Strong motion earthquake accelerograms, digitized and plotted data, Volume I - uncorrected accelerograms; Part C - Accelerograms IC041 through IC055

Abstract

The first set of 20 uncorrected digitized earthquake accelerograms was published in July, 1969 as Volume I, Part A of the present series. That volume also contained introductory material and background information describing the methods used, accuracies, etc. which should be referred to by all users of the data. Parts A and B have contained accelerograms from earthquakes dating from March 10, 1933, and are a portion of a complete series planned in 1969 covering all the important accelerograms to that time. The San Fernando Earthquake, however, provided more than twice as many records as previously available. In view of the importance of this earthquake, it was felt that we should interrupt the original plan and issue this and succeeding Parts containing San Fernando Earthquake accelerograms, before returning to the original series. The record from Pacoima Dam has received a great deal of attention. Included here are 42 seconds containing the main shock and the first clearly identifiable aftershock, together with six further aftershocks. Because of its importance and the high trace amplitudes involved, the Pacoima record was digitized from the original paper film. All the remaining paper film records were digitized from contactnegatives. Although most reproductions of the Pacoima record indicate some dim portions of the trace, the original trace was clearly distinguishable with no ambiguity. The special problems of this particular accelerogram are treated in the paper by Trifunac and Hudson listed in the references on page 5. The six portions of the Pacoima record containing the aftershocks have the following starting times, measured in seconds after the start of the main shock trace: 52. 6, 69. 6, 104. 6, 162. 0, 230. 1, and 309. 1 sec. These starting times are indicated by arrows on the reproduction of the Pacoima record appearing on page 6. Records from-buildings or arrays containing more than one instrument are included together in one. Part where possible. Part C contains records from Holiday Inn at 8244 Orion Blvd., L. A. , the Kajima Building at 250 E. First St., L. A. , (three records each) and the Union Bank at 445 Figueroa St., L. A. (two records.). As in previous reports the printout and plots contain asterisks and arrows, respectively, .indicating where the record was shifted in the digitizer when required. We should like to express our gratitude to personnel from the Jet Propulsion Laboratory who have assisted so capably on the digitizing: Miriam Blount, Jeannyne Gunkel, Jo Jean Kos, Carolyn Level and Florence Sims. In. addition we should like to thank our regular digitizers and assistants, students and otherwise, for their conscientious. work: N. R. Bacheliri, D. A. Blount, Esther Dizack, R. C. Dullien, H. H. Kwai, H. H. Law, V. W: Lee, M. Y. -C. Ngan, W. J. Raymond and K. K. Tung. We would also like to acknowledge the general support off the Earthquake Research Affiliates. The whole program has at all stages been conducted through the generous help of grants from the National Science Foundation, and- we have enjoyed the close cooperation of the staff of the Seismological Field Survey of the National Oceanic and Atmospheric Administration.

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