An interesting seismic event occurred near Tori Shima, Japan, on June 13, 1984, which generated an unusually large tsunami for its size. Kanamori et al. (1993) argued that it was probably caused by...

An interesting seismic event occurred near Tori Shima, Japan, on June 13, 1984,

which generated an unusually large tsunami for its size. Kanamori et al. (1993)

argued that it was probably caused by magma injection and obtained the following

components for the moment tensor: M11 = −1.8, M22 = −1.9, M33 = 3.7,

M12 = −0.38, M31 = −0.96, M32 = 0.62 (all numbers in 1017 N m). To obtain

stable results, they constrained the isotropic component to be zero.

(a) Compute M0 and MW for this event.

(b) Compute the eigenvalues σ1, σ2, and σ3 (sorted such that σ1 > σ2 > σ3) and

express M in its principal axes coordinates.

(c) Compute the parameter , the measure of the misfit with a double-couple

source. Is its value close to that expected for a pure double-couple (DC)

source or a pure compensated linear vector dipole (CLVD) source?

(d) Decompose M into MDC and MCLVD using equation (9.14) and compute the

scalar moment of each part.

(e) Devise an alternative decomposition of M into MDC and MCLVD that maximizes the CLVD part and compute the scalar seismic moment of each part.

(f) Explain your results in (a), (d), and (e) in terms of your computed parameter

in (c).