Global distribution and growth mechanisms of seamounts: Insights from statistical and tectonic analysis

Volcanic seamounts found in every ocean are among the most widespread landforms on Earth and their geological evolution provides valuable insights into Earth's interior melting processes. Seamounts form in diverse tectonic settings, including mid-ocean ridges, subduction zones, and intraplate volcanism, with their size and distribution reflecting their tectonic origin. Smaller seamounts typically form on younger seafloor near mid-ocean ridges, while larger seamounts originate from volcanism on older seafloor far from ridge axes. A common height threshold distinguishing small and large seamounts is 1-1.5 km. Using the latest gravity-predictive seamount census, we statistically analyzed 18400 well-surveyed seamounts, integrating geometric data (exposed height above the seafloor, radii, volume, and irregularity) and tectonic features (seafloor age, spreading rate, and hotspot proximity) from GEBCO_2024 and GPlates reconstructions.

Our analyses to date show that 90% of seamounts are under 2 km in height and distribute in all tectonic environments, whereas those above 2 km high are primarily located away from mid-ocean ridges. This height threshold may serve as a new criterion to distinguish small from large seamounts. Additionally, there are no fundamental differences in the distribution and shapes of seamounts across the Atlantic, Indian, and Pacific Oceans. Specifically, seamount height shows no strong correlation with spreading rate but a weak positive trend with seafloor age. Approximately one-third of seamounts in the three major oceans lie within hotspot tracks. Strikingly, nearly all seamounts taller than 4 km are associated with hotspots or large igneous provinces, exemplified by those situated on the "hotspot highway" in the western Pacific.

In a nutshell, seamounts generally grow to heights of up to 2 km regardless of formation setting, but growth to heights exceeding 4 km requires stronger impulse from hotspots or large igneous provinces. This finding suggests that towering seamounts worldwide are likely to be the product of anomalous magmatic activity caused by the upwelling of deep mantle plumes.