Sea-Floor Sunday #56: Samoa region in the South Pacific

This week’s Sea-Floor Sunday image is of the Samoa region in the South Pacific. Earlier this week (Sept 29, 2009) an 8.0 earthquake struck a couple hundred km south of the volcanic island chain.

See Chris Rowan’s post explaining this earthquake (and the nearly coincident, but unrelated, quake offshore Indonesia) here. Chris already showed some nice GoogleEarth images, so this one was made with the GeoMapApp tool.

map of Samoa region (made in GeoMapApp) showing epicenter of Sept 29, 2009 8.0 earthquake

Note the bathymetry color scale in upper left corner. The Samoan volcanic chain is related to large-scale lithospheric fractures in the Pacific Plate likely caused by interaction with the Tonga subduction zone.

Also check out this animation from NOAA showing the propagation of the tsunami triggered by this earthquake across the Pacific Ocean basin.

Finally, here’s a list of the coverage of the 2009 Samoan quake in the geoblogosphere:

• About.com — 8.0 Earthquake in Samoa
• Geotripper — Magnitude 8.0 Earthquake in Samoa
• NOVA Geoblog — Awesome: Samoa subduction cross-section
• Adventures in the World of Geology — Samoa Earthquake
• Highly Allochthonous — Two large earthquakes, two unusual focal mechanisms (linked to above)
• Chris Rowan of Highly Allochthonous also participated in an internet radio program on BBC — you can get the link to the audio here