Boundary Type that Creates Mountains

Continent-Continent Convergent Boundary

Boundary type that creates rift valleys

Continent-Continent Divergent Boundary

Boundary Type that Creates Trenches and Volcanic Island Arcs

Continent-Ocean Convergent Boundary

Plate Boundaries, Volcanoes, Natural Disasters

What is an earthquake? Would you be surprised to learn that several million earthquakes happen every year? Seriously. Most are so small in magnitude or size that we cannot even feel them. In fact, only 20 earthquakes are efficiently reported each year in the United States Geological Survey. Wow! That is a huge difference! The Earth has four major layers. Inner core, outer core, mantle, and crust. Think of the crust and top of the mantle like the skin of the earth. This skin is made up of different pieces of rock called tectonic plates. There are about 15 major slabs that join together, kind of like a puzzle. The edges around the tectonic plates are called plate boundaries. These massive pieces of rock slide back and forth under the Earth's surface, bumping up against each other and creating a lot of tension. This tension and movement create faults, which are basically huge cracks in the rock. When the faults get stuck, they build up pressure. And when they get unstuck, you guessed it, an earthquake. So basically, an earthquake is caused by the shifting and sliding of tectonic plates on the Earth's upper mantle and crust. There are three ways that tectonic plates shift or slide. They are subduction, lateral sliding, and spreading. Subduction happens when plates crash into each other. This can cause one plate to slide under another and be destroyed. Or the edges of the plate may rise up and form mountains. Lateral sliding means that the plates slide alongside each other, which can create lots of friction. And like you might have guessed, spreading happens when plates move apart from each other. When they do, melted rock between the plates rises and cools, forming new crust. Here's an interesting fact. Nearly 90% of all earthquakes begin in the Pacific Ocean, in an area called the Ring of Fire. It's called the Ring of Fire because along with earthquakes, it's filled with many active volcanoes. More than 450! Earthquakes can be powerful enough to change the surface of the earth and can do a lot of damage. And sometimes earthquakes can even cause other natural disasters, like avalanches, landslides, and tsunamis. Pretty wild, right? The epicenter is the location of an earthquake on the Earth's surface. The closer you are to the epicenter, the more of the earthquake you will feel. Earthquakes lose intensity as they travel away from the epicenter. Scientists measure the intensity of an earthquake using a special device called a seismograph. Seismometers detect and measure the vibrations given off by an earthquake. Magnitude is the number given to record the size of an earthquake. For example, a magnitude 5.5 is considered moderate. Above 8.0 is considered a major earthquake and we see one every year or two. Earthquakes measured at 2.5 or less are usually not felt, but can be recorded. And believe it or not, there are millions that happen each year. You can make a model of a seismograph at home, and we are going to show you how. It's activity time! You can print off directions for this one on our website at learnbright.org. You'll need a cardboard box, string, a plastic cup, a marker, small heavy objects, a long strip of paper, and a friend because this is an activity for at least two people. Now comes the fun part. One friend shakes the box, alternating between hard and soft and slow and fast, while the other friend is pulling the strip of paper through the bottom. Watch the marker as it records the movement. This is exactly what a seismograph does during an earthquake. So, in a way, we have not only created our own seismograph, but our own earthquake as well. Now, we can analyze the data just like scientists. Can you tell how hard the box was shaking based on the line? Can you tell when it was barely shaking at all? You are on your way to becoming a seismologist. A seismologist is a person that studies earthquakes. It's pretty cool to watch the process, but it's even more exciting to do it yourself. You can head on over to our website to get detailed instructions for this activity. Just download the lesson plan and as always have fun! Hope you had fun learning with us! Visit us at learnbright.org for thousands of Hope you had fun learning with us! Visit us at learnbright.org for thousands of free resources and turnkey solutions for teachers and homeschoolers.

Help me make a 15 question multiple choice quiz for 8th graders about plate tectonics and continental drift. Each question should have 4 answer choices. I would like one 2 paragraph reading about evidence for the theory of plate tectonics with 2 text dependent multiple choice questions. The question topics should include how oceanic plates are made of basalt while continental plates are made of granite, what convection currents are and how they occur in the mantle, 3 questions about alfred wegener's evidence for continental drift, a question about seafloor spreading, the three types of plate boundaries, how plates are within the lithosphere, subduction zones, how locations of volcanoes, earthquakes and high elevation show where plate boundaries are.

