Appendix I

Sieh and Jahns (1984) forecasted that the next moderate Parkfield earthquake might trigger a major earthquake along a fault segment greater than 30 km long southeast of Cholame. Their forecast assumed (1) the slip was 3–4 m in 1857 and characteristic of the segment; (2) a slip rate of 3.4 cm/yr; and (3) full strain release in earthquakes.

Site-specific probabilistic seismic hazard assessments (PSHAs) and associated seismic design bases are critically dependent upon the local geological and geotechnical model. For reactor and critical non-reactor facilities on soil or softrock sites exhibiting strain-dependent behavior, estimates of site response can change significantly as site measurements and inferred structure evolve.

In many cases the ground motions developed near the surface of a soil deposit during an earthquake may be attributed primarily to the upward propagation of shear waves from an underlying rock formation. If the ground surface, the rock surface, or the boundaries between different soil layers are inclined, analyses of the response of the soil deposit can be made only by techniques such as the finite-element method.

It is well known that the most widely used earthquake magnitude scales, ML (local magnitude), M, (surface wave magnitude), and mb (body wave magnitude), are, in principle, unbounded from above. It is equally well known that, in fact, they are so bounded, and the reasons for this are understood in terms of the operation of finite bandwidth instrumentation on the magnitude-dependent frequency characteristics of the elastic radiation excited by earthquake sources.