seismograph - definition of seismograph in English | Oxford Dictionaries Definition of seismograph in English: seismograph An instrument that measures and records details of earthquakes, such as force and duration. Example sentences ‘Noaa would record the earthquake on seismographs and issue bulletins about the progress of a tsunami.’ ‘A series of digital seismographs installed around the volcano provide a continuous stream of data to the observatory.’ ‘Each country affected by the disaster is to set up a tsunami warning centre to receive information from the pressure gauges, seismographs and wave sensors that will survey the ocean basin.’ ‘Just as a scientist reads a seismograph to measure movements in the ground, the character of a government can be judged by the way it treats the most disadvantaged layers of society.’ ‘Tremors had been recorded in 1908 on a seismograph 4,000 kilometers west of St.

Petersburg.’ ‘Later, earthquake seismographs were developed that recorded digitally, and today virtually all modern seismic recordings are digital and thus involve some sort of signal processing.’ ‘This is similar to seismologists using seismographs on Earth to detect earthquakes.’ ‘Richter, who worked in southern California, using data from seismographs - which measure earth movement - devised a method to calculate where an earthquake began, or its epicenter, and its magnitude.’ ‘What comes out of the laboratory and what is measured in the real world by surface seismographs leaves a gap.’ ‘Aftershocks continued for several years, and small earthquakes still waggle seismographs in the region.’ ‘Since there were no seismographs operating in Alaska at that time and no reports of surface faulting in the remote Alaska Range, the location of the 1912 shock is poorly known.’ ‘Eventually the parties agreed on a strict monitoring plan relying on seismographs and strain gauges to assess the effect on the structure as crews installed the caissons.’ ‘All told, 1,200 seismographs - including 800 borrowed from the United States - are being used in the $423,000 project

.’ ‘The seismographs recorded the waves from that earthquake and from magnitude 2.1 and 2.8 earthquakes beneath the Cascade Mountains, even though the shaking was too small to be felt by residents.’ ‘A seismograph at Ferris High School showed the trembling lasted for more than 30 seconds with two distinct spikes in intensity.’ ‘With more earthquakes, more and better seismographs recording quakes, and more comprehensive compilations of seismic data, seismologists are sharpening their view of the African plume.’ ‘Traditional seismographs record straight-line movements, for example shaking, whereas ring lasers measure rotational movements like rolling or twisting.’ ‘A series of digital seismographs around the volcano provide a continuous stream of data to the observatory in Goma.’ ‘Old-style seismographs recorded the jiggling of an earthquake on a rotating drum.’ ‘The observatory contained a seismograph to record mining tremors, an evaporation pan and a device to record lightening strikes which are particularly virulent on the Witwatersrand.’ Pronunciation Which of the following is a type of wild cat?

cheater Which of the following is a type of wild cat? Pallas's cat Which of the following is a type of wild cat? polecat Which of the following is a type of wild cat? ring-tailed cat Which of the following is a type of wild cat? manul Which of the following is a type of wild cat? hunting cat Which of the following is a type of wild cat? ounce Which of the following is a type of wild cat? bandicoot Which of the following is a type of wild cat? clouded leopard Which of the following is a type of wild cat? puna You scored /10 practise again? Retry Most popular in the world Australia What is a Seismograph? - Definition, History & Facts - Video & Lesson Transcript | Study.com What is a Seismograph? - Definition, History & Facts Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Register for a free trial Are you a student or a teacher?

I am a student Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: What is an Earthquake? - Definition & Explanation You're on a roll. Keep up the good work! Your next lesson will play in 10 seconds 0:00 What's a Seismograph? 1:00 How a Seismograph Works 2:00 Measurement Scales Add to Add to Add to Want to watch this again later? Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Teachers Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Students Create a new course from any lesson page or your dashboard. From any lesson page: Click "Add to" located below the video player and follow the prompts to name your course and save your lesson.

From your dashboard: Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Personalize: Name your Custom Course and add an optional description or learning objective. Organize: Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Teacher Edition: Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. Premium Edition: You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course today Try it free for 5 days! Lesson Transcript Instructor: Mary Ellen Ellis Read about the seismograph, what it measures, how it works, and how it has helped scientists to better understand earthquakes both in the past and today. ​!!!What's a Seismograph? Earthquakes are fascinating and frightening at the same time. Have you ever wondered how scientists study these earth-shaking events?

