Quarter 2 Reviewer in Science 8 (STE) PDF

QUARTER 2 REVIEWER IN SCIENCE 8 (STE) EARTHQUAKES & FAULTS What is an Earthquake? An earthquake is a vibration of the Earth due to the rapid release of energy. Shaking of the ground due to vibrations caused by the Types of Earthquakes Fault? Types of Fault Ho...

QUARTER 2 REVIEWER IN SCIENCE 8 (STE) EARTHQUAKES & FAULTS What is an Earthquake? An earthquake is a vibration of the Earth due to the rapid release of energy. Shaking of the ground due to vibrations caused by the Types of Earthquakes Fault? Types of Fault How do faults cause quakes? Energy from inside the Earth makes the ground move/movement of the molten rock in the earth’s interior. There is no movement right away because of friction.  ELASTIC REBOUND THEORY Is the sudden release of stored strain in rocks that result in the movement along a fault. Elastic Rebound Earthquakes occur when rocks slip along faults HOW TO DETERMINE IF A FAULT IS ACTIVE OR INACTIVE?  ACTIVE and INACTIVE FAULTS Earthquake faults are caused by the movement of Earth's lithospheric plate. Active faults can generate earthquakes while inactive faults can no longer produce earthquakes. DEPARTMENT OF EDUCATION  Active faults – are known to have recently generated earthquakes WITHIN the last 10, 000 years. Effects of movements on an active fault: Strong ground motion Landslide and rock falls Tectonic deformation/ground rupture  Inactive faults – do not show signs of ever having generated an earthquake IN THE LAST 10, 000 years. DEPARTMENT OF EDUCATION Focus and epicenter  FOCUS AND EPICENTER The focus or hypocenter The epicenter is a is the point within the earth location on the earth's where seismic waves surface directly above originate. It is the zone of the focus. weakness where the breaking first starts. The fault plane is the flat surface along which there is slip (fault) during an earthquake. DEPARTMENT OF EDUCATION Types of Earthquake according to Depth of Focus TYPE FOCAL DEPTH FROM EARTH’S SURFACE SHALLOW- < 70 km FOCUS INTERMEDIATE- 70 – 300 km FOCUS DEEP-FOCUS About > 300 90% of all earthquakes occur lesskm than 100 km from the surface, whereas only about 3% may be classified as deep. Shallow-focus earthquakes can cause more destruction than deep-focus earthquakes. DEPARTMENT OF EDUCATION The PHIVOLCS (Philippine Institute of Volcanology and Seismology) uses the PHIVOLCS Earthquake Intensity Scale (PEIS) Earthquake Hazards What is TSUNAMI? A sudden push from an underwater fault can produce a wave called a TSUNAMI (Harbor Waves). QUARTER II SCIENCE GRADE 8 SEISMIC WAVES AND THE LAYERS OF THE EARTH  The energy that travels under the surface layer of the earth and causes an earthquake is called seismic waves. Seismic waves carry the energy of an earthquake away from the focus. Seismic waves make it possible to study the interior of the earth. Waves can be refracted  SEISMIC WAVES A. Body waves - B. Surface Waves  Primary waves (P –  Love waves waves)  Rayleigh waves  Secondary waves (S – waves) https://thumbs.dreamstime.com/z/earthquake-scene-town-illustration-6373406 4.jpg DEPARTMENT OF EDUCATION A. BODY WAVES Body waves come spherically from the focus traveling entirely within the interior of the Earth. 1. Primary Waves (P-Waves) P-waves produce a fastest series of contractions and expansions that are in the direction of wave propagation. First to be recorded. 2. Secondary Waves (S-Waves) The speed at which the S waves travel is almost half the speed of Primary Waves. Second to be recorded. S waves are the ones to reach any location after the primary waves when an earthquake occurs.  DIFFRERENCE IN THE ARRIVAL TIME OF BODY WAVES Velocities are greater in mantle rock than in the crust. Velocities generally increase with pressure, and therefore with depth. If P wave passes through solid to liquid media, its velocity decreases.  DIFFRERENCE IN THE ARRIVAL TIME OF BODY WAVES S-waves do not pass through the outer part of the core (made of liquid iron and nickel). P-wave velocities increase dramatically at the boundary between the liquid outer core and the solid inner core. B. SURFACE WAVES Surface waves are similar in nature to water waves and travel just under the Earth’s surface. They are typically generated when the source of the earthquake is close to the Earth’s surface. Although surface waves travel more slowly than S- waves, they can be much larger in amplitude and can be the most destructive type of seismic wave. 1. Rayleigh Waves also called ground roll, travel as ripples like those on the surface of water (rolling ocean waves). People have claimed to have observed Rayleigh waves during an earthquake in open spaces, such as parking lots where the cars move up and down with the waves. 2. Love Waves cause horizontal shearing of the ground or move the ground in a side-to-side movement damaging the foundations of buildings. usually travel slightly faster than Rayleigh waves Understan ding Typhoons  TROPICAL CYCLONE is characterized by winds that go around a center where clouds appear in a spiral arrangement. It is also described as a system of thunderstorms that move around a center.  