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do~~~~~~~ ~ ~II01001001~~0~001~ o <br />CO~IMF..NTS <br />II is not unusual to receive complaints as a result of quarry blasting operations. Vibra-Tech's <br />experience indicates Ihal complaints can be attributed to one or a combination of the following: <br />I) The human body can sense velocities as low ns .03 or .04 inches per <br />second. The Degree of perceptibility, however, is na a reliable indication <br />of whether or not vibration damage is possible or likely. <br />2) Air-borne concussion and associated noise can be quite startling, <br />especially when unexpected, and concussion as well as ground vibration <br />can cause perceptible motion within buildings. Unless the concussion is <br />sufficient to produce extensive window breakage other concussion damage <br />to buildings is not possible. <br />3) Most, if not all, homes have cracks in plastered walls and ceilings. <br />Moreover, their number and length usually increase with time as a result of <br />many factors. "these factors include settlement, lutigue, swelling, and <br />shrinking of +voudcn members with moistru'e changes, and many others. <br />~'hc USBM has published a list of forty causes of cracks in masonry and <br />plastered ceilings and walls which are related to cunsttuction and design <br />practices found in many homes. Very often the homeowner is unaware of <br />Ihese factors and the defects which they create until an unusual event <br />(explosion, sonic boom, thunderstorms, etc.) draws his/her aucsdion to <br />them, whereby he/she assumes the defects which he/she discovers m'e new. <br />6 <br />