They use what's called a seismograph, also called a seismometer, which is an instrument that measures and records seismic waves that move through the earth as the result of an earthquake. A modern seismograph can help scientists detect earthquakes and measure several aspects of the event: The time at which the earthquake occurred The epicenter, which is the location on the surface of the earth below which the earthquake occurred The depth below the earth's surface at which the earthquake occurred The amount of energy released by the earthquake Scientists measure and record this data to learn more about earthquakes, tectonic plates, and Earth's layers. Earthquakes are difficult to predict, but scientists studying them hope to use seismographic measurements to be able to make more accurate predictions. How a Seismograph Works The idea behind a seismograph is fairly simple. A basic seismograph includes a solid base and a heavy weight suspended from a spring over the base. A pen hangs from the weight and a rotating drum with paper sits below it on the base. The tip of the pen touches the drum. When the earth shakes from an earthquake, the drum rotates and the weighted pen moves back and forth due to the motion of seismic waves. The pen records the movement on the drum.

The paper recording of an earthquake is called a seismogram. The most high-tech seismographs used by scientists studying earthquakes today are sophisticated and precise. They are based on the same concept as a basic, simple seismograph, but make use of electronics, magnets, and amplifiers in order to accurately and precisely measure the smallest ripples in the earth caused by earthquakes. Measurement Scales You have probably heard of the Richter scale, a popular unit for measuring the magnitude of an earthquake. It was invented by Charles F. Richter of the California Institute of Technology in 1935 and uses a logarithmic scale to measure seismic wave magnitude. Because the scale is logarithmic, a difference of one unit represents a tenfold difference in the magnitude of a seismic wave. For instance, an earthquake measured as 6.0 on the Richter scale is 10 times more intense than a 5.0 earthquake. A 7.0 earthquake is 100 times more intense than the 5.0 earthquake. The Richter scale is still often cited in news reports of earthquakes, but scientists studying these events use another scale that allows for more accurate measurements.

This is called the moment magnitude scale and it can be applied to a wider range of types and sizes of earthquakes. It is logarithmic, like the Richter scale, and similar to the older scale for earthquakes up to about a magnitude of 8.0. For larger quakes, the moment magnitude scale begins to differ from the Richter scale and provides more accurate measurements. × Earthquake | Seismology, magnitude and other units of measurement Earthquakes: seismology & measurement Seismology As we have seen, most earthquakes are essentially the product of tectonic stresses which are generated at the boundaries of the Earth's tectonic plates . The released energy travels as shock waves, called seismic waves , which may be felt and measured. The study of seismic waves is known as seismology, a word derived from a Greek word meaning "to shake." Seismographs are the instruments which record earthquakes. Scientists use these instruments as their principal tool to study seismic waves. They are very sensitive instruments that can detect, measure and record ground vibrations and their intensities during an earthquake. A seismograph is a simple pendulum. As the ground shakes the base and frame move with the vibrations but inertia keeps the pendulum bob in place.

It moves relative to vibrating ground. The pendulum displacement records the changes over time the tracing out the record of the event is called a seismogram. Image: A seismograph The image above shows the seismograph in Sunset Crater Volcano National Monument's visitor centre. A pen at the top of the device records a zig-zag line on the moving, paper-covered cylinder whenever an earthquake is detected. The seismogram (paper record) is removed each day and replaced. The earthquake data from the seismogram is then analyzed by scientists. Seismographs can help us determine the time, epicentre , focus , and the type of faulting which produced an earthquake as well as estimate how much energy was released. Magnitude and other units of measurement The severity of an earthquake can vary from events which are barely detectable even using the most sophisticated devices, to devastating events which can level cities and trigger Tsunamis and sometimes even volcanic activity. The severity of an earthquake is called its magnitude. Various scales were proposed to measure the magnitude of earthquakes until 1935, when the Richter Scale was developed by a seismologist named Conrad Richter to measure the intensity of the seismic waves.

The amplitude (height) of the largest recorded wave of an earthquake at a specific distance is called the Richter magnitude. Under the Richter scale, each order of magnitude is 10 times more intensive than the last one, which means that a two is 10 times more intense than a one and a three is one hundred times greater. But it is to point out that, while it is correct to say that for each increase in 1 in the Richter magnitude there is a tenfold increase in amplitude of the wave, it is incorrect to say that each increase of 1 in Richter magnitude represents a tenfold increase in the size of the earthquake (as is commonly incorrectly stated by the press). A better measure of the size of an earthquake is the amount of energy released by the earthquake, which is related to the Richter Scale by the following equation: log E = 11.8 + 1.5 M where Log refers to the logarithm to the base 10, E is the energy released in ergs and M the Richter magnitude.

