Earthquake Science PDF

EARTHQUAKE Learning Objectives 1.Define fault and explain how it is formed. 2.Describe the three types of faults and relate with the types of stress 3.Describe the effects of bending of rocks along faults. 4.Illustrate how movements along faults generate earthquakes What is an Earthquake?...

EARTHQUAKE Learning Objectives 1.Define fault and explain how it is formed. 2.Describe the three types of faults and relate with the types of stress 3.Describe the effects of bending of rocks along faults. 4.Illustrate how movements along faults generate earthquakes What is an Earthquake? An earthquake is a sudden release of energy in the Earth's crust that creates seismic waves. What causes Earthquakes? Most earthquakes occur due to the movement of tectonic plates, which are large pieces of the Earth's crust that fit together like a jigsaw puzzle. Outer Layer of the earth Crust is the outermost solid portion of earth. Lithosphere region that carries entire crust, it has a segment called tectonic plates and it is elastic solid Asthenosphere, from the greek word asthenes, meaning “weak” and sphere lies beneath the lithosphere. Outer Layer of the earth Outer Layer of the earth  Pacific Ring of Fire is known for its very active tectonic plate activities, which consequently result in active earthquakes activities. Countries bordering the pacific ocean, including the philippines,Japan,China, Canada, New Zealand, North and South America, Chile, Russia, Indonesia, Mexico and Antartica, are mostly hit by destructive earthquakes that are found in an earthquake belt called the Pacific Ring of Fire.  Types of Faults Faults are fractures or cracks in the Earth's crust where movement occurs. Normal faults Reverse faults Strike-slip faults Occur when rocks move Occur when rocks are Occur when rocks slide apart due to tensional pushed together due to horizontally past each forces. compressional forces. other due to shear forces. Magnitude of Magnitude is a measure of the energy released by an an earthquake. Earthquake The Richter scale is used to measure the magnitude of an earthquake, ranging from 0 to 10 or more. Each whole number increase on the scale represents a tenfold increase in the amplitude of the seismic waves.  Seismic There are two main Seismic Waves waves are the energy waves that radiate outward from types of seismic waves an earthquake's epicenter. Primary (P) waves: Fastest waves that compress and expand rocks in the direction of wave propagation. Secondary (S) waves: Slower waves that shake the ground perpendicular to their direction of Surface travel. waves: Slowest waves that move along the Earth's surface and cause the most damage.  Seismograph A seismograph is an instrument used to record and measure the motion of the ground during an earthquake. It consists of a stationary base and a suspended weight or mass that remains stationary during an earthquake but records the motion of the ground. EFFECTS OF AN EARTHQUAKE Ground shaking: Can cause buildings, bridges, and other structures to collapse. Tsunamis: Underwater earthquakes can generate large ocean waves that travel long distances. Landslides: Slopes become unstable, leading to the downhill movement of soil and rocks.