1. Reprocessing of Legacy Seismic Reflection Profile Data and Its Implications for Plate Flexure in the Vicinity of the Hawaiian Islands.
- Author
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Cilli, P., Watts, A. B., Boston, B., and Shillington, D. J.
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SEISMIC reflection method , *FLEXURE , *ELASTIC plates & shells , *PLATE tectonics , *GEOPHONE , *RHEOLOGY - Abstract
During 1975–1988, an academic research ship, R/V Robert D. Conrad, acquired more than 150,000‐line‐km of multichannel seismic reflection profile data from each of the world's main ocean basins and their margins. This extensive legacy seismic data set, which involved both single ship and two‐ship data acquisition, has been widely used by the marine geoscience community. We report on our experience in reprocessing seismic reflection profile data acquired during Conrad cruise RC2308 to the Hawaiian Islands region in August/September 1982. We show that the application of modern, industry standard processing techniques, including filtering, de‐bubble, deconvolution, and migration, can significantly enhance 40+ year old legacy seismic reflection profile data. The reprocessed data reveals more precisely, and with much less scatter, the flexure of Cretaceous Pacific oceanic crust caused by the Pliocene‐Recent volcanic loads that comprise the Hawaiian Islands. A comparison of observed picks of top oceanic crust which has been corrected for the Hawaiian swell and the Molokai Fracture Zone with the calculations of a simple 3‐dimensional elastic plate (flexure) model reveals a best fit elastic plate thickness of the lithosphere, Te, of 26.7 km, an average infill density of 2,701 kg m−3, and a Root Mean Square difference between observations and calculations of 305 m. Tests show these results depend weakly on the load density assumed and that the average infill density is close to what would be predicted from an arithmetic average of the flanking moat infill density and the infill density that immediately underlies the volcanic edifice. Plain Language Summary: The mid‐1970s to mid‐1980s saw a rapid increase in the acquisition of marine seismic reflection profile data by academic research vessels using large airgun arrays and long multichannel streamers. The data have provided some of the best images we have of the structure of mid‐ocean ridges, transform faults and fracture zones, and deep‐sea trenches; however, the processing of these data was rudimentary in comparison to modern standards. We show here how reprocessing of seismic reflection profile data acquired some 40+ years ago in the vicinity of the Hawaiian Islands that utilize modern methods of filtering, deconvolution, and migration technologies have significantly improved imaging of the top and bottom of oceanic crust, reducing the scatter in reflector depths from a legacy data set by almost a factor of two. This, in turn, has led to improved resolution of the large‐scale deformation caused by the individual volcano loads that comprise the Hawaiian Islands and, since the ages of these loads and the ocean floor on which these loads have been emplaced are known, to a better understanding of the stress state, strength, and rheological properties of Earth's tectonic plates. Key Points: Modern methods of deconvolution and migration technologies have significantly enhanced the value of a 40+ year seismic data setReprocessing of legacy seismic data acquired at Hawaii provide the best examples we have of plate flexure caused by volcano loadingCurrent difficulties in mounting new seismic experiments at sea require the reprocessing of legacy seismic data sets using modern methods [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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