Modeling Surface Waves from Aboveground and Underground Explosions in Alluvium and Limestone

Abstract

The May 2012 HUMBLE REDWOOD III (HRIII) experiment series in New Mexico provides a unique dataset to study surface‐wave generation from explosions conducted above and underground for different rock types. Four 90.6 kg trinitrotoluene‐equivalent explosions were detonated either at 2 m height‐of‐burst (HOB) or 7 m depth‐of‐burial (DOB) at separate alluvium and limestone test sites. For the alluvium site, data from a temporary seismoacoustic network show that fundamental‐mode surface waves (![Graphic][1] ) from the 7 m DOB in‐alluvium shot were four to five times larger than the above‐alluvium shot. The ![Graphic][2] amplitudes from the 7 m DOB limestone shot were 15 times larger than ![Graphic][3] recorded from the collocated 2 m HOB shot. To model these differences in ![Graphic][4] , we generated 1D velocity models for both test sites using observed surface‐wave dispersion. We considered two different methods for synthetic seismogram generation. For the aboveground shots, we have coupled near‐field blast wave pressures and shapes with source medium properties to model seismic data at distance. For the underground shots, we use explosion source theory to estimate a moment for scaling explosion synthetics. For both above and underground shots, the synthetics provide excellent fits to the observed 1–5 Hz ![Graphic][5] data. This modeling provides a viable technique to predict peak particle velocities for surface and aboveground explosions in different rock types that can be used to estimate combined seismoacoustic yields. Online Material: Movies of four explosions studied in this paper. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif [3]: /embed/inline-graphic-3.gif [4]: /embed/inline-graphic-4.gif [5]: /embed/inline-graphic-5.gif