Earthquakes - The Dynamic Earth
Precise definition of earthquakes:
Earthquake is a natural disaster that occurs when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault, also known as the fault plane. The area below the earth’s surface where the earthquake starts is called the hypocentre, and the area above it on the surface is called the epicentre.
More than a million earthquakes rattle the world each year. But, most are so small that they can only be detected by sensitive instruments called seismogram.
Scientific theory that explains why earthquake occurs:
The earth consists of four major layers: The inner core, outer core, mantle and crust. The crust and the top of the mantle make up a thin skin on the surface of the planet. However, the skin is not all in one piece; it is made up of several pieces, called tectonic plates. These huge plates are
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When a plate collides with another plate, pressure builds up until the rocks suddenly crack and shift.
The fractures that form between these shifting rocks are called faults. Not all faults are the same. There are three basic kinds: normal, thrust or reverse and transcurrent or strike-slip faults.
Normal fault is when the land on one side of the break slips downward, and so the land on other side is higher. Normal faults are currently forming in the Basin and Range region of the western United States. They are also responsible for the Sea of Cortez, or the Gulf of California, that separates Baja California from the rest of Mexico.
Thrust or reverse fault is when one block of crust is on top of another. These faults are commonly found in collisions zones, where tectonic plates -push up mountain ranges such as the Himalayas and the Rocky Mountains.
Strike-slip or the transcurrent fault is when two lands are sliding past each other horizontally, with little to no vertical
Earthquakes are best described as a shaking or vibration of the ground caused by breaking of rock. Sometimes they are very strong and other times you would hardly notice them. This shaking occurs when stress that builds up in the crust is suddenly released as the crust breaks free and/or slides against the other pieces of crust. Earthquakes may also be thought of as the breaking of a popsicle stick by applying pressure to both ends at the same time. Should you try this experiment , you will feel the pressure build up as you apply more force until the stick snaps. When the stick snaps you will feel an instant of pain at your fingers as the stress reduces and energy waves move throughout the stick. When the earth's crust is placed under similar types of stress, binding as the stress builds, it will also snap and release the energy into the surrounding rocks, 'ooch'. Thinking about earthquakes will become more clear if you try another experiment.
Earthquakes, by Webster’s dictionary definition, are, “a shaking or trembling of the earth that is volcanic or tectonic in origin.” World Book Encyclopedia reports scientists believe that more than 8,000 earthquakes occur each day without causing damage. A little more than 1,000 each year are strong enough to be felt. Earthquakes occur in the general sense, anywhere on land. Other earthquakes go by different names, such as volcanic eruptions and tsunamis, large tidal wave storms that occur underwater, primarily in the Pacific Ocean.
The earth is split into four layers, inner and outer core, the mantle and crust. The top of the mantle and crust make up what is like the skin of our earth (see source 2). The skin is split up like a puzzle and we call these puzzle pieces’ tectonic plates (see source 1). These plates are constantly moving and the plate boundaries (edges of the plates) move and slide past one another. Sometimes as the plates move the plate boundaries become stuck. Pressure builds up in the stuck area over time and eventually breaks. This is why earthquakes occur due to the sudden movement of the plate sliding and breaking creating a fault line to go off. The fault line is the line on which the
The San Andreas Fault Line, first identified in 1895 by Professor Andrew Lawson of UC Berkeley, is an 800-mile fracture in the Earth’s surface, stretching from the Gulf of California to San Francisco, and is one of the longest faults in the world. It forms the boundary between the Pacific Plate and the North American Plate, with a complex network of smaller faults branching off the main San Andreas line which are responsible for a majority of the areas earthquakes.
