Seamount abundances and Abyssal Hill Morphology on the eastern flank of the East Pacific Rise at 14°S

Bathymetric data from a Hydrosweep multibeam sonar survey of a 720 km long tectonic corridor on the east flank of the southern EPR at 14° 14‧S covered about 25,000 km² of zero-age to 8.5 m.y. old crust (magnetic anomaly 4A). In this corridor we document a strong correlation of robust along flowline changes in abyssal hill morphology and seamount size distribution with spreading rate changes deduced from our magnetic data. Indeed, we find that both rms height of abyssal hills and abundance and height of seamounts increase significantly as spreading rate changes from ∼ 75 mm/yr to over 85 mm/yr (half rate). Moreover, we identified 46 seamounts taller than 100 m. Previous studies on the southern EPR reported a larger density of seamounts, organized primarily in chains. Our investigation, however, revealed seamounts not associated with major chains, leading us to the conclusion that different forms of off-axis volcanism occur along the spreading center.