A normal fault has strike

PHYSICS · Multi-part · Fermi University Physics · Mathematical Methods for Physics · Earth, Climate & Energy Physics · Seismology, tectonics and geodynamics

The Solid Earth, Ch The earthquake source: moment tensor, radiation and spectra

Problem

A normal fault has strike ϕf=090∘\phi_f = 090^\circ, dip δ=45∘\delta = 45^\circ and rake λr=−90∘\lambda_r = -90^\circ, with seismic moment M0=6.0×1017 N mM_0 = 6.0\times10^{17}\,\mathrm{N\,m}. Work in the frame xx north, yy east, zz down. ((a)) Find n^\hat{\mathbf{n}} and d^\hat{\mathbf{d}}, and hence write the components of the moment tensor Mij=M0(n^id^j+n^jd^i)M_{ij} = M_0(\hat n_i\hat d_j + \hat n_j\hat d_i). ((b)) Find the eigenvalues of MijM_{ij}. ((c)) State whether the P and T axes are horizontal or vertical, and give the azimuth of any horizontal axis (measured clockwise from north) and the plunge of any vertical axis.

Browse the problem library