PHILIPPINES Typhoon is a system of thunderstorms that move around a center. It develops in the North-Western part of the Pacific Usually moves in a COUNTERCLOCKWISE direction. TYPHOON Western North Pacific Ocean  HURRICANE In the North Atlantic, Eastern North Pacific and South Pacific Ocean. CYCLONE In the Bay of Bengal, Arabian Sea and Western South Indian Ocean. What do we usually experience during a typhoon or “BAGYO”? Strong Winds Heavy Rain Flood Landslides Storm Surge Damage to property Loss of lives Tornadoes STORM SURGE is an abnormal rise of sea water due to tropical cyclone that occurs along the coast.  Philippine Area of Responsibility The PAR is the designated area that falls under the monitoring of jurisdiction of PAGASA.  Intertropical Convergence Zone Most tropical cyclones or typhoons occur in the area where the Northeasterly and Southeasterly trade winds converge. This area is called the ITCZ or Intertropical Convergence Zone, circulating near the equator. It is known for its lowest surface pressure, where the converging air ascends (causing low-pressure), condenses, and strengthens into sufficiently strong Tropical disturbances.  Low Pressure Area In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. The term Low Pressure Area or LPA becomes a signal for meteorologists that a typhoon is brewing on the ocean. 12/02/2024 Add a footer 57 Tropical  Tropical Cyclogenesis (Life history of a cyclone) 12/02/2024 Add a footer 59  Tropical Cyclogenesis (Life history of a cyclone) 12/02/2024 Add a footer 60 Philippine Atmospheric Geophysical and Astronomical Services Administration  CLASSIFICATION OF TROPICAL CYCLONES The classification of tropical cyclones according to the strength of the associated winds as adopted by PAGASA as of MARCH 23, 2022 are as follows: Maximum Wind Speed Category kilometers per hour (kph) Maximum sustained wind of Tropical Depression (TD) up to 62 kph Tropical Storm (TS) 63-88 kph Severe Tropical Storm (STS) 89-117 kph Typhoon (TY) 118 – 184 kph Super Typhoon (STY) Greater than 185 kph  Why is the Philippines prone to typhoons? Our country is situated near the equator where there is warm ocean water. Our country is surrounded by vast bodies of water which could supply the water vapor needed for a tropical cyclone to form. AIR IN THE SURROUNDINGS MOVES TOWARDS THE EYE DURING THE FORMATION OF TYPHOON….. Typhoons have lower air pressure in the middle thus, pulling the air towards it.  FACTS ABOUT THE TRACKING THE TYPHOON It only involves many weather instruments to predict its strength and movement. It predicts the path as to where typhoon will take its course. It involves determining the position and strength of high-and-low pressure areas. It involves predicting the movements of typhoon within 5 to 7 days, and in 6 to 12 hours whenever there is a storm. Tropical cyclones weaken/dissipate when they….. die out over land because they need warm water to sustain them. need water vapor to keep them going. Even when the tropical cyclone is still in a body of water, it may weaken and die out if the Importance of landforms Landforms such as Sierra Madre serve as an obstacle for travelling air masses making typhoon weaker.  Public Storm Warning Signals PSWS are raised to warn the public of incoming weather disturbances. Once a Storm Signal is raised, conditions are not yet necessarily felt in the given area. SOME IMPORTANCE OF TRACKING THE PATHWAY OF TYPHOON People will know how strong or weak a typhoon is. People may know the accurate time and date of the arrival of a typhoon. Residents in the affected area will be prepared for the coming of typhoon. OTHER MEMBERS OF THE SOLAR SYSTEM  Comets Composed mostly of ice, metal, and dust that grow tails when they approach the sun They are also often called as Dirty Snowballs Comets have stretched or COMETS As they approach the sun they MELT and develop a TAIL made of the escaping dust and gas. As Comets get closer to the sun the tail gets BIGGER. COMETS The tail of the comet always points AWAY FROM THE SUN because of the SOLAR WIND coming from the sun.  Kuiper Belt It is disc-shaped region of icy objects beyond the orbit of Neptune -- billions of kilometers from our sun Short-period comets come from here (less than 200 years) Oort Cloud It is filled with icy objects composed of ammonia, water and methane. Long-period comets come from here It takes 200 to hundred millions of years to complete their orbit around the sun Asteroids Asteroids are also called minor planets or planetoids. Originate from the Main Asteroid Belt between Mars and Jupiter METEOROID  Is Believe to be a fragment of an asteroid or remnant of a comet. is a piece of stony or metallic object, which travels in space. travels around the sun in a variety of orbits and at various speeds.. METEOR is a light phenomenon or a streak of light that occurs when a meteoroid burns up when it enters the Earth’s atmosphere. Also known as shooting stars.  meteors that appear glow brighter than planets or moons are called fireballs.  when fireballs explode, they are called bolides. METEORITE If the meteor does not burn up completely, the remaining portion falls to earth or a meteor that hits the earth’s surface is called a meteorite.