P and S wave travel time inversions for subducting slab under the island arcs of the northwest Pacific

Journal Article · Thu May 10 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB05p06829· OSTI ID:5014729

Zhou, Hua-wei; Clayton, R W ^[1]

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1. California Inst. of Tech., Pasadena (United States)

The authors have observed slablike high P and S velocity anomalies around the Wadati-Benioff zone under island arcs of the northwest Pacific through travel time tomographic inversions. Nineteen years of International Seismological Centre travel time residuals for events and stations in this large region are used. Analyses of resolution and noise show that the images are generally well resolved. The images illustrate that slab anomalies are continuous along strike in most parts of the upper mantle of the region and become contorted and generally broadened with depth. Near the bottom of the upper mantle, fingering of the slabs, including segmenting and spreading, is indicated. The fast anomalies associated with the Japan, Izu-Bonin, and Mariana subduction zones tend to flatten to subhorizontal at depth, while downward spreading may occur under parts of the Mariana and Kurile arcs. The fast anomalies below 700 km are not in the shape of a single coherent sheet. The principal compressional axes of focal mechanisms in the region consistently follow the downdip direction of the high-velocity slab, even when it bends to subhorizontal at depth. The depth at which compression begins to dominate the downdip stress regime in the slab apparently depends on bending of the slab and its dip. Slab fingering and intense deep seismicity probably are the consequences of the slab encountering a barrier of some form around the 670-km discontinuity.

• OSTI ID: 5014729
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B5; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ASIA
BENIOFF ZONE
COMPRESSION
DATA ANALYSIS
DEPTH
DEVELOPED COUNTRIES
DIAGNOSTIC TECHNIQUES
DIMENSIONS
EARTH MANTLE
EUROPE
GEOLOGIC STRUCTURES
GEOLOGY
GEOMORPHOLOGY
ISLANDS
JAPAN
KURILE ISLANDS
MARIANA ISLANDS
NORTH AMERICA
PACIFIC OCEAN
SEAS
SEISMIC P WAVES
SEISMIC S WAVES
SEISMIC WAVES
SUBDUCTION ZONES
SURFACE WATERS
TOMOGRAPHY
TRUST TERRITORY OF THE PACIFIC ISLANDS
USA
USSR
WAVE PROPAGATION