Image: Earthquake Severity - Richter Scale Tectonic earthquakes can range in size from magnitudes less than zero, resulting from fault slippage of a few centimetres, to the largest events (magnitude greater than 9), where fault displacements are on the order of many metres. Earthquake size is determined not only by amount of displacement but also area of the ruptured fault plane. Hence the larger the rupture area, the larger is the earthquake. A magnitude 7 earthquake ruptures a fault area of about 1000 km2 or about 50 km long and 20 km wide. Also depth is an important factor influencing earthquake severity. We know that earthquakes can originate at various depths within the Earth’s solid core. The deeper the earthquake, the more powerful it is, but it is also far less likely to reach the surface. That’s why shallow earthquakes are more common and more dangerous, because the shallower an earthquake, the more damage to surface structures it can cause. There is no limit to the possible magnitude of an earthquake but historically just over magnitude 9 is the record. The earthquake of most recent history to reach 9 on the Richter scale was the Japan quake of March 2011.

This was also the largest recorded Japanese earthquake of all time. Image: Earthquake in Japan, March 2011 How does a seismograph work? What is the Richter scale? | HowStuffWorks How does a seismograph work? What is the Richter scale? Jason Reed/ Getty Images A seismograph is the device that scientists use to measure earthquakes. The goal of a seismograph is to accurately record the motion of the ground during a quake. If you live in a city, you may have noticed that buildings sometimes shake when a big truck or a subway train rolls by. Good seismographs are therefore isolated and connected to bedrock to prevent this sort of "data pollution." The main problem that must be solved in creating a seismograph is that when the ground shakes, so does the instrument. Therefore, most seismographs involve a large mass of some sort. You could make a very simple seismograph by hanging a large weight from a rope over a table. By attaching a pen to the weight and taping a piece of paper to the table so that the pen can draw on the paper, you could record tremors in the Earth's crust (earthquakes).

If you used a roll of paper and a motor that slowly pulled the paper across the table, you would be able to record tremors over time. However, it would take a pretty large tremor for you to see anything. In a real seismograph, levers or electronics are used to magnify the signal so that very small tremors are detectable. A big mechanical seismograph may have a weight attached that weighs 1,000 pounds (450 kg) or more, and it drives a set of levers that significantly magnify the pen's motion. Up Next How Volcanoes Work The Richter scale is a standard scale used to compare earthquakes. It is a logarithmic scale, meaning that the numbers on the scale measure factors of 10. So, for example, an earthquake that measures 4.0 on the Richter scale is 10 times larger than one that measures 3.0. On the Richter scale, anything below 2.0 is undetectable to a normal person and is called a microquake. Microquakes occur constantly. Moderate earthquakes measure less than 6.0 or so on the Richter scale.

Earthquakes measuring more than 6.0 can cause significant damage. The biggest quake in the world since 1900 scored a 9.5 on the Richter scale. It rocked Chile on May 22, 1960. 1 Measuring Earthquakes Measuring Earthquakes ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Seismologists use two main devices to measure an earthquake: a seismograph and a seismoscope.ï¿½ The seismograph is an instrument that measures seismic waves caused by an earthquake.ï¿½ The seismograph has three main devices, the Richter Magnitude Scale, the Modified Mercalli Intensity Scale, and the Moment-Magnitude Scale.ï¿½ The seismoscope is an instrument that measures the occurrence or the time of an occurrence of an earthquake (ï¿½Inventorsï¿½).ï¿½ Unlike other measuring devices, the seismoscope is a simple device without any technological background.ï¿½ The seismoscope is the oldest and most accurate instrument for measuring direction.

ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ First invented in 132 AD, the Dragon Jar was the first instrument for determining the direction of an earthquake.

