We may never see any degree of pin point accuracy. T he Southern California Seismic Network records more than 10,000 earthquakes in an average year. Not including aftershocks, about 100 earthquakes larger than 3.0 occur each year. G eologists can demonstrate that at least eight major earthquakes have occurred in the past 1,200 years with an average time spacing of 140 years, plus or minus 30 years. The last such event occurred in our area in 1857.
Fire hazards develop.
Most, if not all of these problems can be minimized or avoided entirely with a properly planned and executed bolting. I n the 1991, 5.8 Sierra Madre quake this logic fooled the owners of over 500 previously undamaged chimneys and moved a number of unbolted homes off foundations. I have heard that bolting can actually cause greater damages. E xperts in the physical sciences tell us that a properly anchored floor diaphragm uniformly distributes load, and actually strengthens the components, while keeping your home securely in place. The truth is that the bolts never come into action until the house starts to move.