Resolution 7478 hazard mitigation

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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan Volume 2 — Hazard Inventory with various pre-existing lung diseases. Ashes with high crystalline silica content may also increase risk for suture silicosis. Technical analysis is required to determine silica component of the ash. 4.1.4.3.2. SECONDARY CONSEQUENCES: Unknown at this distance from source volcanoes. 4.1.4.4. Potential for Cascading Effects Volcanic ash is capable of various degrees of destruction, largely based on the distance it has traveled from the volcano of origin. Ash falling to the surface in areas near the volcano is much coarser and heavier than the ash that winds can carry for hundreds of thousands of miles from the eruption. Since the principle volcanic ash producing threats are located at least 800 miles west of Hennepin County, the destructive potential is restricted to the characteristics of ash that can be wind -transported that far. The most significant impacts at this distance involve the critical safety threat of aircraft flying through invisible high - altitude ash clouds. Sensitive electronic devices including computers, communications equipment, medical devices, and other critical equipment can be damaged by the abrasive and electrically charged particles. Finally, human and animal health impacts can occur because of the effect that the irritating volcanic ash has on the respiratory system and on eyes. 4.1.4.5. Geographic Scope of Hazard Blc Most volcanic ash is produced during explosive volcanic eruptions. Explosive volcanoes are found along the boundaries of Earth's converging tectonic plates that are converging, such as along the Pacific Rim, sometimes called the Ring of Fire. Other volcanic activity is at mantle plumes, called 'hot spots, which melt through tectonic plates. The closest volcano to Hennepin County is the Yellowstone Caldera, located about 800 miles west, in northwest Wyoming. The belt of volcanoes in the Cascade Range are about 1300 miles west of Hennepin County in eastern Washington State. Prevailing winds from the west set up Minnesota as a potential recipient of ash from volcanic eruptions in the western United States, Canada, and Alaska. 4.1.4.6. Chronologic Patterns Unknown, pending conclusion of the Hennepin County Emergency Management assessment in 2024. 4.1.4.7. Historical Data Bld Several major eruptions have occurred in North America where ash clouds traveled great distances. These include the Spurr Volcano, Alaska (27 June 1992); Mount Saint Helens, Washington (18 May 1980) and the Novarupta Volcano, Alaska (06 June 1912). Ash from the Spurr volcano traveled over Minnesota (see graphic at the beginning of this section) in September 1992. Pre -Historic Evidence Some extremely large volcanic eruptions occurred in the geologically recent past in the Yellowstone Super -Volcano complex in northwestern Wyoming. The United States Geological Survey estimates an average recurrence rate of explosive volcanic eruptions at Yellowstone to be between 600,000 and 800,000 years. The pervious explosive eruptions have been the Lava Creek Eruption, Yellowstone, WY (630,000 years ago); the Mesa Falls Eruption, Yellowstone, WY (1.3 million years ago); and the Huckleberry Ridge Eruption, Yellowstone, WY (2.1 million years ago). Massive ash falls were generated 30