Question: What volcano, with a height of nearly 22 km, is the reason scientist believe that the location of the poles of Mars have shifted?
Context: Olympus Mons ( ; Latin for Mount Olympus) is a very large shield volcano on the planet Mars.  By one measure, it has a height of nearly 22 km (13.6 mi or 72,000 ft).  Olympus Mons Nili Patera is a dune field on Mars.  It is located on top of a lava bed, at the site of an ancient volcano, the Nili Patera caldera of Syrtis Major, near the Martian equator, and it is one of the most active dune fields of Mars.  Its location coordinates on Mars are 8.7° N latitude, 67.3° E longitude.  It is being actively studied by the HiRISE camera, onboard the Mars Reconnaissance Orbiter, at the rate of one image every six weeks.  The study of the movement of the dunes provides information regarding wind variation as a function of time and furthers the study of surface erosion characteristics of the Martian landscape.  This information can then be used for the development and design of future Mars expeditions.  The dunes of the Patera field are of the barchan type and their study by HiRISE was the first one to establish dune and ripple movement of a minimum of 1 m on Mars.  The Patera dune field, was also the first to be investigated using the COSI-Corr software, which was originally developed to analyse the movement of earthbound dunes.  The research results from the evidence provided by the monitoring of the Nili Patera field, indicate sand fluxes of the order of several cubic metres per metre per year, similar to the flux observed at the sand dunes of Victoria Valley in Antarctica. Tweed Volcano is a partially eroded Early Miocene shield volcano located in northeastern New South Wales, which formed when this region of Australia passed over the East Australia hotspot around 23 million years ago.  Mount Warning, Lamington Plateau and the Border Ranges between New South Wales and Queensland are among the remnants of this volcano that was originally over 100 km in diameter and nearly twice the height of Mount Warning today, at 1156 m .  Despite its size, Tweed Volcano was not a supervolcano; other shield volcanoes - such as on Hawaii - are much larger.  In the 23 million years since the volcano was active, erosion has been extensive, forming a large erosion caldera around the volcanic plug of Mount Warning.  Its erosion caldera is the largest in the Southern Hemisphere. Didicas Volcano is an active volcanic island in the province of Cagayan in northern Philippines.  The island, which was a submarine volcano and re-emerged from the sea in 1952, is 22 km NE of Camiguin Island, one of the Babuyan Islands in Luzon Strait.  Before 1952, the volcano first breached the ocean surface in 1857. Isla Chañaral (sometimes referred to as Isla Chanaral or Chanaral Island) is located 6 km off-shore from the northern Central Chilean coast, some 100 km north of the city of La Serena.  Together with Isla Choros and Isla Damas, the island forms the Humboldt Penguin National Reserve, which is administered by the Chilean Forestry Corporation (CONAF).  All three islands support populations of Humboldt penguins, but are also habitat for several other rare and endangered animal species such as the Peruvian diving petrel or the South American marine otter.  In recent years the reserve has experienced a strong increase in tourist activities, mainly due to the presence of bottlenose dolphins that reside in the waters of the reserve.  However, recently local fishermen reported increasing spells of dolphin absence which scientist believe might be connected to disturbance from these largely unregulated activities. Las Lajas is a shield volcano located in the central part of Nicaragua, 22 km north of Lake Nicaragua.  Comarca las Lajas is among a number of communities lying within the volcano's caldera. For some time, scientists have thought that the location of the poles of Mars have shifted due to the great mass of volcanic material in the Tharsis dome which includes Olympus Mons, the highest volcano in the solar system.  A study published in Nature supports this idea. Albor Tholus is an extinct volcano in the volcanic province Elysium on Mars.  It lies south of the neighbouring volcanoes Elysium Mons and Hecates Tholus.  Albor Tholus is 4.5 kilometres high and has a diameter of 160 km at its base.  Its large caldera, having a diameter of 30 km and a depth of 3 km, is deep compared to calderas on the Earth.  The elevation of the lowest level of the caldera is the same as the base of the volcano; however, the original lower slopes of Albor Tholus may have been covered by lava flows from its larger neighbor, Elysium Mons.  Evaluations by the Mars probe Mars Express found that the volcanoes of the Elysium region were active over long periods. Alba Mons (formerly known as Alba Patera, a term that has since been restricted to the volcano's summit caldera) is an immense, low-lying volcano located in the northern Tharsis region of the planet Mars.  It is the largest volcano on Mars in terms of area, with volcanic flow fields that extend for at least 1350 km from its summit.  Although the volcano has a span comparable to that of the United States, it reaches an elevation of only 6.8 km at its highest point.  This is about one-third the height of Olympus Mons, the tallest volcano on the planet.  The flanks of Alba Mons have very gentle slopes.  The average slope along the volcano's northern (and steepest) flank is 0.5°, which is over five times lower than the slopes on the other large Tharsis volcanoes.  In broad profile, Alba Mons resembles a vast but barely raised welt on the planet's surface.  It is a unique volcanic structure with no counterpart on Earth or elsewhere on Mars. TW Hydrae b is a likely extrasolar planet orbiting the young T Tauri star TW Hydrae approximately 176 light-years (54 parsecs, or nearly km) away in the constellation of Hydra.  It is likely a Neptune-like planet orbiting at a distance of nearly 22 AU from its star.
Answer: Olympus Mons