EARTHQUAKE SIGNATURES

Pacific Press Publishing Company · Mountain View, Cal. · May 23, 1906

FromSigns of the Times, Vol. 32, No. 20.

EARTHQUAKE SIGNATURES.

Three Seismographic Records: (a) that of the earthquake of April 19, 1892, at 2:49:2 A.M. Its duration was 58 seconds. This is a very long vibration. The scale of each is the same, we presume, as they are all records of the same seismograph. It is 1 to 7; that is, the pen of the seismograph passes over seven times more space than the vibration of the earth.

(b) The seismographic record of the earthquake of March 30, 1898, 11:45 P.M. The duration was 45 seconds, the most violent earthquake since 1868 until the recent one. The damage to buildings all told was estimated at $342,000. No lives were lost, but many persons were badly frightened. Notice the difference between the two signatures. The upper one is quite smooth in its tracing, while the second one looks like the tracing of a decrepit old man.

SEISMOGRAPHIC RECORD CHABOT OBSERVATORY Oakland

(c) The signature of the earthquake of April 18, 1906. The following is its description from the pen of Professor Burckhalter of Chabot Observatory.

"The above is a copy direct from the original from the seismograph of the Chabot Observatory, Oakland, Cal. It shows that the main motion was gyratory, but the wave-like, and the up and down motions were present also. The dashes and dots represent the up and down motion. The instrument enlarges the diagram, the real movement of the earth's surface being a little over half an inch, but not as much as six tenths of an inch. The time was 5:14:48 A.M., April 18, and the duration 28 seconds. The shock was so violent that the pen ran off the plate several times; that is, the instrument was not capable of recording so severe a shock."