Another year, and this old Earth is approaching the end of its six-hundred-million-mile lap around the sun. Soon, it will have performed three hundred and sixty-five rotations on its canted axis—not quite as many as it once managed (growth bands in corals tell us that, four hundred million years ago, there were four hundred and ten days in the year), but still a respectably brisk spin. Twice in each rotation, the rocky crust flexed up and down a few inches, its daily regimen of earth tides, the little-known counterparts of the oceanic variety.

In addition to these regularly scheduled exercises, the planet moved this year in other ways, some natural, some decidedly aberrant. Here is a look back at half a dozen notable ground-shifting events of 2015 and how they altered not only our landscapes but also our thinking about how Earth works.

1. Nepal Slides

We can be grateful that the planet spared us any tremors of magnitude 9.0 or greater, the so-called megathrust earthquakes that result from subduction, when one tectonic plate moves violently beneath another. As it was, a magnitude-8.3 subduction quake off the coast of Chile, in September, registered as the year’s largest but caused remarkably few confirmed deaths (thirteen). April’s devastating quake in Nepal, by contrast, killed nearly nine thousand people, even though it was less intense. This disparity underscores how capricious seismic energy can be, amplified not only by unstable bedrock but also frail economies.

Nepal’s extreme topography was certainly a primary reason for the destructiveness of the earthquake, which shoved a seventy-five-mile by thirty-five-mile block of crust about ten feet southward. Such events build mountains from within even as they contribute to their dismantling at the surface, a paradox that Charles Darwin first recognized when he witnessed a great earthquake in Chile on his voyage aboard H.M.S. Beagle. This spring, in the seconds after the fault slipped beneath Nepal, the resulting reverberations shook loose colossal volumes of rock in landslides. The scale of these avalanches, which surprised even geologists who study past cataclysms, lends credence to an emerging theory—that in mountainous areas, episodic landslides are the single most important mechanism of erosion, while rivers (previously thought to be the prime movers) just tidy up after them in the intervening decades and centuries. In other words, these landscapes may be shaped less by long periods of boredom than by short periods of terror.

2. Japan Shudders

A strange slow-motion earthquake was documented this year in the Nankai Trough, off the southeast coast of Japan, where the Philippine Sea Plate and the Eurasian Plate converge. In two separate instances, each lasting several days, seismometers on the ocean floor picked up very-low-frequency signals migrating along the upper part of this subduction zone. In contrast to typical earthquake ruptures, which unzip a fault at miles per second, these tremors propagated at the leisurely pace of twenty to thirty miles per day before falling silent.

Sluggish seismic events have been recorded before, emanating from the deeper parts of subducting plate boundaries. But the Nankai Trough episodes occurred in a shallow region. This is ominous because a series of near-surface slow-slip events is now known to have preceded the calamitous Tohoku earthquake, in 2011. (These were recognized only in retrospect, through re-analysis of noisy seismic records from the days before the disaster.) That quake, which occurred on Japan’s other notorious subduction zone, to the north, defied scientific expectations by rupturing even the shallowest part of the plate boundary, which in turn displaced an enormous volume of seawater and created a tsunami of greater amplitude than anyone had predicted. Signs of instability in the upper part of the Nankai zone have thus made Japanese seismologists understandably jittery, and they are keeping high-tech ears pressed to the ground, listening with urgency for the low, slow, secret song of the moving plates.

3. Oklahoma Shakes

Meanwhile, in Oklahoma, where earthquakes were once as rare as elephant’s eyes, more than seven hundred small to moderate temblors this year promise to earn the state the distinction of being the most seismically active in the Lower Forty-eight, denying California its long claim over that title for a second year running. There is little scientific doubt that the quakes in Oklahoma are being triggered by the injection, miles into the subsurface, of wastewater from oil and gas development. As an incompressible fluid, water at depth can more than hold its own against the crushing pressure of rock. It can prise open old cracks and reawaken long-dormant faults. This year, in a plot twist worthy of O. Henry, the clusters of induced earthquakes in Oklahoma were declared a national-security threat because of the danger they pose to some of the country’s largest stockpiles of fossil fuels.

4. California Sinks

As if being deposed by Oklahoma in the seismic rankings weren’t humiliation enough, California has been deflating this year as an indirect consequence of the persistent drought. NASA scientists reported in August that satellite-based radar measurements show parts of the San Joaquin Valley subsiding at more than an inch per month, as a result of increased groundwater withdrawal in response to the lack of rain. At the same time, the structural integrity of parts of the California Aqueduct, which carries water from the Sierra Nevada and Central Valley to the southern part of the state, may have been compromised by uneven changes in the underlying land, which has sagged as much as twelve inches in places.

5. Chesapeake Bay, Too

California’s depressed state is a recent affliction, but the Mid-Atlantic Region, and in particular the Chesapeake Bay area, has been suffering from chronic subsidence, undiagnosed until this year. In August, the U.S. Geological Survey released a study that sought to differentiate submersion related to climate change (the ocean rising) from variations in absolute elevation (the land falling). The bad news is that Chesapeake Bay is sinking faster than any other place on the East Coast, at a rate of about 0.07 inches per year. Factoring in the average rate of sea-level rise across the globe today, which is more than 0.12 inches per year, this could mean the loss of a vertical foot of coastline within fifty years.

The Bay’s foundering is a legacy of the Ice Age. Back then, the area lay just south of the glaciers’ edge. The weight of the ice was great enough to cause Earth’s upper mantle to flow out from under it, warping the land into what geophysicists call a forebulge, akin to the area around a person on a water bed. Now, twenty thousand years after the ice melted, the dislocated mantle is still moving back into place; areas that were once frozen over are slowly rising and the outboard bulges are collapsing. On the Baltic Coast of Finland, near the former center of the Scandinavian Ice Sheet, post-glacial rebound is so fast—at the breathtaking pace of several inches per year—that the country has laws specifying how to designate ownership over land that rises from the sea. For now, Chesapeake Bay landowners will be subject only to the laws of viscous flow.