Chimborazo

Everest, at 8,848 metres, is the highest point above mean sea level.

Measured from the centre of the Earth instead, the summit of Chimborazo in Ecuador is farther out than the summit of Everest.

NOAA puts the gap at over 2,072 metres. Guinness World Records says more than 2 kilometres, and a 2019 Ecuadorian GNSS survey found 2,111.7 metres.

Guinness World Records puts Chimborazo's summit approximately 6,384 kilometres from the centre of the Earth.

Surveys give Chimborazo's height above sea level as between 6,263 and 6,270 metres: 6,263 metres from Ecuador's Geophysical Institute, 6,267.25 metres (give or take 5 centimetres) from the 2019 survey, 6,268 metres from NOAA and 6,270 metres from Guinness World Records.

That leaves Chimborazo about 2,600 metres lower than Everest when both are measured from sea level.

Mauna Kea in Hawaii is the tallest mountain from base to peak, rising more than 10,210 metres.

The Earth is not a perfect sphere. Its diameter bulges at the equator because of the centrifugal force created by its rotation.

NASA lists an equatorial radius of 6,378.137 kilometres and a polar radius of 6,356.752 kilometres, a difference of about 21 kilometres.

Earth's equatorial diameter is 12,756 kilometres.

NOAA puts Chimborazo about 1 degree south of the equator, where the bulge is greatest, and the Instituto Geofisico gives its latitude as 1.467 degrees south. Guinness World Records gives the distance as 158 kilometres.

Mountains and ocean trenches distort the planet's shape further, and gravity variations raise permanent hills and valleys of more than 300 feet (about 90 metres) in the ocean's surface.

Chimborazo stands 150 kilometres south of Quito and is the highest volcano of the northern Andes.

It is the southernmost volcano of the Cordillera Occidental and is built from three successive edifices. Its highest summit is called Whymper.

The volcano is about 20 kilometres across.

A sector collapse 60,000 to 65,000 years ago sent a debris avalanche over the plain around Riobamba. The deposit covers 280 square kilometres and averages 40 metres thick.

The most recent eruption is estimated to have happened between the 5th and the late 7th century, and the average interval between eruptions is about 1,000 years. That is why Chimborazo is classed as potentially active.

A glacier cap on the summit, steep flanks and closeness to Riobamba and Ambato give the volcano a high potential risk.

In 1870 to 1873, W. Reiss and A. Stübel determined the heights of Ecuador's main mountains by trigonometric methods.

A French-Ecuadorian geodetic mission in 2016 determined Chimborazo's distance from the centre of the Earth.

The 2019 survey placed Chimborazo 6,384,418.505 metres from the centre and Everest 6,382,306.772 metres, a difference of 2,111.733 metres.