Axial Seamount is set on a long, low-lying plateau, with two large rift zones trending 50 km (31 mi) to the northeast and southwest of its center.

The volcano features an unusual rectangular caldera, and its flanks are pockmarked by fissures, vents, sheet flows, and pit craters up to 100 m (328 ft) deep; its geology is further complicated by its intersection with several smaller seamounts surrounding it.

Subsequent cruises and analysis showed that the volcano had generated lava flows up to 13 m (43 ft) thick, and the total eruptive volume was found to be 0.018–0.076 km3 (0.0043–0.0182 cu mi).

[6] Axial lies where the chain intersects with the Juan de Fuca Ridge,[7] approximately 480 km (298 mi) west of Oregon.

Although the exact nature of Axial Seamount remains unknown, its complex origins makes it one of the most geologically interesting features in the North Pacific.

Axial Seamount has two major volcanic rifts extending approximately 50 km (31 mi) north and south of its main summit, as well as several much smaller, ill-defined ones aligned in a roughly similar pattern.

Basins around the volcano increase its irregularity, making it unusually complex (most seamounts of roughly the same size are circular or flattened in shape.

[7] The northern rift zone of Axial Seamount is a 5 km (3 mi) long ridge running 10 to 20 degrees northeast of the main caldera.

The area contains high amounts of volcanic glass; a major eruption is still visible in the form of an elongated glassy lava flow extending off the caldera wall, east of the main rift line.

The largest of these is Brown Bear Seamount, to which it is connected[9] by a narrow ridge running roughly perpendicular to its western caldera wall.

Submersible dives with Pisces IV and DSV Alvin in 1983 and 1984 discovered the first active black smoker vents in the north Pacific.

[7] That same year, the National Oceanic and Atmospheric Administration (NOAA) founded its VENTS program, providing impetus for studying the volcano more closely.

[13] In May, a dedicated bathymetric survey of the seamount showed topographical changes along the volcano's southern flank, which estimated the thickest flows to 13 m (43 ft).

In July DSV Alvin made several dives on the seamount's summit caldera, followed in August through September by an extensive observation and collection program using ROV ROPOS, confirming the bathymetric estimates.

A sheet flow more than 3 km (2 mi) long and 500 to 800 m (1,640 to 2,625 ft) wide was produced from Axial Seamount's upper southern flank, on the site of what was formerly an active geothermal field.

In eight years Axial Seamount recovered approximately 50% of its 3.2 m (10.5 ft) of pre-eruption swelling, and in 2006, William Chadwick of the Oregon State University and his associates calculated that the next eruption would occur in approximately 2014:[14] Axial Seamount behaves in a more predictable way than many other volcanoes; likely due to its robust magma supply coupled with its thin crust, and its location on a mid-ocean ridge spreading center.

Although the instruments recorded hundreds of seismic events, only a handful had been noticed by SOSUS and land-based seismometers, as many components of the system had been offline at the time.

The volcano subsided by more than 2 m (7 ft) and produced a 2 km (1 mi) wide lava flow during the event, which was as much as three times larger than the 1998 eruption.

In a series of eight dives conducted by Pisces IV, the scientists discovered a vibrant hydrothermal vent community on the leading edge of a 300 m (984 ft) fissure within the caldera.

[16] Camera tows and submersible dives through the 1980s and 1990s revealed Axial Seamount's active state,[11] including the only known black smoker in the northwest Pacific.