Geological Hazards PDF

GEOLOGIC HAZARDS - ARE NATURALLY OCCURRING GEOLOGIC PROCESSES THAT CAN CAUSE IMMENSE DAMAGE TO PROPERTIES AND LOSS OF LIVES. Earthquakes Volcanic eruption Landslides EARTHQUAKES - A sudden movement of the earth’s surface that results from...

GEOLOGIC HAZARDS - ARE NATURALLY OCCURRING GEOLOGIC PROCESSES THAT CAN CAUSE IMMENSE DAMAGE TO PROPERTIES AND LOSS OF LIVES. Earthquakes Volcanic eruption Landslides EARTHQUAKES - A sudden movement of the earth’s surface that results from the release of accumulated strain from tectonic and volcanic activities. Earthquakes can cause damage to structures. PARTS OF AN EARTHQUAKE PARTS OF AN EARTHQUAKE Fault - Are planes of fracture in rock bodies, where displacement is observable. PARTS OF AN EARTHQUAKE Hypocenter (focus) - Refers to the actual location of the seismic wave that causes the earthquake and is usually located within the earth. Seismic wave - waves responsible for the earthquake/movement of the crust. PARTS OF AN EARTHQUAKE Epicenter - is the point on earth’s surface directly above the hypocenter (focus). EFFECTS OF EARTHQUAKE  EFFECTS OF EARTHQUAKE Ground shaking - Ground shaking is the vibration of the ground during the earthquake. - May cause partial or total collapse of buildings and structures.  EFFECTS OF EARTHQUAKE Ground shaking - Frequency is the number of times a movement such as ground shaking is repeated within a certain amount of time.  EFFECTS OF EARTHQUAKE Ground displacement or surface rupture - The horizontal or vertical displacement of the ground surface along the fault zone. - Severely damages buildings and structures located adjacent to the faults.  EFFECTS OF EARTHQUAKE Ground displacement or surface rupture  EFFECTS OF EARTHQUAKE Ground displacement or surface rupture  EFFECTS OF EARTHQUAKE Ground displacement or surface rupture  EFFECTS OF EARTHQUAKE Ground displacement or surface rupture  EFFECTS OF EARTHQUAKE Liquefaction - Transformation of solid rocks and soil to a liquid-like state during ground shaking. - When it occurs, large rigid structures or objects may tilt or sink into the liquefied deposit.  EFFECTS OF EARTHQUAKE Liquefaction - Transformation of solid rocks and soil to a liquid-like state during ground shaking. - When it occurs, large rigid structures or objects may tilt or sink into the liquefied deposit.  EFFECTS OF EARTHQUAKE Liquefaction - Transformation of solid rocks and soil to a liquid-like state during ground shaking. - When it occurs, large rigid structures or objects may tilt or sink into the liquefied deposit.  EFFECTS OF EARTHQUAKE Liquefaction - Transformation of solid rocks and soil to a liquid-like state during ground shaking. - When it occurs, large rigid structures or objects may tilt or sink into the liquefied deposit.  EFFECTS OF EARTHQUAKE: INDIRECT Tsunami - Set of long, high ocean waves caused by an earthquake or disturbance under the sea. - Causes flooding and destruction of structures.  EFFECTS OF EARTHQUAKE: INDIRECT Tsunami - Set of long, high ocean waves caused by an earthquake or disturbance under the sea. - Causes flooding and destruction of structures.  EFFECTS OF EARTHQUAKE: INDIRECT Fire and Explosions - Caused by rupture of gas and electric lines during ground shaking and displacement. - Poses threat of explosions which may cause death and destruction of property.  EFFECTS OF EARTHQUAKE: INDIRECT Fire and Explosions - Caused by rupture of gas and electric lines during ground shaking and displacement. - Poses threat of explosions which may cause death and destruction of property. SPECIFICATIONS OF AN EARTHQUAKE INTENSITY AND MAGNITUDE Magnitude - Is the amount of energy released by the earthquake. It is determined by a seismograph, an instrument used to detect and measure the “size” of the seismic waves. Modern seismograph INTENSITY AND MAGNITUDE Magnitude - Is the amount of energy released by the earthquake. It is determined by a seismograph, an instrument used to detect and measure othe “size” of the seismic waves.  