Mount Everest Is Still Growing — Here's the Tectonic Force Behind It

Mountaineers who summit Mount Everest today are standing slightly higher than those who reached the top a century ago. Not by much — roughly 4 millimeters per year, accumulating to about 40 centimeters over a century — but the movement is real, measurable, and driven by one of the most powerful geological processes on Earth. The mountain that appears fixed and eternal on every map of the world is, in geological terms, still being built.

The mechanism behind Everest's ongoing growth is plate tectonics. Earth's surface is divided into a dozen major lithospheric plates that move relative to one another at speeds of a few centimeters per year — roughly the same rate your fingernails grow. The Indian Plate, carrying the Indian subcontinent, is pushing northward into the Eurasian Plate at approximately 5 centimeters per year. This collision, which began around 50 million years ago, is what created the entire Himalayan range in the first place.

The Collision That Built the Himalayas

Before the collision, the region that is now South Asia was a separate landmass called the Indian Plate, drifting northward across what was then the Tethys Sea. As it approached and eventually collided with the Eurasian Plate, two things happened simultaneously: the seafloor sediments of the Tethys were pushed upward, and the crust of both plates crumpled under the force of impact. That crumpling formed the Himalayas, with Everest — technically the highest point of this ongoing crustal compression — reaching its current height of 8,848.86 meters (29,031.7 feet) as officially measured by a joint Chinese-Nepali survey in 2020.

The upward push continues today because the Indian Plate has not stopped moving. Each year, as it drives further beneath the Eurasian Plate in a process called subduction, the material above is compressed and forced upward. The net result is approximately 4 millimeters of additional height added to Everest annually. This figure varies depending on how it is measured and what correction factors are applied — erosion, for instance, works against the uplift, and major earthquakes can cause sudden and significant changes.

Earthquakes and Unexpected Drops

The 2015 Nepal earthquake, a magnitude 7.8 disaster that killed nearly 9,000 people, provides a dramatic illustration of how abruptly tectonics can change Everest's height. GPS measurements after the earthquake found that parts of the Himalayas shifted horizontally by up to 1.5 meters, and some peaks actually lost height as the seismic energy released built-up crustal stress. Everest itself was measured by different teams with results that differed by a few centimeters, illustrating the challenge of measuring a moving target in an actively deforming landscape.

The 2020 remeasurement of Everest — a joint expedition involving both Nepali surveyors using GPS and Chinese teams using radar — produced the most precise figure yet. The revision increased the official height by about 86 centimeters compared to the previous 1999 measurement, a change that incorporates advances in measurement technology as well as actual geological change. Separating the "we measured it better" component from the "the mountain genuinely grew" component is one of the more interesting technical challenges in modern geodesy.

A Mountain That Defies Permanence

There is something philosophically compelling about the world's highest mountain being a temporary feature of a temporary landscape. In geological time, the Himalayas are young — barely 50 million years old, compared to mountains like the Appalachians in North America, which are over 480 million years old and have been heavily worn down by erosion. Everest's reign as Earth's highest point is not guaranteed even on geological timescales. Erosion, future plate movements, and the ongoing dynamics of the Indian-Eurasian collision will continue reshaping the landscape for hundreds of millions of years.

For now, though, Everest keeps growing — 4 millimeters at a time, one year at a time, in a process so slow it is invisible to any human observer yet so powerful it has reshaped half a continent.