Volcanic Eruptions Earthquakes are sometimes used in predicting volcanic eruptions. An earthquake alerts the authorities to observe a nearby volcano. When a volcano shows signs of eruption, evacuation of the nearby villages should be immediately implemented Active volcanoes are the ones that are usually closely monitored by volcanologists These are commonly located along plate boundaries specifically along the Pacific Ring of Fire. The Philippines is one of the countries that have a lot of volcanoes. The Pacific Ring of Fire is a region in the Pacific where most active volcanoes are located. The dots in the figure represent the active volcanoes in the world. Active volcanoes are those that have a recorded volcanic eruption in their history. There are two types of volcanic eruptions depending on the magma composition: the explosive type and the Hawaiian or nonexplosive type. The types of eruptions depend on the viscosity and amount of dissolved gases in a magma. Explosive eruptions have magma that is highly viscous and contains large amounts of dissolved gases. On the other hand, the Hawaiian type or nonexplosive eruptions have magma that has low viscosity and low amount of dissolved gases. Viscosity determines the ability of magma to flow. The lower the viscosity, the easier it is for the magma to flow. This viscosity of the magma is affected by silica content and temperature. Low-temperature magma with high silica content are highly viscous, high-temperature magma with low silica content has low viscosity. Therefore, in explosive eruptions, the magma could not easily get out of the vent. This impedes the remaining magma below, causing an increase of pressure. Once the pressure is released. an explosive eruption occurs. Volcanic Hazards Explosive volcanic eruptions release pyroclastic flows and materials that are considered to pose the greatest threat. The pyroclastic flows often render people in a shock state since they become overwhelmed with what they are seeing Too much pyroclastic material (eg., tephra), may bury people and severely damage the agricultural land and livestock. Damaged agricultural land could lead to famine. After an eruption, pyroclastic materials that have settled along the slope of the volcano get mixed with rainwater. This would start a mudflow or lahar moving at high speed, destroying everything along its path. Poisonous gases are also released by volcanoes. These gases can be lethal to people, animals, and plants. Just like earthquakes, violent volcanic eruptions may also happen underwater, which can trigger a tsunami.

Lesson 2: Plate Tectonics There are a few handfuls of major plates and dozens of smaller, or minor, plates. Six of the majors are named for the continents embedded within them, such as the North American, African, and Antarctic plates. Though smaller in size, the minors are no less important when it comes to shaping the Earth. The tiny Juan de Fuca plate is largely responsible for the volcanoes that dot the Pacific Northwest of the United States. The plates make up Earth's outer shell, called the lithosphere. (This includes the crust and uppermost part of the mantle.) Churning currents in the molten rocks below propel them along like a jumble of conveyor belts in disrepair. Most geologic activity stems from the interplay where the plates meet or divide. The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart; and transform, where plates move sideways in relation to each other. They move at a rate of one to two inches (three to five centimeters) per year. Convergent BoundariesWhere plates serving landmasses collide, the crust crumples and buckles into mountain ranges. India and Asia crashed about 55 million years ago, slowly giving rise to the Himalaya, the highest mountain system on Earth. As the mash-up continues, the mountains get higher. Mount Everest, the highest point on Earth, may be a tiny bit taller tomorrow than it is today. These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass. As the overlying plate lifts up, it also forms mountain ranges. In addition, the diving plate melts and is often spewed out in volcanic eruptions such as those that formed some of the mountains in the Andes of South America. At ocean-ocean convergences, one plate usually dives beneath the other, forming deep trenches like the Mariana Trench in the North Pacific Ocean, the deepest point on Earth. These types of collisions can also lead to underwater volcanoes that eventually build up into island arcs like Japan. Divergent Boundaries At divergent boundaries in the oceans, magma from deep in the Earth's mantle rises toward the surface and pushes apart two or more plates. Mountains and volcanoes rise along the seam. The process renews the ocean floor and widens the giant basins. A single mid-ocean ridge system connects the world's oceans, making the ridge the longest mountain range in the world. On land, giant troughs such as the Great Rift Valley in Africa form where plates are tugged apart. If the plates there continue to diverge, millions of years from now eastern Africa will split from the continent to form a new landmass. A mid-ocean ridge would then mark the boundary between the plates. Transform Boundaries The San Andreas Fault in California is an example of a transform boundary, where two plates grind past each other along what are called strike-slip faults. These boundaries don't produce spectacular features like mountains or oceans, but the halting motion often triggers large earthquakes, such as the 1906 one that devastated San Francisco.

Pressure, or decompression, enables the mantle rock to melt and form magma. Decompression melting often occurs at divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure. The rock then cools into new crust. Decompression melting also occurs at mantle plumes, columns of hot rock that rise from Earth's high-pressure core to its lower-pressure crust. When located beneath the ocean, these plumes, also known as hot spots, push magma onto the seafloor. These volcanic mounds can grow into volcanic islands over millions of years of activity. Transfer of Heat Magma can also be created when hot, liquid rock intrudes into Earth's cold crust. As the liquid rock solidifies, it loses its heat to the surrounding crust. Much like hot fudge being poured over cold ice cream, this transfer of heat is able to melt the surrounding rock (the "ice cream") into magma. Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together. As the denser tectonic plate subducts, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc. Flux Melting Flux melting occurs when water or carbon dioxide are added to rock. These compounds cause the rock to melt at lower temperatures. This creates magma in places where it originally maintained a solid structure. Much like heat transfer, flux melting also occurs around subduction zones. In this case, water overlying the

Q3 SCIENCE 8 VOLCANO PLATE BOUNDARIES EARTHQUAKE

PLATE BOUNDARIES

Plate boundaries

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