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The Structure of the Oceanic Crust on the Northeast Hawaiian Arch imaged by Pre-Stack Depth Migration of Active-Source Seismic Data

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Title:The Structure of the Oceanic Crust on the Northeast Hawaiian Arch imaged by Pre-Stack Depth Migration of Active-Source Seismic Data
Authors:Nakrong, Nipaporn
Contributors:Moore, Gregory F. (advisor)
Geology and Geophysics (department)
Lower Crustal Dipping Reflection
Mohorovičić Discontinuity
NE Hawaiian Arch
Oceanic Crustal Thickness
show 2 morePre-Stack Depth Migration
Sub-Moho Event
show less
Date Issued:2019
Publisher:University of Hawai'i at Manoa
Abstract:The Northeast Hawaiian Arch off O‘ahu, formed by flexure of the Pacific Plate under the load of the Hawaiian volcanic island chain, is one of the regions under consideration for Integrated Ocean Drilling Program (IODP) drilling through the oceanic crust to the Mohorovičić discontinuity (Moho). Modern geophysical surveys in this area, including wide-angle seismic refraction data and multi-channel seismic reflection data (MCS), are insufficient for imaging the oceanic crustal structure and the Moho characteristics in order to define the potential drilling site. Therefore, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) carried out an active source 2-D seismic survey along the Hawaiian Arch using R/V Kairei in August and September 2017. One 750-km-long E-W reflection profile, shot perpendicular to abyssal hill (spreading) fabric, passes over five ocean bottom seismometers (OBS) with 150-km interval; three shorter N-S profiles were shot perpendicular to the long line at the OBS locations. We conducted pre-stack depth migration (PSDM) in an attempt to better image the Moho reflections than is possible with post-stack migration. The PSDM images confirm that the crustal thickness is approximately 5.4 km with a standard deviation of 0.3 km. Moho reflection is identified 50% of all lines, including shingled Moho (5%) and diffusive Moho (45%). Lower crustal dipping reflections (LCDRs) found at the east edge of Line E-W dip 5o to 12o toward the paleo-ridge axis and terminate at the Moho. These LCDRs may originate from a secondary shear zone due to active magma upwelling at the time of crustal accretion. We found the thick MTZs (>100m), imaged as the diffusive Moho, commonly accompanied by sub-Moho events.
Description:M.S. Thesis. Ph.D. Thesis. University of Hawaiʻi at Mānoa 2019
Pages/Duration:57 pages
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: M.S. - Geology and Geophysics

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