48 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



been cut through it two hundred feet in width. ' ' In a little less 

 than a mile he counted no less than 345 cracks running in every 

 conceivable direction. A marked displacement of the pipe lines 

 of the Spring Vallev Water Company also indicates a slip of the 

 San Andreas fault. Prof. A. C. Lawson, of the University of 

 California, has shown that the San Francisco peninsula has at 

 least three well-marked faults. Some of these, especially the San 

 Bruno fault, traverse the Gulf of the Farallones and the northern 

 peninsula. It must not be forgotten that the earthquake wrought 

 great damage in Marin, Sonoma, Napa, Lake, Mendocino, and 

 Humboldt counties. At Santa Eosa the destruction was very groat. 



No tidal wave or disturbance in the water of any character followed 

 the earthquake. The waters of San Francisco Bay were unusually 

 calm throughout the forenoon of April 18. 



A number of valuable records have been made orr seismographs, of 

 the Omori horizontal pendulum type, of the earth waves at various 

 points. In the Weather Bureau at Washington, D. C, the record 

 obtained by Professor Marvin of an east and west motion showed 

 that the preliminary tremors lasted for six minutes befoi'e the 

 larger wave motions were recorded. At Tokyo the duration of 

 these first preliminary tremors was nine minutes and fortj'-nine 

 seconds; at Birmingham, England, about twenty-five minutes. 

 Other records have been obtained at eight or nine stations where 

 seismographs have been installed, and in due time data will be 

 ])ublished showing the probable origin and nature of the earth 

 dislocation. This, it is thought, will be a line or plane rather than 

 a definite point or centrum. From the duration of the tremors 

 the approximate arcual distance between the seismograph and 

 the origin, can be determined. 



1906. April 18; San Francisco Bay. Captain R. Peterson, German steamer 

 "I'arda, " of Kosmos line, reports: "5:05 a. m., off the Golden 

 Gate, near the middle buoy, felt a sharp earthquake lasting from 

 3 to 4 minutes, causing every one on board to think that we had 

 struck a rock or submerged wreck. Sounding S^^ fathoms and 

 afterwards 5 fathoms. While at anchor in San Francisco Bay 

 felt shocks all daj'. " 

 NoTE.--This steamer also experienced the Valparaiso earthquake of 

 August 16, 1906, at 8:10 a. m.; also after shocks, August 17 and 

 18, while lying at anchor in harbor of A^alparaiso. 



1906. April 18; Oakland, Chabot Observatory. Prof. Charles Burckhalter; 

 duplex pendulum seismograph; 5:12:51 a. m.; duration 48 seconds; 

 directions all possible; intensity VIII-IX. Pendulum of sidereal 

 clock wrecked; mean-time clock pendulum jammed behind arc; 

 clock stood at 5:14:48, but experts believe clock raced two 

 minutes. Gravity escapement. Second severe shock 8:19:20. dura- 

 tion 5 seconds; direction northeast to southwest; intensity V. 

 Fifteen additional shocks by 1 p. m., duration from 2 to 5 seconds; 

 directions east to west; intensities II to IV. Three shocks be- 