ï¿½(Photo by Peter Bormann).ï¿½ Chang Heng, a Chinese scientist, developed the Dragon Jar.ï¿½ The Dragon Jar consists of a large jar with eight dragons protruding around the top.ï¿½ Each dragonhead holds a ball in its mouth while a frog sits with its mouth open directly underneath.ï¿½ Behind each dragonhead lies a trigger.ï¿½ Down the center of the jar is a thin stick that is loosely secured.ï¿½ The tremors of an earthquake cause the stick to fall on one of the eight triggers.ï¿½ When the trigger is set off, the dragonhead linked to the trigger drops the ball into the frogï¿½s mouth.ï¿½ The sound of the ball dropping into the frogï¿½s mouth indicated an earthquake had just occurred.ï¿½ By looking at which ball dropped, the direction of the earthquake could be determined.ï¿½ Hengï¿½s seismoscope was not only the first seismoscope but also very accurate and precise.ï¿½ In 138 AD, Hengï¿½s seismoscope detected an earthquake 1,000 miles away (ï¿½Chineseï¿½

).ï¿½ Wang Zhenduo recreated Chang Hengï¿½s seismoscope in 1951.ï¿½ Instead of a thin stick loosely secured in the center of the jar, Zhenduo replaced it with a copper pendulum shaft that connected to eight copper arms (ï¿½Zhang Hengï¿½).ï¿½ Like the seismoscope, other devices used to gather information on earthquakes were also first developed outside the United States .

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Nicholas Cirillo developed the first mechanical device used to study earthquakes in 1731.ï¿½ A series of earthquakes in Naples inspired Cirillo to design this mechanical device.ï¿½ Cirilloï¿½s device consisted of a pendulum that swung freely.ï¿½ The tremors of the earthquake caused the pendulum to swing.ï¿½ The lines caused by the pendulum indicated the amplitude of the ground motion.ï¿½ In Calabria , Italy , a series of earthquakes in 1783 that killed over 50,000 civilians.ï¿½ Because of these earthquakes, more mechanical devices were created (Kauffman and Judson 181). ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ D.

Domenico Salsano, a clockmaker and mechanic, invented a similar device to Nicholas Cirillo.ï¿½ Salsanoï¿½s device was a long pendulum with a brush connected at the tip.ï¿½ The brush would then trace the motions of the earthquakeï¿½s tremors with slow-drying ink onto an ivory slab.ï¿½ Salsanoï¿½s device had a bell attached that rang when the tremors were large enough (Kauffman and Judson 181).ï¿½ James Forbes also created a similar mechanical device.ï¿½ His device was called the ï¿½Inverted-pendulum Seismometer.ï¿½ï¿½ This device was a metal rid with a movable base (Kauffman and Judson 181).ï¿½ Later in 1855, Luigi Palmier of Italy designed a mercury seismometer.

The mercury seismometer had U-shaped tubes filled with mercury and arranged along the compass points.ï¿½ When an earthquake occurred, the movement of the mercury made an electrical contact that stopped a clock and started the recording drum.ï¿½ The motion of a float on the surface of mercury was recorded on the drum.ï¿½ Palmierï¿½s seismometer was the first device to accurately record the time and of an earthquake while also recording the duration and the intensity of the earthquake (ï¿½Inventorsï¿½).ï¿½ The instruments used to gather information on earthquakes are seismographs.

ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ In 1880 John Milne, an English seismologist and geologist, is credited for the development of the first modern seismograph in 1880.ï¿½ Milne called his seismograph the ï¿½Horizontal seismographï¿½ (ï¿½Inventorsï¿½).ï¿½ Milneï¿½s seismograph consists of three parts: the inertia member, the transducer, and a recorder.ï¿½ ï¿½(Drawing by Professor Stephen A.

Nelson)ï¿½ The inertia member is a weight suspended by a wire or a spring.ï¿½ It is similar to a pendulum; however, it can only swing in one direction.ï¿½ The transducer is a device that detected the motion between the mass and the ground.ï¿½ This motion is then converted into a form that can be recorded.ï¿½ The transducer can be a mechanical lever or an electrodynamic system.ï¿½ In an electrodynamic system, a coil of wire moved back and forth in a magnetic field.ï¿½ This movement created an electric current that passed through a galvanometer then recorded on a sheet of paper (Kauffman and Judson 182).ï¿½ Sir James Alfred Ewing, Thomas Grey and John Milne founded the Seismological Society of Japan .ï¿½ The society funded the invention of seismographs (ï¿½Inventorsï¿½).

