Geography Natural Hazards By: Annie Breier

Natural Hazards of the U.S. we will be discussing Hurricanes Earthquakes Tornadoes Volcanoes Tsunamis Winter storms Information on natural hazards can be found at USGS

Hurricanes A tropical storm with winds that reach a speed of 74 mph The eye of the storm is 20-30 miles wide and extends over 400 miles Dangers include torrential rains, high winds, and storm surges Conditions that must be present: Low-pressure system, warm temperatures over the ocean, precipitation, and tropical wind patterns over the equator

The Saffir-Simpson Hurricane Scale This scale is a 1-5 rating based on the hurricane’s intensity. It estimates the potential damage and flooding expected. Category 1 Hurricane: Winds 74-95 mph, storm surge 4-5 ft above normal. No major damage except to mobile homes and trees and some coastal flooding. Category 2 Hurricane: Winds 96-110 mph, storm surge 6-8 ft above normal. A little roof, door, and window damage. Category 3 Hurricane: Winds 111-130 mph, storm surge 9-12 ft above normal. Structural damage to residences and buildings, large trees blown down. Category 4 Hurricane: Winds 131-155 mph, storm surge 13-18 ft above normal. More extensive damage with complete roof failures, trees and shrubs all blown down, complete destruction of mobile homes Category 5 Hurricane: Winds greater than 155 mph, storm surge greater than 18 ft above normal. Complete roof failure, complete building failures, severe window and door damage

Earthquakes A trembling or shaking movement of the earth’s surface. Most earthquakes are minor tremors however larger ones begin with slight tremors, then one or more violent shocks occurs. Seismic Waves, Seismic Deformation, and Plate Tectonics all take part in the formation of earthquakes Damage and death result from falling structures and flying glass and objects.

Earthquake Magnitude – Richter Scale M=1 to 3: Recorded on seismographs, but not felt M=3 to 4: Often felt, no damage M=5: Widely felt, slight damage M=6: Damage to poorly structured buildings M=7: “Major” earthquake, causes serious damage. M=8: “Great” earthquake, great destruction, loss of life M=9: Rare great earthquake, major damage

Tornadoes Tornadoes are the most violent storms around. The wind speeds are estimated at 250 mph or more. A Tornado is a violently rotating column of air which extends from the base of the thunderstorm and then comes in contact with the ground.

Tornado Characteristics Wind: Strong and destructive. These are the fastest winds on earth which rotate up to 300 mph Rain/Hail: Tornadoes are associated with thunderstorms and flash flooding may occur Total destruction of homes: destruction usually occurs with mobile homes, business, and cars Extensive tree damage: to electric and telephone lines Utility line breaks Damaged or destroyed radio and television towers

Tornado Fujita Scale F0 and F1 tornadoes: 70% of all tornadoes that occur in the U.S. They cause minor damage F2 and F3 tornadoes: 28% of tornadoes in the U.S. They cause injuries and deaths F4 and F5 tornadoes: 2% of tornadoes in the U.S. They cause 70% of death and destruction

Volcanoes A vent in the earth’s surface which magma (molten rock), gases and ashes erupt from time to time. Five Types of Volcanoes: Composite: form impressive peaks and erupt in very explosive ways. Shield: huge and produced by hot spots Cinder Cones: a steep hill shape and the most common type in the world Spatter Cones: created when fluid hot clots falls back down and forms steep-sided accumulations Complex: made of multiple flows, ash layers, domes, or cones

Tsunamis Tsunamis are waves, created by volcanic activity and landslides and travel across the ocean having extremely long wavelengths. When it makes contact with land, the results are extensive. Erosion, inhalation of trees and coastal buildings and flooding are results of tsunamis. They are often fatal. Tsunamis are also associated with earthquakes

Winter Storms Winter Storms are known as the deceptive killers Extreme Cold: accompanies a winter storm and this can cause frostbite and hypothermia and can become life-threatening Ice Storms: heavy storms can bring down trees, electrical wires, telephone polls, and lines. Heavy Snow Storms: can paralyze a city and can collapse buildings. Heavy snow can lead to avalanches Snow: Flurries: light snow, no accumulation Showers: snow falling for brief periods, some accumulation Squalls: brief snow showers with gusty winds, significant accumulation Blowing Snow: wind-driven snow, reduces visibility and drifting Blizzard: winds over 35 mph with blowing snow

Activity Students will be separated into groups to research two natural hazards in the U.S. Students will supply definitions, occurrence, destruction, and fatalities Letters to friends/family will be written about the region of the U.S. where the natural hazards occur and displays will be made