Earthquake and Volcanic Hazards PDF

Earthquake and Volcanic Hazards Ground Subsidence -​ Sinking of the ground because of Earthquake underground material movement -​ A ground shaking event caused by tectonic...

Earthquake and Volcanic Hazards Ground Subsidence -​ Sinking of the ground because of Earthquake underground material movement -​ A ground shaking event caused by tectonic -​ Earthquakes are commonly associated with plate movement or volcanic eruption subsidence. When two blocks of the earth's -​ Earthquakes can be tectonic or crust slide against each other, causing an volcanic in nature. earthquake , ground movement may occur, -​ Earthquake strength is measured raising or lowering the ground surface using a seismograph and thru various -​ Another way that earthquakes can cause scales. subsidence is by rapidly decreasing the load -​ The Richter Scale is used for bearing capacity, or strength, of loose earth measuring the magnitude. materials, or sediments, due to liquefaction. -​ Intensity is measured thru PSEi Scale Tsunami or Rossi Forrel Scale. -​ Series of waves caused commonly by an earthquake under the ocean floor. Earthquake Hazard Maps -​ Effects include flooding; coastal erosion; -​ Developed by PHIVOLCS to inform the drowning of people and damage to public on the various earthquake hazards properties. that may affect selected areas during an -​ Coastal alteration. earthquake. Landslide Earthquake Hazards -​ Down slope movement of rocks, solid and -​ Earthquake hazard is anything associated other debris commonly triggered by strong with an earthquake that may affect the shaking. normal activities of people in an earthquake -​ Effects includes erosion; burial and exposed community. (USGS) blockage of roads and rivers Ground Shaking -​ Damage to physical/material aspects of the -​ Disruptive up, down and sideways vibration community. of the ground during an earthquake -​ Land alteration -​ May cause infrastructures to collapse. Volcano Hazard -​ Severe damage to roads and bridges. -​ Volcano related phenomena that pose -​ May trigger other geological hazard events. potential threat or negative impact to life, Ground Rupture property and the environment in a given -​ Deformation on the ground that marks, the period of time. intersection of the fault with the earth’s Volcanic Eruption -​ surface. (PHIVOLCS) -​ Volcanic eruptions happen when lava and -​ Damage to infrastructure, especially gas are discharged from a volcanic vent. elevated ones. -​ common consequences of this are -​ Topographical alteration. population movements as large numbers of -​ Some areas may not be safe for human people are often forced to flee the moving occupation. lava flow. Liquefaction -​ often cause temporary food shortages and -​ Phenomenon wherein sediments, especially volcanic ash landslides called Lahar. near bodies of water, behave like liquid Lahar similar to a quicksand. quicksand.  -​ Mixture of water, pyroclastic materials and -​ Consisting of sulfur dioxide and hydrogen rock fragments flowing down a volcano or sulfide; poisonous to organisms. river valley. -​ Can cause acid rain. -​ Powerful enough to remove or carry away -​ Can cause corrosion of infrastructure. trees, boulders and logs. -​ May also cause respiratory ailments when -​ Buildings, houses and other structures can inhaled. be partially or completely buried by the Lava Flow lahar. -​ Molten rock that pours down from the Ash Fall slopes of the volcano. -​ Bits and pieces of pulverized rock, minerals -​ Different from pyroclastic flow; moves and volcanic glass generated from the slower because of increased density. volcanic eruption. -​ Can kill organisms, vegetation and may -​ Can block sunlight affecting weather damage roads, houses and other conditions. infrastructure. -​ May cause different infrastructure to collapse. -​ May cause corrosion and damage to agriculture. -​ Can have adverse health effects when inhaled. Such ailments include asthma, emphysema and other respiratory diseases. Pyroclastic Flow -​ Fast moving fluidized mass of rock fragments and gases. -​ Has a very high temperature; can burn everything in its path. -​ Can cause severe burns to humans and animals. -​ Because of its rapid downward movement, this hazard can travel great distances causing more damage. -​ Can destroy agricultural lands. Ballistic Projectile -​ Rock fragments ejected explosively during a volcanic eruption. -​ Classified into two: block and bombs -​ If the projectile is solid it is termed as a block. If it is in a partially molten state, it is considered as a bomb. -​ Impact of projectiles can cause serious damage to humans and properties. -​ Can travel great distances depending on the explosiveness of the eruption. Volcanic Gases