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The Horizontal Pendulum seismograph was improved after World War II.ï¿½ The new device is called the Press-Ewing seismograph.ï¿½ The Press-Ewing seismograph is widely used throughout the United States to record long period waves.ï¿½ The difference between the Press-Ewing and the Horizontal pendulum seismograph is that the Press-Ewing seismograph has a pivot that hold the pendulum was replaced with elastic wire to avoid friction (ï¿½Inventorsï¿½).ï¿½ The design of a seismograph is a weight freely suspended from a support that is attached to bedrock.ï¿½ When the seismic waves reached the seismograph, the inertia of the weight kept the device stable while the ground and support shake.ï¿½ The movement of the ground in relation to the movement of the weight it recorded onto a piece of paper that is wrapped around a rotating drum (Lutgens and Edwards 306).ï¿½ To record motion in all directions, three seismographs are required.ï¿½ One

 seismograph is needed to measure vertical motion, and two to record horizontal motion.ï¿½ The two seismographs recording horizontal directions, record in 90-degree angles (Kauffman and Judson 182).

ï¿½ Seismographs record in a zigzag trace that shoes the varying amplitude of ground oscillations beneath the instrument.ï¿½ Depending on the sensitivity of the seismograph, earthquakes can be detected anywhere in the world.ï¿½ Using data collected by the seismographs, the time, location, and the magnitude can be determined (Bellis).ï¿½ The magnitude of an earthquake can be determined by a mathematical formula called the Richter Magnitude Scale.ï¿½ï¿½ï¿½ Charles F.

Richter developed the Richter Magnitude Scale in 1934.ï¿½ Richter defined the scale as ï¿½The logarithm to base 10 of the maximum seismic wave amplitude recorded on a standard seismograph at a distance of 100 kilometers from the earthquake epicenter.ï¿½ï¿½ The seismic wave used in the calculation is not specified (Bolt 104).ï¿½ï¿½ï¿½ Because it is not specified, S waves or P waves can be used.ï¿½ The Richter scale was originally designed by Richter to differentiate between earthquakes with a low focus point in southern California .ï¿½ The Richter scale is referred to ML, with ï¿½Lï¿½ for local.ï¿½ After many seismograph stations were established, it became clear the formula was only valid for a certain frequency and distance ranges (ï¿½Measuring Earthquakesï¿½).ï¿½ The original scale was modified to measure earthquakes at any distance, focal depth and compensate for geological variations from place to place (Lutgens and Edwards).ï¿½ Adjustments were also included into the formula to compensate for the variation of the distance

 between different seismographs (ï¿½Severityï¿½).ï¿½ Reading the Richter scale is a difficult task to accomplish.ï¿½ Each whole number increase in the scale releases 32 times more energy than the preceding number ( U.S.

Geological Survey).ï¿½ Although this process seems simple, it is actually very complex.ï¿½ Seismologists are given seismograms then had to determine the magnitude at its source.ï¿½ Earthquakes with a magnitude of 2.0 or less are called microearthquakes (Bellis).ï¿½ The Richter scale has no upper limit.ï¿½ Although the largest earthquake is recorded to be an 8.9, it is possible the earth can withstand the stress to produce an earthquake larger than 9.0 (McConnel).ï¿½ According to the chart, large earthquakes will be felt by everyone and even cause serious damage.ï¿½ However, people may not feel some large-magnitude earthquakes beneath the ocean at all (Bellis). Richter magnitude Great earthquake. Can cause serious damage in areas several hundred kilometers across.

(ï¿½Intensityï¿½)ï¿½ Like the Richter scale, the Modified Mercalli Intensity Scale measures an earthquake at its source so where the measurement is made is insufficient (ï¿½Measuring Earthquakesï¿½).ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ American seismologists Harry Wood and Frank Neumann developed the Modified Mercalli Intensity Scale in 1931.ï¿½ Wood and Neumann extended the Modified Mercalli Intensity Scale to twelve Roman Numerals instead of the original ten.ï¿½ Unlike the Richter scale, the modified Mercalli scale ranks bases on observed effects.ï¿½ The effect an earthquake has on a particular area of land is the intensity of the earthquake.ï¿½ These effects range from waking people up to complete destruction (ï¿½Severityï¿½).ï¿½ I strong People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks fall from buildings. Damage is slight to moderate in well-built buildings; considerable in poorly built buildings. VIII violent Drivers have trouble steering.

Houses that are not bolted down might shift on their foundations. Tall structures such as towers and chimneys might twist and fall. Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Tree branches break. Hillsides might crack if the ground is wet. Water levels in wells might change. IX disastrous Well-built buildings suffer considerable damage. Houses that are not bolted down move off their foundations. Some underground pipes are broken. The ground cracks. Reservoirs suffer serious damage. X most disastrous Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, lakes. The ground cracks in large areas. Railroad tracks are bent slightly. XI catastrophic Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground. Underground pipelines are destroyed. Railroad tracks are badly bent. XII great catastrophe Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.

