Earthquakes Focus, Epicenter, Magnitude, and Intensity PDF

1 EARTH SCIENCE Grade 8 | Second Quarter PREPARED BY: MS. JESSA MAE SERRANO EARTHQUAKES (FOCUS, EPICENTER MAGNITUDE AND INTENSITY) IN ACTIVE AND INACTIVE FAULTS LECTURE | MODULE 2 1. Focus - The focus or hypocenter of an earthquake is where the earthquake originated from, us...

1 EARTH SCIENCE Grade 8 | Second Quarter PREPARED BY: MS. JESSA MAE SERRANO EARTHQUAKES (FOCUS, EPICENTER MAGNITUDE AND INTENSITY) IN ACTIVE AND INACTIVE FAULTS LECTURE | MODULE 2 1. Focus - The focus or hypocenter of an earthquake is where the earthquake originated from, usually underground on the fault zone. 2. Epicenter - The epicenter of an earthquake is the point on the surface of Earth directly above the epicenter. 3. Fault Plane - A fault is a weak point within a tectonic plate where pressure from beneath the surface can break through and causing shaking in an earthquake 4. Waves - Earthquake waves travel through and on top of the surface of Earth causing the shaking and vibrations on the ground. Earthquake waves can travel hundreds of kilometers causing 5. Magnitude - The magnitude of an earthquake refers to how strong the energy is being released by an earthquake while the damages it created is determined by its intensity. 6. Intensity - The intensity of an earthquake at a location is a number that characterizes the severity of ground shaking at that location by considering the effects of the shaking on people, on manmade structures, and on the landscape. 7. Seismology - the study of earthquakes. 8. Seismologist – People who study earthquakes. 8. Aftershock - Aftershocks are smaller earthquakes that may occur after the main earthquake in the same area. They are caused by the area readjusting to the fault movement, and some may be the result of continuing movement along the same fault zone. 9. Foreshock - Foreshocks are smaller earthquakes occur in the same area as a larger earthquake that follows. Not all earthquakes have foreshocks or aftershocks. Sometimes a series of similar sized earthquakes, called an earthquake swarm, happens over months without being followed by a 1 4 2 5 3 TYPES OF FAULTS  8 DIP-SLIP FAULT the movement is up or down and parallel to the dip of the inclined fault surface. It has two types, the normal and reverse. They can be distinguished depending on the movement of footwall and hanging wall. a. Normal Fault b. Reversed Fault  9 STRIKE-SLIP FAULT the movement is horizontal and parallel to the strike of the fault. The fault block may laterally move to left or to the right with respect to the opposite block. OBLIQUE- SLIP FAULT has both the strike-slip and dip slip movements