Additional information for “TREMOR: A Wireless, MEMS Accelerograph for Dense Arrays” (Evans et al., 2003)

ON-LINE VERSIONS This report is available via anonymous ftp on the computer " clover.wr.usgs.gov " as file " /ftp/pub/ehz/jrevans/OFR_03_159/OFR_03_159.pdf ". Use your e-mail address as the login password for username " anonymous ". Because the file is in Adobe™ Acrobat™, use only a binary transfer. Should the particular computer and path change in the future, the Acrobat™ file is also available at the USGS Web site " http://pubs.usgs.gov/products/books/openfile/ " by browser retrieval techniques. Look for " 2003 " under " Open-File Reports " or search for this volume number, " 03-159 ". 3 INTRODUCTION The length of Evans et al. (2003) necessitated transfer of several less germane sections to this alternate forum to meet that venue's needs. These sections include a description of the development of Figure 1, the plot of spatial variability so critical to the argument for dense arrays of strong-motion instruments; the description of the rapid, integer, computational method for PGV used in the TREMOR instrument (the Oakland instrument, the commercial prototype, and the commercial instrument); siting methods and strategies used for Class B TREMOR instruments and those that can be used for Class C instruments to preserve the cost advantages of such systems; and some general discussion of MEMS accelerometers, including a comparative Table with representative examples of Class A, B and C MEMS devices. (" MEMS " means " Micro-ElectroMechanical " Systems— " micromachined " sensors, generally of silicon. Classes A, B, and C are defined in Table 1.)