Geoscience Reference
In-Depth Information
science was open to debate. What would a global seismology be a science
of?
Or, as gerland put it, “What is the earth after all?”
6
Matter
One way to answer gerland's question was bottom-up. From this perspec-
tive, the globalization of seismology would entail the multiplication of re-
gional studies on the model of Suess's monographic method. this would
be a collaborative process, recalling humboldt's vision of a “general physics
of the earth.” As one of gerland's Strasbourg collaborators explained in
1908, studies of individual earthquakes are “building stones for the con-
struction of a large edifice, the theory of the seismicity of the entire earth.
he who wants to be active in this field must follow seismic activity through
time and space, to a lesser degree as a historian, principally however as
a geographer.”
7
Such studies were in demand both to map seismic haz-
ard and to corroborate Suess's tectonic theory, which was still contested
at the turn of the twentieth century. Not all geologists accepted that the
majority of earthquakes were tectonic in origin, resulting from movement
along fractures in the earth's crust and often related to mountain building.
8
gerland, for one, took pains to point out that the tectonic explanation of
earthquakes remained very much a hypothesis—“always only theoretically
assumed, nowhere really proven.” (he could not imagine how this theory
could explain earthquakes at sea, where there were no mountains. this was
a curious opinion, since submarine extensions of mountain chains had
been suspected to exist since ancient times, and nineteenth-century coastal
soundings had already revealed submerged ridges and hollows.) evidence
for the tectonic theory would come from correlating the location and di-
rection of individual earthquakes with features of local geology. gerland
termed this approach derisively “local observation.”
9
it led, nonetheless, to
one version of a global seismology. this was the path marked out by Mon-
tessus de Ballore, the French pioneer of a worldwide “seismic geography.”
For Montessus, the problem of globalizing seismology came down to the
question: “how then to succeed in the observation of macroseisms [that is,
earthquakes], small and large, across the entire surface of the globe?”
10
Montessus initially hoped his seismic geography would generate a uni-
versal law relating seismicity to topography. the closest he came was the
hypothesis that the highest seismicity was associated with geosynclines,
the regions where uplift and folding produced the world's great mountain
chains. But he also came to appreciate the limits of any such global gener-
