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11,4 Mitigation of Volcanic Hazards <br /> <br />Mitigation of volcanic hazards is predominantly in the areas of monitoring volcanic <br />activity, warnings and evacuation, and emergency response. That is, there are few, if <br />any, practical physical measures to mitigate the direct impacts of volcanic activity. <br /> <br />The USGS actively monitors volcanic activity in the Cascades via networks of seismic <br />sensors (which can detect earthquakes related to magma movements) as wel~ as very <br />accurate ground surface measurements, such as that which has detected the very <br />small bulge on South Sister. The USGS also has a volcanic warning system with <br />several levels of a~ert as a potential eruption becomes more likely and more imminent. <br /> <br />For the Cascades, the USGS volcano warning system (www. usgs.gov) has three <br />levels. Level One (Volcanic Unrest) means anomalous conditions that could be <br />indicative of an eventual volcanic eruption. Level Two (Volcanic Advisory) means that <br />processes are underway that have a significant likelihood of culminating in hazardous <br />volcanic activity, but when the evidence does not indicate that a life- or property- <br />threatening event is imminent. Level Three (Volcano Alert) means that monitoring or <br />evaluation indicate that precursory events have escalated to the point where a volcanic <br />event with attendant volcanologic or hydrologic hazards threatening to life and property <br />appears imminent or is underway. <br /> <br />For the Eugene/Springfield Metro Area, which is located well outside of any of the <br />direct hazard zones for any Cascades volcanic events, mitigation for volcanic activity is <br />likely a Iow priority. In the event of a minor ash flow, public warnings directing peoCe <br />(especially those with respiratory problems) to remain indoors, and minor cleanup are <br />most likely the only necessary responses for the Eugene/Springfield Metro Area. <br /> <br />~n addition, water treatment plants should be evaluated to ensure that they can handle <br />possible high turbidity events from volcanic ash falls into water supplies. <br /> <br />Emergency response plans for the Eugene/Springfield Metro Area should be updated <br />to acknowledge that major flooding along the McKenzie River is possible in some <br />volcanic eruption events. <br /> <br />The following table includes the volcanic hazards mitigation action items from the <br />master Action items table in Chapter 4. <br /> <br />Public Review Draft: October 11,2004 <br /> 11-7 <br /> <br /> <br />