponentially more essential for the very existence of life on Earth. For when earthquakes cease to undulate across the surface of our planet, that will be the death knell for every living creature, barring none.
Earth’s continents, the very platform for all land-based life, owe their existence to seismicity and volcanism. They ride on massive broken chunks of Earth’s surface called tectonic plates and those plates in turn are impelled by the currents produced in the quasi-liquid ocean of semi-molten rock far below. The surface of our planet is not “terra firma”—it moves. Every year, every day, every moment it is in motion. Wrapped like a thin skin around the seething mass of magma that constitutes by far the bulk of our planet, the crust is twisted and contorted by titanic forces far below the surface. Superheated magma rises from Earth’s core and as it cools nearer to the surface it is subducted again, providing the motive force for the ceaseless tectonic treadmill, pulling back down into Earth’s mantle the heavier basaltic oceanic floors. This process is very much like the dynamics of the currents in the oceans or the atmosphere, except that the subterranean flow is composed of partially melted and plasticized solids and happens in slow motion. Since continental crust is composed primarily of lighter, silicon-rich, granitic materials, its buoyancy resists subduction and—thankfully for us—avoids the destructive fate of the ocean floors. Earth’s continents, and especially the amazingly durable three dozen or so cratons (the stable interior portions made up of ancient crystalline basement rock) from which they are composed, are particularly long-lived. They’ve been locking together, separating, and recombining over and over again for eons, drifting plates forcing adjoining plates to either slide over, slide under, or slide out of their way. Where plates meet and jostle for position is where colossal forces build up and explode; earthquakes are produced at these contested boundaries, called “faults.” It is only the positions of these deep fissures in the crust of Earth that have changed over the billions of years, being traced and then erased over the ages but one of the indelible signs of a planet with the requisite vigor and power to bear life.
The scorching heat of the planet’s core—almost as hot as the surface of the Sun—has been driving this process since the formation of Earth, four and a half billion years ago. In all that time the core has cooled by only about 5 percent. Heat generated by the radioactive decay of the stores of uranium, thorium, potassium-40, and other elements below the surface acts to slow down the cooling process. Since some of these isotopes have half-lives measured in the billions of years, there’s no imminent change in temperature on the horizon for the interior of the planet. Earth is geologically alive and will remain so into the foreseeable future. Without these seismic and volcanic processes to recycle vital materials and support complex chemical cycles, our planet would be converted from a fecund, verdant biosphere into a barren, dead rock.
When that tectonic engine finally ceases to operate, when earthquakes and volcanoes are a feature of Earth’s past, all life too will be expunged from the story. One need not detail the minutiae of the thousand catastrophes that would assail every form of life, since the greatest disaster is one that requires very little elaboration: the atmosphere and oceans will disappear. The Sun assails our biosphere constantly, blasting away atmospheric gases into space via the solar wind, but the planet is protected thanks to tectonics. Earth’s super-heated and spinning core generates a magnetic shield that minimizes the damage caused by the solar wind while volcanoes and biotic outgassing replace that which is lost. When those defenses vanish so does any chance for life. Once atmospheric pressure is nonexistent above the oceans, water will evaporate away at extremely reduced temperatures, be blown off into space, and Earth at end will someday look very much like Mars.
There’s every reason, then, for our understandably intense interest in earthquakes and to revisit the age-old question as to whether or not they might be forecast in some way. The dichotomy is that while we fear them, we need them. They bring buildings crashing to the ground, but our cement never would have existed but for those very temblors in the first place. Just as every breath of oxygen we take actually kills us—a little—so too is mankind inextricably intertwined with a force far, far greater than is easily fathomed, and which is terribly dangerous and yet bountifully life-giving at the same time.
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