The authors report that "calderas on five major volcanoes on Mars have undergone repeated activation and resurfacing during the last 20 per cent of martian history, with phases of activity as young as two million years, suggesting that the volcanoes are potentially still active today." They also state that "glacial deposits at the base of the Olympus Mons escarpment show evidence for repeated phases of activity as recently as about four million years ago," but do not describe any observed eruptions within the last century or assign any Volcanic Explosivity Index (VEI) values.

Earth has volcanoes — and Mars has volcanoes. Earth has actively erupting volcanoes — and Mars has... none. No one has ever seen a Mars volcano erupt, yet scientists can look at the results of past eruptions and make calculations and predictions.

Olympus Mons is a massive shield volcano on Mars. There are no historical eruptions because no volcanism on Mars has been observed in modern times. Age dating of lava flows suggests activity into geologically recent times (tens of millions of years ago), but there is no record of eruptions in the last century.

NASA’s fact page on Olympus Mons describes it as a massive shield volcano and the tallest planetary mountain in the solar system. It explains that crater-count dating suggests Olympus Mons was volcanically active well into the geologically recent past, possibly as recently as tens of millions of years ago, but does not report any eruptions in human history or in the last century. As a shield volcano, its activity is described as dominantly effusive lava flows rather than highly explosive VEI 8 eruptions.

ESA summarizes Mars Express results, noting that Olympus Mons and other Tharsis volcanoes "have been active much more recently than previously supposed." It reports that their central calderas "appeared to have been resurfaced within the last 20 million years, with the possibility of lava emanating from several small vents as recently as two million years ago" and that activity in the summit calderas was clustered around 100–200 million years ago. The article describes these volcanoes as currently dormant and says nothing about instrumentally recorded eruptions in the last 100 years or any VEI estimates.

The USGS geologic report states that within the past 100 million years, "a series of collapse events and lava eruptions at the summit of Olympus Mons produced the volcano's caldera complex of nested craters." It further notes that Amazonian eruptions deposited volcanic rocks in the Olympus Mons region and that the Amazonian Period was geologically active, but the timescales discussed are millions to hundreds of millions of years. The document does not refer to any eruptions observed or recorded over the last century, nor does it provide VEI classifications for specific Olympus Mons eruptions.

A compiled abstract on Olympus Mons notes: "Crater retention ages on the volcanos Arsia Mons, Olympus Mons, and Pavonis Mons indicate significant volcanic activity in the last 100-200 million years." It continues: "We find that effusive eruptions have dominated volcanic activity on Olympus Mons in the Late Amazonian. Explosive eruptions were rare, implying volatile-poor magmas and/or a lack of magma-water interactions during the Late Amazonian." The time frame is hundreds of millions of years, not the last century, and explosive events are described as rare rather than frequent VEI 8 eruptions.

In a FAQ on Martian volcanoes, NASA describes Olympus Mons as dormant and notes that its most recent eruptions are thought to have occurred tens of millions of years ago based on the low number of impact craters on its flanks. The FAQ emphasizes that there have been no observed eruptions of Olympus Mons during the era of spacecraft observations and that any activity would be inferred from geological dating rather than recorded eruptions in the last century.

Recent studies of Martian volcanic plains suggest that some lava flows may be as young as a few million years old. Our analysis of craters superposed on the youngest lava flows in the Cerberus Fossae region indicates eruption ages of 2 to 10 million years. These results imply that Mars has experienced relatively recent volcanism, but the timescales are millions of years and the work does not identify any historically recorded eruptions in the last century or VEI 8 "super-eruptions" on Olympus Mons.

Scientists found evidence that a region of northern Mars called Arabia Terra experienced thousands of 'super eruptions,' the biggest volcanic eruptions known, over a 500-million-year period about 4 billion years ago. Spewing water vapor, carbon dioxide, and sulfur dioxide into the air, these explosions tore through the Martian surface. Arabia Terra so far has the only evidence of explosive volcanoes on Mars, indicating that these enormous explosive eruptions are not associated with Olympus Mons but with a different region.

