Earthquakes and Faults | Grade 8 Science DepEd MELC Quarter 2 Module 1

[Music] hi there we're glad you made it to the second quarter in this video we are going to discuss about earthquakes and faults so let's get started did you know that the philippines is located along the ring of fire the philippines is located somewhere here this is not the actual location but this is just for representation purposes the ring of fire refers to the region around the pacific ocean that is commonly hit by earthquakes and volcanic eruptions an earthquake is one of the most horrifying phenomena that anyone can ever experience we first thought that the earth is rock solid and steady however you may have experienced that the ground shakes and this contradicts to what humans believed before earthquakes have caused destruction all over the world even in the past people have started recording these events no wonder scientists have been working very hard to find ways to predict when an earthquake occurs we cannot stop this natural event from occurring however we can learn all about earthquakes and prepare for it earthquakes are associated with faults when a fault suddenly moves an earthquake occurs a fault is a break in the earth's crust and along the break significant movement has taken place the word break refers to a crack in the ground while crust refers to the outermost layer of the earth we live on the surface of the crust and significant movement means that the rocks have been displaced or shifted considerably now let's do this activity prepare sand in a container arrange two sheets of cardboard edge to edge pour sand along the boundary of the two sheets with a ruler flatten the top of the sand and make two parallel lines now move the cardboard slowly in the direction as shown what have you noticed what is formed in the sand what happened to the line if you did the activity right you may have seen something like this a crack forms in the sand and the lines are displaced now look at this image here did you find any similarities with the activity done earlier based on the activity and the picture you can probably guess what a fault is by now a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock mass movements now how do faults produce earthquakes to answer this question let's do another activity prepare two boxes of the same size side by side prepare a paper clip with a rubber band attached to it put two holes on one box and attach the paper clip as shown put a tape between the two boxes and a toy house on top of the box with the paper clip pull the rubber band with one hand and use your other hand to stabilize the box what did you observe if you did the activity right you would have the same results in the rightmost picture the boxes represent the ground and the boundary between them represents the fault energy from inside the earth makes the ground move you simulated this by pulling on the rubber band there is no movement right away because of the friction once friction is overcome the ground suddenly moves an earthquake occurs some scientists describe this process as thick and slip at first the rocks are stuck together due to friction later the rocks suddenly slip generating an earthquake every time a fault slips the earthquakes but where does an earthquake start let's do one more activity get six empty boxes and three stones with different sizes pile the empty boxes one on top of the other in groups of three place one pile near one end of the table and the other pile at the other end using a stone strike one pile under the table observe the movement of the boxes in each pile repeat using the two other stones one at a time observe the movement of the boxes as soon as you strike the pile with a stone [Music] in this activity the stone is what we call the focus the portion of the table directly above where the stone was struck is the epicenter the table is the earth's crust the different sizes of the stone are the different magnitudes lastly how strong or how weak the wobbling was is the intensity earthquakes are vibrations or tremors produced within the earth's outer layer or crust [Music] an earthquake is tectonic it occurs when parts of the earth's crust break and the rocks together with a fault slide near each other or far away from each other this is often called faulting an earthquake could also be volcanic this is caused by the movement of magma beneath the surface of the earth the movement results in pressure changes where the rock around the magma has experienced stress at some point this stress can cause the rock to break or move tremors are often produced to signal an upcoming discharge at this vicinity or region the place where the earthquake originates is called focus the earth's surface directly above the focus is called an epicenter the seismic waves travel outward from the focus in all directions when energy is released scientists or experts in this field are called seismologists there are two major scales in which earthquakes are measured magnitude and intensity [Music] magnitude is the entire energy released by an earthquake at its focus earthquakes of larger magnitude are stronger and typically more destructive than those of smaller magnitude earthquake magnitude is measured using the richter scale the intensity of an earthquake is measured in terms of its geological