Hawaiian–Emperor seamount chain
The Hawaiian–Emperor seamount chain is the Hawaiian Islands and the Emperor Seamounts: together they form a vast underwater mountain region of islands, seamounts, atolls, shallows, banks and reefs. The line goes southeast to northwest beneath the northern Pacific Ocean; and many of the underwater mountains are guyots.[1]
The seamount chain, with over 80 identified undersea volcanoes, stretches over 5,800 kilometres (3,600 mi) from the Aleutian Trench in the far northwest Pacific to the Loʻihi seamount, the youngest volcano in the chain, which lies about 35 kilometres (22 mi) southeast of the Island of Hawaiʻi.
The oldest age for the Emperor Seamounts is 81 million years, and comes from Detroit Seamount. However, Meiji Guyot, located to the north of Detroit Seamount, is likely somewhat older.
In 1963, geologist John Tuzo Wilson explained that the Hawaiian-Emperor seamount chain was created by a hotspot of volcanic activity that stood as the Pacific tectonic plate moved over it. This left a trail of volcanic islands and seamounts. A "bend" or "V" in the chain marks a shift in the movement of the Pacific plate some 47 million years ago, from a northward to a more northwesterly direction. The bend shows how a tectonic plate can shift direction suddenly. A look at the USGS map on the origin of the Hawaiian Islands clearly shows this "spearpoint".[2]
Recent research shows that the hotspot itself may have moved with time. Some evidence comes from analysis of the orientation of the ancient magnetic field preserved by magnetite in ancient lava flows sampled at four seamounts.[3]
Emperor seamounts table
| Name | Type | Coordinates[4] | Age | Notes |
|---|---|---|---|---|
| Hancock | Seamount | 30°15′N 178°50′E / 30.250°N 178.833°E | 27.7 to 38.7 million | — |
| Colahan | Seamount | 31°15′N 176°0′E / 31.250°N 176.000°E | K-Ar 38.7±0.2 million[5] | — |
| Abbott | Seamount | 31°48′N 174°18′E / 31.800°N 174.300°E | K-Ar 41.5±0.3 million | — |
| Daikakuji | Seamount[6] | 32°5.00′N 172°18′E / 32.08333°N 172.300°E | K-Ar 42.4±2.3 and 46.7±0.1 million | Also the name of a Buddhist temple in Kyoto, Daikaku-ji |
| Kammu | Guyot[7] | 32°10′N 173°0′E / 32.167°N 173.000°E | 42.4 to 43.4 million | Named after Emperor Kammu, former ruler of Japan |
| Yūryaku | Guyot[8] | 32°40.20′N 172°16.20′E / 32.67000°N 172.27000°E | K-Ar 43.4±1.6 million | Named after Emperor Yūryaku, former ruler of Japan |
| Kimmei | Seamount[9] | 33°40.84′N 171°38.07′E / 33.68067°N 171.63450°E | K-Ar 39.9±1.2 and 47.9±0.2 million | Named after Emperor Kimmei, former ruler of Japan |
| Kōkō | Guyot[10] | 35°15.00′N 171°35.00′E / 35.25000°N 171.58333°E | K-Ar 48.1±0.8, 50.4±0.1 (south side), and 52.6±0.8 (north side) million | Named after Emperor Kōkō, former ruler of Japan |
| Ōjin | Guyot[11] | 37°58.20′N 170°22.80′E / 37.97000°N 170.38000°E | K-Ar 55.2±0.7 million | Named after Emperor Ōjin, former ruler of Japan |
| Jingū | Guyot[12] | 38°50′N 171°15′E / 38.833°N 171.250°E | K-Ar 55.4±0.9 million | Named after Empress Jingū, former ruler of Japan |
| Nintoku | Guyot[13] | 41°4.80′N 170°34.20′E / 41.08000°N 170.57000°E | K-Ar 56.2±0.6 million | Named after Emperor Nintoku, former ruler of Japan |
| Yōmei | Seamount[14] | 42°18′N 170°24′E / 42.300°N 170.400°E | 56.2 to 59.6 million | Named after Emperor Yōmei, former ruler of Japan |
| Suiko | Guyot[15] | 44°35′N 170°20′E / 44.583°N 170.333°E | K-Ar 59.6±0.6 (southern), 64.7±1.1 (central), and 60.9±0.3 million | Named after Empress Suiko, former ruler of Japan |
| Detroit | Guyot[16] | 51°28.80′N 167°36′E / 51.48000°N 167.600°E | ~ 81 million | Well-documented seamount, second-oldest |
| Meiji | Guyot[17] | 53°12′N 164°30′E / 53.200°N 164.500°E | 85 million | Named after Emperor Meiji, former ruler of Japan; oldest known seamount in the chain |
