Two Sources of Nonisotropic Radiation From Underground Explosions in Granite

Journal Article · 23 October 2017 · Journal of Geophysical Research. Solid Earth

DOI: https://doi.org/10.1002/2017JB014718 · OSTI ID:1411684

Vorobiev, O. Yu. ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Abstract Significant tangential ground motion observed during underground explosions makes it difficult to distinguish them from natural earthquakes. Such motion can be generated by the source geometry and emplacement conditions, by the heterogeneous nature of the rock mass (mechanical properties may vary in space due to the presence of cracks, joints, faults, and various geologic layers) and also by the nonuniform in situ stress state. The last mechanism is increasingly important with depth when the difference in main principal stresses becomes significant. This paper is focused on the role of material strength of the rock mass in generation of nonradial motion during explosions in prestressed media. Numerical modeling of underground chemical explosions in granite at various depths has been conducted to compare two possible mechanisms of shear wave generation. The first, caused by rock mass anisotropy, is important at shallow depth. The second is related to elastic‐plastic relaxation around the cavity created by the explosion. Tangential motions for these two mechanisms have different signatures.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344; W-7405-southern-48
• OSTI ID: 1411684
• Alternate ID(s): OSTI ID: 1408788
• Report Number(s): LLNL-JRNL-733561; TRN: US1800272
• Journal Information: Journal of Geophysical Research. Solid Earth, Vol. 122, Issue 11; ISSN 2169-9313
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English