Different Geological Hazards PDF 201X

Different Geological Hazards 1. Earthquakes Description/Definition: A sudden shaking of the ground caused by the release of energy along geological faults or tectonic plate boundaries. Earthquake Epicenter Definition: The point on the Earth's surface directly above where an earthquake starts. Exa...

Different Geological Hazards 1. Earthquakes Description/Definition: A sudden shaking of the ground caused by the release of energy along geological faults or tectonic plate boundaries. Earthquake Epicenter Definition: The point on the Earth's surface directly above where an earthquake starts. Example: The 1994 Northridge earthquake in California. Magnitude: 6.7; deaths: 57; direct and indirect damages: $60 billion (in 2013 dollars). 2. Landslides Description/Definition: The downward movement of rock, earth, or debris, usually under the influence of gravity. Example: A very large landslide in 2014 at Oso, Washington, which killed 43 people. The landslide covered a valley with at least 20 feet of debris. Both the government and commercial insurance companies refused to pay claims for the 2014 landslide. 3. Sinkholes Description/Definition: Sinkholes are depressions or holes that form when the surface layer collapses. Sinkholes generally occur where the subsurface layer is made of soluble bedrock (such as limestone) that can be dissolved by water. Example: A sinkhole opened in Guatemala City in 2010 and took out a leading café in that town. The sinkhole and the café together caused casualties of at least 20 people. Related Geological Hazards Landslides induced by rainfall occur when the soil becomes over-saturated and can't hold together anymore. "A landslide is generally defined as the rapid movement of earth material down a slope. This can include soil, rock, and any number of other materials that might be found on or under the surface of the earth. Such 'earthquakes' in a shaken ridge may cause some of this material to start falling off along the banks of the incline. The rainfall was so intense and so prolonged that, for some neighborhoods and hillside sections, the water just flowed down like a curtain of water from an upstairs shower." The experts warn of the danger of landslides after the heavy rains. Discuss The Different Geological Hazards Seismic hazards related to earthquakes, including ground rupture/faulting, liquefaction, strong motion, and tsunami. Landslides of all kinds, including seismically-triggered landslides, debris flows, mud flows, and rock falls. Mineral hazards such as asbestos, radon, and mercury. In addition to earthquake shaking, trigger mechanisms can include volcanic eruptions, heavy rainstorms, rapid snowmelt, rising groundwater, undercutting due to erosion or excavation, human-induced vibrations in the earth, overloading due to construction, and certain chemical phenomena in unconsolidated sediments. Analyze The Causes of The Geological hazards A landslide is a massive outward and downward movement of slope-forming materials. The term landslide is restricted to movements of rocks and soil masses. This is generally triggered by other natural hazards such as prolonged, heavy rainfall or by other source of water which increase the water content of the slope materials Causes of Landslide Landslides occur when the slope changes from a stable to an unstable condition. A change of stability can be caused by a number of factors, acting together or alone. Natural Cause of Landslide include: Groundwater (Pore water) pressure acting to destabilize the slope Loss or absence of vertical vegetative structure, soil nutrients, and soil structure. Erosion of the toe of a slope by rivers and ocean waves Earthquakes adding loads to barely stable slope