Earthshaking Science & After the Quakes

Susan Elizabeth Hough

Aside from a couple newbies, most barners know that not reading or writing reviews I manage international sales. The company is a specialty instrument company called TEGAM (www.tegam.com) One international customer uses some of our components in precision strain meters. The meter measures plate fault strain as part of Earthscope project data collection effort(www.earthscope.org). Curiosity about the project led me to these two primers on the history, science, politics and political fall out, of earthquakes. Seismology is a youthful science. Prior to the late 17th century, earthquake information was anecdotal or wrapped in mythological or misunderstood events. An early, significant attempt at a scientific understanding of earthquakes is Robert Hooke's Discourse on Earthquakes, published in 1680. In 1750, a series of minor quakes throughout the UK were widely reported at the Royal Society and in other magazines of the day. The year 1755 was a turning point. A populated, modern Lisbon, suffered an earthquake estimated at magnitude 8.5. Easy access to Lisbon allowed a wide range of scientists to study the result. The Earthscope project is one modern continuation of those early studies. Earthshaking Science provides an overview of plate tectonics and why earthquakes happen, and the difficulty that remains in precise prediction. Several models of earthquake theory are reviewed. The current state of the art involves probabilistic risk. Assessments, called regional earthquake likelihood models, consider the risk an event will happen within a certain period of time say 50% within 10 years, 80% within 50 years. Ideally, an accurate forecast that provides hours or days' notice would be useful. Seismologists are the scientific equivalent of the jack of all trades. They must understand geology, plate tectonics, physics, math... the list goes on. For the reader, detailed knowledge in these areas isn't needed. Information is 'minimally' provided to give a feel for how difficult it is to develop theories that might lead to the "holy grail" of earthquake science accurate prediction. Some, including chaos theorists, believe prediction unattainable because of the number of factors that are involved in a tremblor - many not just not understood, but also not known. After the Quakes presents us with a series of historical events, what we have learned from them, and how governments and individuals can reduce earthquake hazards. We know California has high activity. In the southern San Adreas fault (LA region) recent reports are that one side of the fault being is 7 to 9 yards behind the other, and the resulting built up stress will be released with magnitude 8.0 or higher quake. A high risk, but preparation means a lower hazard. What about "non-earthquake" regions, like New Madrid Missouri, that suffered a series of three quakes in 1811 and 1812 that were all estimated above magnitude 7 (one of which made the Mississippi River run backwards)(note to Bonnie, WATCH OUT), or Charleston South Carolina's August 1886 quake with an estimated magnitude of over 6.6. After the Quakes points out just how many areas of the US are unprepared for earthquakes, and how science can help shape policy before the next BIG ONE, like another in the New Madrid zone, or in the Northeast New York or Boston. While the risk in California might be higher, the hazard is higher in other potential earthquake locations. There are a lot of interesting sites out there with earthquake information, and starting with Earthscope, the US Geological Survey, or searching on New Madrid, Charleston Earthquake, or regional earthquake likelihood models will lead you to some interesting sites. Recommended reading for the curious, these were a couple of interesting books..