Earthquake mechanics

405

Earthquake

Mechanics.

K. Kasahara.

Cambridge

University

Press, Cambridge,

198 1,

XIII + 248 pp., Estg. 25.00, (Hardcover).

Much of this book is based on material form to beginning

graduate

not so high as to confound

students.

which the author

That describes

all but those who are already

but high enough to provide material for the student getting to grips with the subject. The book is intended earthquake earthquake

has presented

in lecture

the level at which it is pitched, well versed in seismology,

prepared to invest time in to be an introduction to the

phenomenon, and treats all the major aspects of modern development in seismology, given the restrictions of a slim volume which cannot devote

itself to any one aspect at great depth. This is strictly a book about earthquakes. Detailed discussions of such other important branches of seismology as wave motion and earth structure will not be found in it, except as they affect studies of the earthquake source itself. The book begins with a general introduction to the properties of the earthquake source. Concepts of magnitude, energy, source volume and earth strain are presented, together with derivations of formulae where appropriate. The focal mechanism is introduced via the radiation pattern. The force representation of a source is established, and then various source configurations are examined. These are then related to the physical constraints of movement on faults, and to the modelling of dislocations in two and three dimensions. There is a natural progression then to the examination of the evidence for moving dislocations, a chapter whose clarity I found particularly appealing. The author deals first with teleseismic evidence for rupture propagation, and goes on to treat seismic moment and the source time function, then devotes a lengthy section to the synthesis of seismic effects. Most of the remainder of the book deals with the physics of the earthquake source rather all treated,

than the geometry.

together

This physics

Rock failure,

with a discussion

is then placed

friction,

dilatancy

of likely processes

in the context

of global

and strike-slip

of deep-focus

seismicity

are

earthquakes.

in a chapter

which

ranges over concepts of plate tectonics, strain and stress fields in the neighbourhood of faults, seismic gaps and anelastic crustal movements, to name a few topics. A final chapter tectonic

covers various aspects of earthquake prediction, including statistical and predictions as well as physical predictions. Some attention is also given to

the evaluation much attention

of predictions, as it merits.

a topic which perhaps

does not normally

receive as

The book is clear and well written. Typographical errors do exist, but they are rather hard to find. There is a liberal inclusion of diagrams, which are generally clear with the possible exception of some of the three-dimensional perspective drawings. I shall find it most useful.

WARWICK

D. SMITH (Wellington, New Zealand)