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When slabs collide; a tectonic assessment of deep earthquakes in the Tonga-Vanuatu region

Simon Richards, Robert Holm and Grace Barber
When slabs collide; a tectonic assessment of deep earthquakes in the Tonga-Vanuatu region
Geology (Boulder) (August 2011) 39 (8): 787-790

Abstract

An unusual group of more than 100 earthquakes is located approximately 600 km beneath the North Fiji Basin in the southwest Pacific Ocean. These earthquakes are attributed to seismicity within detached segments of the subducted Australian plate. One of these detached slab segments has collided with, and now impinges on, the subducted Pacific plate at a depth of approximately 500 km. The region in the mantle where the two slab segments meet is also characterized by an unparalleled abundance of large-magnitude (Mw >7.0) earthquakes for this depth. The folded shape of the Pacific slab beneath Fiji, as well as the abundance of earthquakes, is interpreted to result from deformation and deformation-enhanced phase transformations as the two slabs collide and settle on the 660 km discontinuity. Detachment of the slab segments is interpreted to have occurred at ca. 5 Ma, but collision between the eastern segment and the west-dipping Pacific slab is interpreted to have occurred at ca. 4 Ma, coincident with initial opening of the overriding Lau Basin.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 39
Serial Issue: 8
Title: When slabs collide; a tectonic assessment of deep earthquakes in the Tonga-Vanuatu region
Affiliation: James Cook University, School of Earth and Environmental Sciences, Townsville, Queensl., Australia
Pages: 787-790
Published: 201108
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 31
Accession Number: 2011-069076
Categories: Solid-earth geophysicsSeismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: sects., sketch maps
S23°00'00" - S15°00'00", W177°00'00" - W171°00'00"
S20°30'00" - S13°00'00", E166°00'00" - E169°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201138
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