(ï¿½Intensityï¿½)ï¿½ After the occurrence of an earthquake, the Geological Survey mails questionnaires to post offices in that particular area.ï¿½ The questionnaires are distributed to everyone in that area requesting information about the earthquakeï¿½s damage.ï¿½ That information is used to create an isoseismal math that shows the various levels of intensity in that area (ï¿½Severityï¿½).ï¿½ The Modified Mercalli Scale however does have its dependencies: population density, building methods and materials, and distance from the epicenter.ï¿½ The intensity of an earthquake can be underestimated in an area that is densely populated.ï¿½ The amount of damage done by earthquakes depends on how well a building is built.ï¿½ The building methods and materials used to build the structures affect how much damage is caused.ï¿½ This variance in damage could give the same earthquake a different intensity value.ï¿½ An area farther from the epicenter will receive less damage than closer areas.ï¿½ Because each area has a different intensity value, it is difficult to compare individual results (McConnel).ï¿½ Moment magnitude is similar to Modified Mercalli Scale however is based on physical changed of

 the earth.

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ The moment magnitude is based on the amount of displacement that occurred along a fault zone rather than the measurement of ground motion at a given point (Lutgens and Edwards 314).ï¿½ The Moment magnitude measures energy released by the earthquake more accurately than the Richter scale.ï¿½ The amount of energy released is dependent of a rockï¿½s properties, area of the fault surface, and amount of movement along the fault zone (McConnel).ï¿½ Seismologists calculate Moment magnitude from seismograms after long-period waves are examined (Lutgens and Edwards 314).ï¿½ Moment magnitude is calculated with more accuracy with large earthquakes (McConnel).ï¿½ Moment magnitude gained support and acceptance among many seismologists and engineers.ï¿½ Seismologists and engineers accepted Moment Magnitude because: 1) It is the only magnitude scale that adequately measures the size of large earthquakes 2) It is a measure established from the size of the rupture surface and the amount of displacement, which better determines the amount of

 energy released 3) It can be verified by two different methods, field studies that are based of measurements of fault displacement and by seismograph methods that uses long-period waves (Lutgens and Edwards 314).

Displacement is the measurement of the actual change of location of the ground due to shaking (ï¿½Measuring Earthquakesï¿½).

Earthquakes in occur mainly in the Northeast.ï¿½ Since 1830, the Arizona and Cataract Creek.ï¿½ Many earthquakes occurred in southern Arizona as well.ï¿½ Yuma is recorded to have had dozens of earthquakes in the last 175 years that occurs fairly regularly.ï¿½ AEIC recorded the location of a numerous earthquakes simply as SW Arizona .ï¿½ Because AEIC did not specify which area in SW Arizona, Sierra Vista may have had earthquakes in the past or recently.ï¿½ In the last ten years at least, Sierra Vista has not experienced an earthquake that people have felt.ï¿½ A slammed car door, vehicles colliding with each other, or building being built is the closest event Sierra Vista has experienced to an earth ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿

½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Works Cited Arizona Earthquakes 1830-2005.ï¿½ 10 Jan 2005.ï¿½ Arizona Intensity of the Earthquake.ï¿½ 2005.ï¿½ THEmeter.ï¿½ 24 April 2005 ï¿½ï¿½ Kauffman, Marvin E.

and Sheldon Judson.ï¿½ Physical Geology.ï¿½ 8th ed Prentic Hall: New Jersey .ï¿½ 1990. Lutgens, Fredrick K. and Tarbuck J Edwards.ï¿½ Essentials of Geology.ï¿½ 8th ed.ï¿½ Prentic Hall: New Jersey .ï¿½ 2003. McConnel, David.ï¿½ Earthquakes II.ï¿½ 14 Jan 1997.ï¿½ Natural Science Geology.ï¿½ 258 Mar 2005. < > Measuring Earthquakes.ï¿½ 2001.ï¿½ SKLPC.ï¿½ 21 Apr 2005.ï¿½ Nelson, Stephen A.

