Tomographic imaging of <i>P</i> and <i>S</i> wave velocity structure beneath northeastern Japan

• Dapeng Zhao

• Akira Hasegawa

• Shigeki Horiuchi

抄録

The seismic body wave tomography method has been improved and extended to adapt to a general velocity structure with a number of complexly shaped seismic velocity discontinuities (SVDs) and with three‐dimensional variations in the velocities in the modeling space. An efficient three dimensional ray tracing algorithm which iteratively uses the pseudobending technique and Snell's law is developed. The large and sparse system of observation equations is solved by using the LSQR algorithm. This method is applied to 18,679 arrival times from 470 shallow and intermediate‐depth earthquakes in order to study P and S wave tomographic images beneath northeastern Japan. In addition to first P and S wave arrivals, clear later arrivals of SP waves converted at the Moho and PS and SP waves converted at the upper boundary of the subducted Pacific plate (UBPP) are also used in the inversion. The UBPP, Conrad and Moho are taken as three SVDs, and their depth distributions obtained by previous studies are used. High‐resolution P and S wave tomographic images down to a depth of 200 km have been determined. Large velocity variations amounting to 6% for P wave and 10% for S wave are revealed in the crust and upper mantle. In the crust low‐velocity (low‐V) zones exist beneath active volcanoes. In the upper mantle the low‐V zones dip toward the west from the volcanic front. A high‐velocity (high‐ V) zone corresponding to the subducted Pacific plate is clearly delineated. Most earthquakes in the lower plane of the double‐planed deep seismic zone are found to occur in relatively high‐V areas. The obtained tomographic images are also found to explain other seismological observations well.

収録刊行物

• Journal of Geophysical Research: Solid Earth

  Journal of Geophysical Research: Solid Earth 97 (B13), 19909-19928, 1992-12-10

  American Geophysical Union (AGU)

キーワード

• Paleontology
• Space and Planetary Science
• Earth and Planetary Sciences (miscellaneous)
• Atmospheric Science
• Earth-Surface Processes
• Geochemistry and Petrology
• Soil Science
• Water Science and Technology
• Ecology
• Aquatic Science
• Forestry
• Oceanography
• Geophysics

詳細情報

• CRID: 1363670320746013056
• NII論文ID: 80006848690
• DOI: 10.1029/92jb00603
• ISSN: 01480227
• ISSN: http://id.crossref.org/issn/01480227
• Web Site: https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F92JB00603
• Web Site: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/92JB00603
• データソース種別:
  • Crossref
  • CiNii Articles