Mars' Olympus Mons is the largest volcano in the solar system. When compared to Martian terrain in general, there aren't many impact craters on Olympus Mons' surface. This indicates that the uppermost layer of lava is relatively young, with the last eruption occurring as recently as 25 million years ago. This raises the intriguing possibility that the volcano is still active, and may erupt again in the future.

The article notes: "Olympus Mons is not erupting now, and hasn't erupted throughout the Space Age, i.e. in the time that humans have been sending rovers and probes to investigate Mars. That means there are no images of Olympus Mons erupting." It further states that astronomers estimate the most recent **large volcanic eruption** occurred about 25 million years ago, emphasizing that activity is ancient on human timescales and not something recorded over the last century.

This reference entry describes Olympus Mons as a massive shield volcano on Mars and the tallest mountain in the solar system. It notes: "Despite the fact that Olympus Mons has not erupted in millions of years, scientists believe the volcano may still be active." Later it reiterates that its last eruption is "thought to have been only about twenty-five million years ago," which is considered recent in geological terms but far older than the last century. No recent or observed eruptions are reported.

Reporting on a 2026 Geology paper, EarthSky notes that a study of a volcanic system south of Pavonis Mons found that "even during Mars' most recent volcanic period, magma systems beneath the surface remained active and complex" and that the system "did not erupt just once; it evolved over time." The article discusses multiple eruptions in Mars' geologic past and suggests some volcanoes were active relatively recently in geological terms, but it does not claim any confirmed eruptions on Mars in the last century and does not mention Olympus Mons eruptions or VEI values.

A massive shield volcano, Olympus Mons was built by the multitude of lava flows that cascaded down its sloped surface over billions of years. Its low profile and broad, gently sloping flanks are characteristic of shield volcanoes, which are typically fed by long-lived, relatively nonexplosive eruptions of fluid lava rather than short-lived, highly explosive eruptions.

NASA’s Mars facts page notes that the planet hosts giant shield volcanoes including Olympus Mons and that these volcanoes were built by repeated eruptions over billions of years. It explains that crater counts and other geological methods indicate that Martian volcanic activity continued into relatively recent geologic times but are "millions of years" in the past. The overview does not list any modern recorded eruptions on Mars and contains no mention of VEI or specific Olympus Mons eruptions in the last 100 years.

A solution discussing common misconceptions about Olympus Mons explicitly addresses a similar claim. It states: "No recorded eruptions of Olympus Mons in the last century. No evidence of eruptions with VEI 8 on Mars." It concludes that "Scientists consider Olympus Mons to be dormant or extinct, and no eruptions with a Volcanic Explosivity Index (VEI) of 8 have been documented on Mars. Therefore, the claim of five eruptions with VEI 8 in the past century is unsupported."

The Volcanic Explosivity Index (VEI) is an Earth-based logarithmic scale used to classify the explosiveness of volcanic eruptions, with VEI 8 representing extremely rare "mega-colossal" eruptions such as the Toba supereruption. Mars volcanoes, particularly Olympus Mons, are characterized in the scientific literature as predominantly effusive shield volcanoes, and there have been no direct observations or instrumental records of any Olympus Mons eruption since the beginning of telescopic and spacecraft monitoring, much less multiple VEI 8 events in the last 100 years.

The fact-check states: "No eruptions have been recorded in the last century. Surface lava flows date back approximately 2 to 25 million years ago, indicating the volcano is currently dormant." It further notes that "Shield volcanoes like Olympus Mons produce effusive lava flows with low explosivity, typically VEI ≤ 2. There is no record of any VEI 8 (super-eruption) events on Mars." This analysis directly addresses and corrects claims that Olympus Mons had recent eruptions with a Volcanic Explosivity Index (VEI) of 8, stating that such claims are inconsistent with current scientific knowledge.

The largest volcano in the solar system is Olympus Mons, located on Mars. Additionally, there is no record of five eruptions with a Volcanic Explosivity Index of 8, as Olympus Mons is considered a shield volcano with a history of less explosive eruptions. The statement 'Over the last century, scientists have recorded five eruptions with a Volcanic Explosivity Index of 8' is presented as an incorrect option in the problem discussion.