Shock-induced anisotropy of magnetic susceptibility: impact experiment on basaltic andesite
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2007
Received: 27 August 2007
Accepted: 9 October 2007
Published: 30 October 2007
Changes in the anisotropy of the low-field magnetic susceptibility (AMS) of basaltic andesite were induced by decaying stress waves and subsequently quantified. An initial shock pressure of 5 GPa was generated in a block of the target rock through impacting with a cylindrical projectile. Following the impact, the maximum or minimum principal susceptibility axes of the target were reoriented toward the shock direction at low (0.5–3 GPa) or high (>3 GPa) estimated shock pressures, respectively. Subtraction of the initial AMS demonstrated a parallelism between the induced susceptibility axes and the shock direction. These results suggest a potential application of AMS as an indicator of the propagation directions of stress waves generated in rocks at terrestrial impact structures.