effects and the general damage it brings or the intensity of shaking an earthquake's intensity becomes weaker when it is further away from the epicenter the philippine institute of volcanology and seismology or fevox for short use the following scale to describe the intensity of earthquakes in the philippines the measurements of intensity and magnitude are always corresponding to each other again when we say magnitude it is the energy released by an earthquake at a focus it is calculated from earthquakes recorded by an instrument called seismograph on the other hand intensity is the strength of an earthquake perceived and felt by people in a certain locality intensity is generally higher near the epicenter fevox has a diagram that displays the active fault in the philippines an active fault is one that has moved in the past and is suspected to move again experts adopt various techniques to find out if a fault is active or not [Music] one of these techniques is by reviewing the country's past recordings of earthquakes archaeologists periodically record disruptive events in history and earthquakes are one of these events another technique is by analyzing the oscillations in the past and today that come from faults oscillations are the repeating motion of a wave or a material earthquakes cause seismic waves that produce oscillations in materials with many different frequencies lastly there are also experts who determine fault activity by inspecting the fault and its surroundings for example a fault may meet a path and because of that the road is displaced or a fault may cast over a river and the river current is then changed some faults may slice through mountains and form cliffs this is not to say that anyone can spot an active fault alright here is an example an active fault offsets the entire sedimentary thickness on the other hand an inactive fault is confined within the lower sediments it does not cut or deform the younger strata so its activity terminated several years ago and poses no threat today the main components of a fault are default plane the hanging wall and a foot wall the fault plane is where the action is it is a flat surface that may be vertical or sloping when default plane is sloping as with normal and reverse faults the upper side is the hanging wall and the lower side is the foot wall when the fault plane is vertical there is no hanging wall or foot wall here are the three main types of faults normal faults form when the hanging wall drops down the forces that create normal faults are pulling the sides apart or extensional reverse faults form when the hanging wall moves up the forces creating reverse faults are compressional or pushing the sides together transcurrent or strike slip faults have walls that move sideways not up or down since we cannot predict when an earthquake will occur let's talk about some safety measures we need to do before during and after an earthquake happens first prepare your emergency kits an emergency kit should comprise of food supplies such as canned or processed goods water bottles a communication device such as a radio or smartphone flashlights and a first aid kit second know your emergency route ahead make sure it is safe to pass through and no chances of getting hit by falling debris next secure heavy or potentially dangerous objects that could fall on you and lastly prepare your fire extinguishing equipment in case a fire breaks out [Music] during an earthquake move away from windows glass and heavy objects extinguish any fire immediately ensure exit doors are open so you don't get stuck if you are in bed stay where you are and put a pillow over your head drop down to your knees take cover get under a sturdy table hold one of the table legs wait until the shaking stops then get out of the building as soon as possible [Music] after an earthquake grab your emergency kits never use an elevator you may be stuck inside if there will be power failures next stay away from damage buildings aftershocks may further damage the buildings which may lead to collapse in case of aftershocks follow the same safety steps of drop cover and hold lastly do not go home unless local authorities deem it safe now let's wrap things up a fault is a break in the earth's crust and along the break significant movement has taken place an earthquake is a vibration of the earth due to the rapid release of energy the place where the earthquake starts is called the focus along the fault plane the spot on the surface of the earth that is directly above the focus is called the epicenter the strength or energy of an earthquake is called the magnitude and the strength of the movement of an earthquake or how strong or weak is the shaking is called the intensity that's all for now see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

Views: 229,131

Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, Grade 8, MELC, Earthquakes, a fault-y setup, what is a fault, how do faults produce earthquakes, stick slip, where does an earthquake start, how strong is the earthquake, Pacific Ring of Fire, Types of Faults, Parts of Faults, Safety Measures during an Earthquake, What to do before during and after an earthquake, Tectonic earthquake, Volcanic earthquake, Focus, Epicenter

Id: 4Y55LUv6lN4

Length: 14min 40sec (880 seconds)

Published: Sun Nov 22 2020