Professor.ï¿½ Earthquakes.ï¿½ 23 Oct 2003.ï¿½ Tulane .ï¿½ 24 April 2005 ~sanelson/geol111/earthint.htm The Severity of an Earthquake.ï¿½ 29 Sep 2004.ï¿½ U.S. Geological Survey.ï¿½ 25 Mar 2005. < > Zhang Heng. Albertsons: Seismograph: Horizontal- Incorporated Research Institutions for Seismology Seismograph: Horizontal How does a seismometer measure horizontal ground motion? Animation of the principles of a drum-style horizontal seismograph station that records back- and-forth (N‚ÄìS, E‚ÄìW) movement. The suspended mass remains at rest as the spring and pivoting knife absorb most of the motion during an earthquake. The instrument shifts back and forth due to the oblique travel direction of the P wave and the shearing movement of the S wave. The stylus (pen) affixed to the mass, records the relative motion between itself and the rest of the instrument, thus recording the ground motion.

Keypoints: Seismograph station records Earth's movement. The suspended mass remains at rest as the spring and pivoting knife absorb most of the motion during an earthquake. The instrument shifts back and forth due to the oblique travel direction of the P wave and the shearing movement of the S wave. The stylus (pen) affixed to the mass, records the relative motion between itself and the rest of the instrument, thus recording the ground motion. Total Time: 19s Seismic waves travel through the earth to a single seismic station. Scale and movement of the seismic station are greatly exaggerated to depict the relative motion recorded by the seismogram as P, S, and surface waves arrive. Animation | Novice 3-Component Seismogram Records Seismic-wave Motion We use a cow and a tree in this narrated cartoon for fun and to emphasize that seismic waves traveling away from an earthquake occur everywhere, not just at seismic stations. Watch them shake as they are struck by incoming P, S, and Surface waves.

Animation | Novice 4-station Seismograph Network Records a Single Earthquake A cow and a tree in this narrated cartoon for fun and to emphasize that seismic waves traveling away from an earthquake occur everywhere, not just at seismic stations A, B, C, and D. A person would feel a large earthquake only at station A near the epicenter. Stations B, C, D, and the cow are too far from the earthquake to feel the seismic waves though sensitive equipment records their arrival. Animation | Novice Seismograph an instrument that records the seismic waves of - GEOL - 1001 Seismograph – an instrument that records the seismic waves of an earthquake. Seismic waves P waves – are compressional waves. They travel through solids, liquids, and gases. They are push-pull waves. This preview has intentionally blurred sections. Sign up to view the full version. View Full Document Chapter 13: Earthquakes 16:29 S waves – are shear waves. Travel through solid rock, but not liquids or gases. They displace material at right angles to the direction of propagation. L waves or surface waves – are confined to Earth’s surface. They are like waves on the ocean. Most destructive.

They make the ground roll, and they make it shake from side to side. Figure 13.5 page 303 Locating an epicenter The time interval between the arrival of P and S waves depends on the distance the waves have traveled from the focus. Measuring the size of an earthquake Richter magnitude – in 1935, Charles Richter, a California seismologist, devised a simple procedure to determine the size of an earthquake. The logarithm of the largest ground motion registered by a seismograph as his measure of earthquake size. He accounted for the distance between the seismograph and the fault rupture by correcting for the weakening of the seismic waves as they spread away from the focus. A magnitude 3 earthquake has ground motions 10 times larger than a magnitude 2 quake Each step of magnitude releases 33 times the energy of one below it: A magnitude 5 quake releases 33 time more energy than a 4 quake. Moment magnitude – scientists now use the “moment” of the earthquake to measure magnitude.

The moment of an earthquake is defined as the product of are and the average slip across the fault break; the corresponding moment magnitude increases by about one unit for every 10 fold increase in the area of faulting. (A 2 is 10x bigger than a one, a 3 is 100x bigger than a one…) It produces roughly the same results as magnitude, but it is more precise and accurate. Chapter 13: Earthquakes 16:29 Shaking intensity – earthquake magnitude does not describe fully the hazards of earthquakes. A magnitude 8 quake in a remote area is not going to cause much damage, while at 6 underneath a city will. Table 13.1 Modified Mercalli Intensity Scale Determining fault mechanisms from earthquake data The pattern of ground shaking also depends on the orientation of the fault rupture and the direction of slip, which together specify the fault mechanism of an earthquake. The fault mechanism tells us if the quake was caused by a normal, reverse, or strike-slip fault. It also tells if the fault was right lateral or left lateral if it was a strike slip fault. This preview has intentionally blurred sections. Sign up to view the full version.

Question: A seismograph is an instrument which measures and records details of what?
Answer: Earthquakes