...tectonic movement of the plates, the stress forms along the fault and ultimately releases as an earthquake. On the pacific plate, Transform boundary along with the San Andreas fault. Transform-fault boundaries is when two plates that slide horizontally past another. Transform boundaries are usually found on ocean floor, but a few occur on the land. San Andreas fault zone is a transform fault, which connects East Pacific rise, in the south a divergent boundary, with South Gorda-Juan de Fuca-Explorer Ridge, yet another divergent boundary to the North. Ultimately because it’s a transform boundary, convergent boundary is strike-slipping past each of the plates in order to release pressure. As the San Andreas Fault is prime transform boundary between the North American Plate and the Pacific Plate, the Hayward Fault assumes a share of the total motion between the plates.
The interior structure of Earth is chemically divided into an outer solid crust, the mantle, a liquid outer core, and a solid inner core. The core is largely composed of iron, along with nickel and silicon. Other lighter elements are usually in the crust.
The plate tectonic theory is a theory that geologists use to help explain the Earth’s surface processes and events. It explains that the sliding of these plates are either away from each other, sliding past each other, or sliding into each other and causing one of the plates to slide beneath the other. There are three kinds of plate tectonic boundaries: divergent, convergent, and transform plate boundaries. A divergent boundary occurs when two tectonic plates move away from each other. Magma then flows up from the mantle to fill in the space between the plates, forming a raised ridge called a mid-ocean ridge. The magma also spreads in the exterior, forming new ocean floor and new oceanic crust. A convergent boundary occurs when two plates
Mr. Adams describes the San Francisco earthquake as his most profound human suffering experience because the horror of shaking floors, parts of his mom’s house collapse to the floor, and got a broken nose from stumbling into a brick wall (Ansel Adams & The 1906 Earthquake 2008). Earthquakes are part of natural disasters of the earth and normally caused by shaking ground and rapid movement of one block of rock slipping past another a long fractures in the earth crust called faults. Faults that are usually locked excluding abrupt movements, which slippage creates an earthquake (Lutgens, F. & Tarbuck, E.
What are earthquakes? An earthquake is what happens when two pieces of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane. The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter, or focus.
Geologists today define an earthquake as the shaking and the trembling of the earth’s surface, known as the ground. Earthquakes are caused by the sudden release of energy, usually as a result of faulting which involves displacements of rocks along fraction. All of this energy has been building up for a long period of time and then suddenly just blows.
Before examining the Northridge event, understanding the naturally occurring hazard that is an earthquake will help to better understand exactly what happened and why it was such an important geological event. With four distinct layers, two layers, the crust and upper portion of the mantle, compose the skin that is the surface layer of the Earth. The crust is not a single, continuous piece. It is actually several different pieces, or plates, that come together to form the puzzle that comprises the surface of the Earth. These plates are in constant motion rubbing against one another. These areas, known as fault lines, where the plates rub up against one another have spots where one plate ”gets stuck while the rest of the plate keeps moving. When the plate has moved far enough, the edges unstick and is how most of the earthquakes around the world occur” (Wald, 2012). The energy stored from the friction of the two plate...
Additionally, this earthquake occurred on a thrust fault. This fault was a subduction zone slip which occurred primarily beneath the ocean were the Pacific plate plunges underneath the North American plate. This sudden upward movement of the sea floor along the rupturing fault generated a massive tsunami. This vertical deformation
The San Andreas Fault is a geologic fault zone between two tectonic plates that runs from San Francisco south to San Diego in California. It is an area of frequent earthquakes caused by the plates sliding past each other. It is so called because it runs along the San Andreas Valley.
Earthquakes belong to the class of most disastrous natural hazards. They result in unexpected and tremendous earth movements. These movements results from dissemination of an enormous amount of intense energy in form of seismic waves which are detected by use of seismograms. The impact of earthquakes leaves behind several landmarks including: destruction of property, extensive disruption of services like sewer and water lines, loss of life, and causes instability in both economic and social components of the affected nation (Webcache 2).
They are the earth’s crust; they move very slowly every year. As the tectonic plates slide over each other they cause earthquakes. Earthquakes produce various damaging effects this includes damage to structures of buildings, bridges and other standing formations which then...