Wednesday, March 23, 2011
Our very own local fault, the Raymond Fault, is located on maps available from the State Department of Conservation. Clearly the Japan Earthquake of of Sendai, March 11, 2011 at 9.0 is forcing many agencies and politicians to take another look at the risks of locating important infrastructure near known faults. I put together a small mosaic of the mapped fault areas, to see where structures are physically located on and near the fault (click to enlarge).
Beyond that, subsurface geological configurations are important determinants for the subterranean water structures and the flow of water in the environment above ground as well as through the aquifers underneath the ground. A general map & summary of our local groundwater issue is on my blog post, which shows how the aquifer is bounded on the north by the Raymond Fault. Many other characteristics of the soil and subsurface gradients are posted online at the California Geological Survey for review and analysis, particularly the National Geologic Mapping Database, available as a link on that site.
This kind of information has been analyzed to produce the Scenario Earthquake Loss Information which is publicly available. These scenarios are computer models which generate possible shaking areas based upon geological data collected by field researchers. On that page (at the bottom) there's a link showing severe loss in the Raymond Fault scenario, you can download that map here.
So if it hits we're in for a ride, potentially a severe one, as is the Huntington Library located directly on top of the fault, along with many other properties, including schools and civic buildings in several cities. This particular fault is not an active one (the most recent event probably occurring over 1,000 years ago), but its potential for an event is clearly there.
The impact of this information and the resulting scenarios is important for the planning process. With the increasing density and amount of human habitation on the globe now, the disastrous results of these big events are evident in the destruction of urbanized areas and infrastructure that didn't exist there before. The current scale of destruction of life is on par with events like the eruption of Vesuvius that buried Pompeii. The risk is far higher than it's ever been for the human population as well as the ecosystem, creating an imperative to intelligently manage our growth as we experience the results of climate change.
Posted by L Barlow at 11:55 AM