español It would seem that Patrick Milligan of the San Bernardino Regional Water Resources Authority seems inclined to substitute sarcasm for science in his rebuttal of my public comment about the well-documented correlation between subsidence and removal of large quantities of groundwater. I am not a geologist, neither is Mr. Milligan: he is an attorney at law, while I have my Master of Arts degree in Political Science from the University of California at Riverside (1983), Bachelors of Science degree in Computer Science (1986) and Bachelor of Arts degree in Economics (1991) from California State University, San Bernardino, as well as an Associate of Arts degree in Engineering (1977) from San Bernardino Valley College. One thing that people with advanced degrees, such as Mr. Milligan and myself, are supposed to know is what they don’t know, and therefore when they need to consult with other specialists: the Neighbourhood Action and Preservation Association has consistently done this: Mr. Milligan claims to have done this also. Here’s a simple test of our competing claims:
My primary sources are:
Lofgren, Ben E, Estimated Subsidence in the Chino-Riverside and Bunker Hill-Yucaipa Areas in Southern California for a Postulated Water-Level Lowering, 1965-2015. United States Department of the Interior, Geological Survey, Water Resources Division, in cooperation with the California Department of Water Resources, 1971.
Galloway, Devin, Jones, David R., and Ingebritsen, S.E., Land Subsidence in the United States. Washington, DC: United States Geological Survey, Circular 1182, 2001.
Clarke, Tom, Water thrown on earthquake prediction: Los Angeles’ ups and downs confuse earthquake scientists. Nature, 23 August 2001.
Ball, Philip, Ground swell sensed from space: Satellites spot aquifers filling and emptying. Nature, 26 June 2001.
All of these sources indicate that removal of large quantities of ground water have caused, and will cause, subsidence in Southern California: now it’s Mr. Milligan’s turn to produces the scientists and studies that indicate that removal of large quantities of ground water have lessened the risk of liquefaction during earthquakes. Did it work in the Northridge earthquake? Did it work in the Loma Prieta earthquake of the San Francisco Bay Area? Did it work in the great Mexico City earthquake? All of these areas had substantial amounts of ground water removed prior to the earthquakes; all of them have experienced subsidence; all of them have experienced liquefaction. Subsidence risk and liquefaction risk, it would seem, go hand-in-hand, arising from the same soil types. Subsidence is preventable, with conservation and replenishment of subsoil fluids. Is liquefaction preventable, with removal of these same fluids? Mr. Milligan seems to think so. Do geologists, civil engineers, and hydrologists agree with him? If so, Mr. Milligan needs to disclose his sources to the San Bernardino Regional Water Resources Authority and to the public, as I just have mine.
Matthew K. Owen, consulting researcher, Neighbourhood Action and Preservation Association.