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County has experienced very minor tremors on several occasions, but none could be rated as an earthquake. 9. Landslides. Landslides are the collapse of a mass of earth and rock down a steep slope or cliff. These often occur with other natural hazards such as earthquakes and floods. Landslides are not a serious risk in Cabarrus County due to the relatively low height of the hills in the county. Limited areas of steep slopes associated with the banks of major watercourses in the county could collapse under heavy rainfall to produce a localized landslide. The potential of damage to lives or property from this type of natural hazard is low within the county. 10. Soil Subsidence. Soil Subsidence is the sudden or gradual downward movement of the ground surface. This is a localized problem within the eastern area of the County. This area is the site of numerous abandoned sub - surface mines that date back to the gold - mining operations in Cabarrus County during the first half of the 19 Century. As the structures supporting the original mine shafts give way, these shafts collapse, occasionally causing "sink holes" to appear. As more development occurs in this area of the County, the likelihood of damage to structures from this hazard increases. However, no incidents of this type have occurred in the county between July 2004 and December 2009. 11. Drought and Extreme Summer Weather. (a) A drought is defined as a condition of abnormally dry weather within a geographic region where some rain is usually expected. This is caused by a lack of precipitation in conjunction with wind, high temperatures, and low humidity. This lack of rain in a region results in a number of problems. There are varying degrees of severity in a drought. This severity depends on the demand on water in a region, duration, and intensity. (b) There are four types of droughts: (1) Meteorological Drought — This is a reduction of precipitation over time. This definition is regionally based. In the United States, this is indicated by less then 2.5mm of rainfall in 48 hours. This is the first indication of a drought. (2) Agricultural Drought — This occurs when soil moisture cannot meet the demands of a crop. This type of drought happens after a meteorological drought but before a hydrological drought. (3) Hydrological Drought - This type refers to reduction in surface and subsurface water supplies. It is measured through stream flow and water levels in lakes, reservoirs, and groundwater. (4) Socioeconomic drought — This occurs when water shortages affect people, either in terms of water supply or economic impacts (i.e., loss of crops so price (W increases). Annex A Hazard Identification and Analysis A -8 1 December 20 Achment number 5 F -6 Page 112