THE RICHTER SCALE The RICHTER SCALE is used to rate the magnitude of an earthquake, that is the amount of energy released during an earthquake. INTENSITY AND MAGNITUDE Intensity - is the measure of the ground shaking based on damage to properties. Each intensity scale is based on the geography and geological considerations of each country. The intensity scale of the Philippines : PHIVOLCS EARTHQUAKE INTENSITY SCALE (PEIS) was developed in response to the 1990 Luzon earthquake PHILIPPINE INSTITUTE OF VOLCANOLOGY AND SEISMOLOGY (PHIVOLCS) Perceptible to people only under favorable circumstances. Felt by few individuals at rest indoors. Felt by many people indoors specially in upper floors of buildings. Felt generally by people indoors and some people outdoors. Strong shaking and rocking are felt throughout the building. Some people loose their balance. People find it difficult to stand in upper floors and some people run outdoors, People find it difficult to stand even outdoors. People are forcibly thrown to the ground. Practically all man-made structures are destroyed. EARTHQUAKES: PHILIPPINES The great luzon earthquake of 1990. On july 16, 1990, a magnitude 7.8 earthquake struck the island of luzon, claimed the lives of approximately 2,412 people, with thousands more injured. This has been considered to be one of the most powerful earthquakes to hit the philippines in the 20th century. VOLCANIC HAZARDS EVENTS ASSOCIATED WITH VOLCANIC ACTIVITY THAT MAY CAUSE ADVERSE EFFECTS ON ORGANISM AND THEIR ENVIRONMENT VOLCANIC ERUPTION The discharge of materials and gas from the interior of the volcano to the surface and to the atmosphere. Triggered by addition of magma in the magma chambers and buildup of interior pressure. VOLCANIC HAZARDS  VOLCANIC HAZARDS Lava Flows - Lava is a molten rock or magma that has reached the surface of the earth. Lava flow occurs when magma contacts the surface of a volcano and erupts or overflows downhill from different volcanic openings.  VOLCANIC HAZARDS Lava Flows - Lava is a molten rock or magma that has reached the surface of the earth. Lava flow occurs when magma contacts the surface of a volcano and erupts or overflows downhill from different volcanic openings.  VOLCANIC HAZARDS Pyroclastic flows - A mass of hot, dry pyroclastic material (mixture of ash and dust and hot gases), also called tephra. - Volcanic gases carries toxic elements that can cause death to living organisms.  VOLCANIC HAZARDS Pyroclastic flows  VOLCANIC HAZARDS Tephra falls - Rock fragments and lava blobs ejected to the air by an erupting acid rain volcano. - Damage structures, break power lines, kill vegetation, and cause respiratory damage.  VOLCANIC HAZARDS Tephra falls - Rock fragments and lava blobs ejected to the air by an erupting volcano. - Damage structures, break power lines, kill vegetation, and cause respiratory damage.  VOLCANIC HAZARDS Lahar - A mixture of volcanic debris and water that flows at the slopes of the volcano or with bodies of water. - It destroys infrastructures, buries town and crops, and fills river channels.  VOLCANIC HAZARDS Lahar - A mixture of volcanic debris and water that flows at the slopes of the volcano or with bodies of water. - It destroys infrastructures, buries town and crops, and fills river channels. VOLCANIC ERUPTIONS: PHILIPPINES In 1991, mt pinatubo in the northern philippines erupted killing about 800 people. This eruption is one of the biggest eruptions in the world in the twentieth century. Mt mayon is the most active volcano in the country. Its eruption in 1814 killed more than 1,200 people and buried a town in albay. LANDSLIDES EVENTS ASSOCIATED WITH LANDSLIDE ACTIVITY THAT MAY CAUSE ADVERSE EFFECTS ON ORGANISM AND THEIR ENVIRONMENT LANDSLIDE Alsocalled landslip, occurs when earth materials (rocks, debris, and soil) move downwards along a slope. It may be caused by earthquakes or heavy rainfall or by human activities such as deforestation, blasting, and construction. FORMS OF LANDSLIDES  LANDSLIDES FORMS Earthflow - The downward flow of fine- grained materials, such as clay, fine sand, and slit.  LANDSLIDES FORMS Earthflow - The downward flow of fine- grained materials, such as clay, fine sand, and slit.  FORMS OF LANDSLIDES Mudflows - A fast moving wet flows. It is synonymous to lahars but it is a mixture of water and earth debris materials act as a viscous fluid flowing downhill.  FORMS OF LANDSLIDES Mudflows - A fast moving wet flows. It is synonymous to lahars but it is a mixture of water and earth debris materials act as a viscous fluid flowing downhill.  LANDSLIDES Rockfall - The movement of unconsolidated rock/material downslope caused by gravity.  LANDSLIDES: PHILIPPINES In the philippines, two of the most catastrophic landslides took place in leyte. 2006 guinsaugon, southern leyte landslide, where more than 1,000 people were killed. In 2003 southern leyte landslide, 200 people were killed in a landslide in southern leyte. Both events were triggered by heavy rainfall.