HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Zhang, J. Articles by Makris, N. Search for Related Content GeoRef GeoRef Citation

Comment on "Estimates of the Ground Accelerations at Point Reyes Station during the 1906 San Francisco Earthquake" by A. Anooshehpoor, T. H. Heaton, B. Shi, and J. N. Brune

Department of Civil and Environmental Engineering
711 Davis Hall #1710
University of California
Berkeley, California 94720
makris@ce.berkeley.edu

The first 300 words of the full text of this article appear below.

The above-titled article presented response-time histories and spectra for the minimum acceleration amplitude of a full sine pulse that is needed to overturn a rigid, rectangular, free-standing block. The construction of the overturning spectra is achieved with the analytical solution of the linearized equations of motion of a rocking block which is pieced together at the instant when the rotation reverses and at the instant when the block enters the free-vibration regime.

While some segments of the methodology presented are correct the article contains several logical, algebraic, and typographical errors which are reflected in nearly every result presented. This discussion addresses systematically these errors and oversights. The same notation used in the original article is adopted herein. The noun article refers to the article under discussion by Anooshehpoor et al.; the noun comment refers to this discussion.

With reference to its Figure 3, the article investigates the rocking response of a rigid block subjected to a horizontal backwards displacement (motion from the right to the left of the page) with acceleration history

(1)

where is the phase angle when rocking initiates, with sin = g/A. In equation (1) A > 0, and for the acceleration history given by (1) the block will first experience a positive rotation, > 0, (rotate about point O₁ of Figure 3 of the article). Assuming zero vertical base acceleration the equations of motion of the rocking block are

(2)

and

(3)

Equation (2) and (3) are well known to the literature (for example, Yim et al., 1980; Spanos and Koh, 1984; Hogan, 1989; Makris and Roussos, 1998, among others). The sign of the last term that contains the horizontal ground acceleration is negative. Unfortunately, equation (3) of the article which corresponds to equation (2) of this discussion, has an incorrect . . . [Full Text of this Article]

This article has been cited by other articles:

				D. R. H. O'Connell, R. LaForge, and P. Liu Probabilistic Ground-motion Assessment of Balanced Rocks in the Mojave Desert Seismological Research Letters, November 1, 2007; 78(6): 649 - 662. [Full Text] [PDF]

				J. N. Brune, A. Anooshehpoor, B. Shi, and Y. Zeng Precarious Rock and Overturned Transformer Evidence for Ground Shaking in the Ms 7.7 Kern County Earthquake: An Analog for Disastrous Shaking from a Major Thrust Fault in the Los Angeles Basin Bulletin of the Seismological Society of America, December 1, 2004; 94(6): 1993 - 2003. [Abstract] [Full Text] [PDF]

				A. Anooshehpoor, J. N. Brune, and Y. Zeng Methodology for Obtaining Constraints on Ground Motion from Precariously Balanced Rocks Bulletin of the Seismological Society of America, February 1, 2004; 94(1): 285 - 303. [Abstract] [Full Text] [PDF]