TY - JOUR
T1 - Intraplate deformation in the Samoa-Gilbert-Ralik area
T2 - A prelude to a change of plate boundaries in the Southwest Pacific?
AU - Okal, Emile A.
AU - Woods, Dale F.
AU - Lay, Thorne
N1 - Funding Information:
The originalw ork on the Gilbert Islandss warm benefitedf rom discussionsw ith Hiroo Kanamori and Terry Wallace. The SEASAT data were ob-tamed and analyzedi n collaborationw ith Anny CazenaveT. he presenti deaso we much to discussion and exchangeo f data with Loren Kroenke and Dan Walker, during a visit of the first author to the Hawaii Institute of Geophysicsi n December 1984; finally, the Texas A & M Symposium provided an ideal forum for the discussiona nd refinemenot f the proposedm odel.C areful reviews by Seth Stein and Brann Johnson cont~butedt o improvingt he manuscript.P artial supporto f this researchb y the National ScienceF oundation,u n-der Grants E&R-83-05847a nd EAR-84-05040i s gratefully acknowledged.W e also thank the Donors of the PetroleumR esearchF und, adminis-teredb y the AmericanC hemicalS ociety,f or support of this researchu nder GranNt umber PRF-17294-AC2.
PY - 1986/12/15
Y1 - 1986/12/15
N2 - Intense intraplate seismic activity has recently been identified in the west-central Pacific, along a line extending from Samoa through the Gilbert Islands and the Ralik Fracture Zone to the Caroline Islands. Over the past 50 years, this seismic line has contributed an estimated 15-30% of the entire intraplate seismicity for the Pacific plate (Hawaii excepted). Focal mechanisms available for ten of the largest events during the 1981-1983 Gilbert Islands swarm, with horizontal compressional stress oriented at right angles to the direction of motion of the plate, cannot be reconciled with simple models of intraplate stresses. We speculate that they express large scale deformation of that part of the Pacific plate, related to incipient detachment of a microplate and relocation of the Pacific-Australian subduction zone some 1000 km to the north of its present position.
AB - Intense intraplate seismic activity has recently been identified in the west-central Pacific, along a line extending from Samoa through the Gilbert Islands and the Ralik Fracture Zone to the Caroline Islands. Over the past 50 years, this seismic line has contributed an estimated 15-30% of the entire intraplate seismicity for the Pacific plate (Hawaii excepted). Focal mechanisms available for ten of the largest events during the 1981-1983 Gilbert Islands swarm, with horizontal compressional stress oriented at right angles to the direction of motion of the plate, cannot be reconciled with simple models of intraplate stresses. We speculate that they express large scale deformation of that part of the Pacific plate, related to incipient detachment of a microplate and relocation of the Pacific-Australian subduction zone some 1000 km to the north of its present position.
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U2 - 10.1016/0040-1951(86)90025-9
DO - 10.1016/0040-1951(86)90025-9
M3 - Article
AN - SCOPUS:0022825152
SN - 0040-1951
VL - 132
SP - 69
EP - 77
JO - Tectonophysics
JF - Tectonophysics
IS - 1-3
ER -