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general were in a very bad way because they had been too much influ-
enced by accidental circumstances of local intensity. It seemed desirable
to have some objective and instrumentally-founded means of comparing
earthquakes with each other.”
184
thus the original purpose of Richter's
scale was to avoid “misinterpretation” by the public of the comparative
“importance” of earthquakes; only later did the goal emerge of achieving
an “objective and instrumentally-founded” measure of relative intensity.
Finally, Richter pointed to a further use of the scale, one which he implied
was unanticipated: “even within a limited region such as California it had
advantages, and when it developed that it could be expanded to cover the
entire world, the value of the thing was greatly increased.” Read carefully,
Richter's account contradicts the prevailing understanding of the scale. It
did not originate in a quest for a universal, objective, and absolute measure
of earthquake strength. to the contrary, the initial goal was a local and rela-
tive basis for classifying earthquakes—but one that the public would not
“misinterpret.”
Specifically, the goal was a basis for comparing actual damage with the
damage to be expected based on the earthquake's intrinsic violence. It was,
in other words, a matter of comparing the “is” and “ought” of an earth-
quake.
185
the same interpretation emerges from Wood's private correspon-
dence at the time. He repeatedly searched for an adequate way to express the
gap between an earthquake's intrinsic potential for violence and its actual
effects. For instance, a shock that hit Santa Barbara in 1928 proved “too
strong here for useful registration” by seismograph, forcing him to rely on
felt reports. Yet his impression was that the damage was out of propor-
tion to the quake's strength. “the close proximity of the origin, unsuitable
building and unsuitable foundation ground—rather than great force (no-
tice that I avoid intensity)—appear to be the factors which led to so much
destruction.”
186
neither “intensity” (based on observed effects) nor “force”
(proportional to acceleration) was the word Wood was looking for. Clearly,
a new vocabulary was needed. Wood expressed a similar frustration toward
the end of his work on the revised scale. He told Byerly, “though I have
worked hard on this scale, it still contains inconsistencies such as the one
you point out respecting the chimney. I have never experienced an earth-
quake in which all works of construction were greatly damaged or destroyed,
but such earthquakes have occurred. Such a fault slip as occurred in 1906 or
in 1915 must be indicative of great
energy
whether or not productive of great
intensity.
there were anomalies in 1906 and in any experience there always
are. . . . no scale is or can be perfect, but before we adopt this one or accept
any other change we must do our best to adjust the definition and eliminate
