?268 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
believed, the overlying crust along with them. The strain so set up 
was believed to be relieved through rebound on the fault plane at 
the instant of the earthquake.'® This theory has been further de- 
veloped by Lawson under the name “crustal creep and elastic 
rebound ” theory.'® 
Its inadequacy.—As already ‘pointed out, the elastic rebound 
theory of earthquakes is a reversion to the notion that within any 
district an earthquake is the result of a slip on a unique plane of 
faulting, and this new theory was set up without any apparent 
attempt to fit it to other earthquakes. Evidence of vertical, as 
well as horizontal, displacement along the San Andreas rift was, 
however, to be noted, especially at Skinner’s ranch, where the writer 
among many others examined it. It is perhaps true that the revealed 
displacements upon the San Andreas rift were proportionately more 
largely horizontal than in the case of many other earthquakes; but 
lateral displacements of the same order of magnitude combined with 
large vertical displacements were measured, for example, in connec- 
tion with the Japanese earthquake of 1891 and the Owens Valley 
earthquake of 1872. One of the most striking things about earth- 
quakes is the almost monotonous uniformity observed in the nature 
of the phenomena which accompany them. 
Now that geodetic observations have been completed over a sufli- 
cient area of the southwestern United States to determine changes 
of position of triangulation stations since the locations made before 
the earthquake of 1906, it has been learned that these movements 
have been quite different from those claimed in the California report 
to have taken place. The maximum movement recorded is now found 
to be, moreover, not even within the region of the San Andreas rift. 
Thus the elastic rebound theory of earthquakes, far from explaining 
earthquakes generally, can not be made to fit the facts for the one 
earthquake to which it was originally applied.*° 
Sekiya’s wires—Many years ago Prof. S. Sekiya undertook to 
represent the sequence of directions of shock received at his earth- 
quake station during a single earthquake with the result of showing 
that so complex are these motions that to represent their directions 
18 Hf, EF, Reid, ‘‘On mass movements in Tectonic earthquakes and the depth of the 
focus,’ Gerlands Beitr. z. Geophysik, Leipzig, vol. 10, 1910, pp. 318-351; also Rept. State 
Earthq. Invest. Comm, (Carneg. Inst., Wash.), vol. 2, 1910; also ‘‘ The elastic rebound 
theory of earthquakes,” Bull. Dep. Geol., Univ. Calif., Pub., vol. 6, 1911, pp. 413-444. 
2 A, C. Lawson, ‘‘ The mobility of the coast ranges of California, an exploitation of the 
elastic rebound theory,’’ Bull. Dept. Geol., Univ. Calif. Pub., vol. 12, No. 7, 1921, pp. 
431-473, 19 text figs. 
20 William Bowie, ‘Earth movements in California,’ Spec. Pub. No. 106 (Ser. No. 
273), Dept. of Commerce (U. S. Coast and Geodetic Survey), Washington, 1924, pp. 1—22, 
figs. 1-6. Arthur L. Day, “The study of earth movements in California,” address of the 
president of the Washington Academy of Science, Jan. 138, 1925, Science, vol. 71, No. 1578, 
Mar, 27, 1925, p. 325. 
