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the rest of his life to understanding California's seismic threat. Most im-
mediately, he conceived the ambition of surveying all of California's past
earthquakes, from the eighteenth century to the San Francisco megaseism.
this was to be no mere catalog in the style of trask or Holden. It was to be a
“synthetic study of recorded shocks”—a work of analysis, not mere compi-
lation. Wood would correlate each event with a known fault. For such a vast
job of data analysis, his goal sounded remarkably modest: “merely to bring
out clearly the suggestion that there is a causal association of earthquakes
with fault zones in this region—a relationship fraught with significance for
human affairs.”
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Wood's “synthetic study” would occupy him for nearly a
decade and make him the American scientist best versed in the subtleties of
exploiting felt reports.
Wood soon began to hone an argument for the value of noninstrumental
observations and for the integration of geophysical, geological, and social
analysis. Like his nineteenth-century predecessors, Wood viewed macroseis-
mology as a hermeneutic challenge. He devoted twenty pages to a criti-
cal discussion of his sources, including the errors arising from incomplete
records and from the exercise of his own judgment in interpreting them.
Based on this experience, in 1911 Wood drew up a set of instructions to
earthquake observers for the first volume of the SSA's
Bulletin.
the problem
with seismographic observatories, he noted, was that their goal was “the in-
crease of scientific knowledge,” rather than what “the practical public deems
of greatest importance.” More to the point, such observatories, “even if es-
tablished in fair abundance, will not afford any detailed or precise knowl-
edge of the size and shape of the area in which the shock is 'felt,' nor of the
way in which its intensity varies over this area, nor of the character of the
manifold attendant phenomena,—such as damage to structures or distur-
bances in the soil and rock.” the public urgently needed to know “when and
where will strong shocks occur in the future, and what conditions, which are
subject to human control, tend to mitigate their disastrous consequences.”
Wood's most important insight in 1911 was that this question could only
be answered by combining knowledge of geology, the built environment,
and human perceptions. Seismologists would have to study “the relations
between the places of origin and the distribution of the perceptible effects
of shocks; the relation between these effects and the geological character
of the ground where they occur; how the character of structures affects the
degree of the disaster,—in short, the interrelationships of all these things,
place of origin, phenomena, character of ground and of structures through-
out the whole area in which the shock is felt perceptibly.” Finally, true to
seismology's nineteenth-century european tradition, Wood insisted that
