What is a seismogram?
112332
It's a read-out from a Seismometer\n---------------------------\nSeismometer (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record seismic waves. By studying seismic waves, geologists can map the interior of the Earth, and measure and locate earthquakes and other ground motions. The term seismograph is usually interchangeable, but seismometer seems to be a more common usage.\n\nThe seismometer was first invented by Zhang Heng in China in 132AD.\n\nLater John Milne invented the horizontal pendulum seismograph at the Imperial College of Engineering in Japan in 1880. This marked the beginning of modern seismology.\n\nBasic principles\nSeismometers have:\n\nA frame securely affixed to the earth. The foundation is critical, and often the most expensive part of a seismic station. \nAn inertial mass suspended in the frame by some method, using springs or gravity to establish a steady-state reference position. \nA damper system to prevent long term oscillations in response to an event. \nA means of recording the motion of the mass relative to the frame. Early seismometers used optics, or motion-amplifying mechanical linkages, while modern instruments use electronic amplification of signals generated by position or motion sensors. \nPassing seismic waves move the frame, while the mass tends to stay in a fixed position due to its inertia. The seismometer measures the relative motion between the frame and the suspended mass.\n\nProfessional seismic observatories usually have instruments measuring three axes, north-south, east-west, and up-down. Seismologists generally prefer a vertical seismograph if only one instrument is available.\n\nA professional station is sometimes mounted on bedrock with an uncracked connection to a continental plate. The best mountings may be in deep boreholes, which avoid thermal effects, ground noise and tilting from weather and tides. Amateur, or less exotic instruments are often mounted in insulated enclosures on small buried piers of unreinforced concrete. Reinforcing rods and aggregates would distort the pier as the temperature changes. A site should always be surveyed for ground noise with a temporary installation before pouring the pier and laying conduit.\n\nAn early example\nThe principle can be shown by an early special purpose seismometer. This consisted of a large stationary pendulum, with a stylus on the bottom. As the earth starts to move, the heavy mass of the pendulum has the inertia to stay still in the non-earth frame of reference. The result is that the stylus scratches a pattern corresponding with the earth's movement. This type of strong motion seismometer recorded upon a smoked glass (glass with carbon soot). While not sensitive enough to detect distant earthquakes, this instrument could indicate the direction of the initial pressure waves and thus help find the epicenter of a local earthquake — such instruments were useful in the analysis of the 1906 San Francisco earthquake. Further re-analysis was performed in the 1980s using these early recordings, enabling a more precice determination of the initial fault break location in Marin county and its subsequent progression, mostly to the south.\n\nEarly Designs\nAfter 1880, most seismometers were descended from those developed by the team of John Milne, James Alfred Ewing and Thomas Gray, who worked together in Japan from 1880-1895. These seismometers used damped horizontal pendulums. Later, after World War II, these were adapted into the widely-used Press-Ewing seismometer.\n\nLater, professional suites of instruments for the world-wide standard seismographic network had one set of instruments tuned to oscillate at fifteen seconds, and the other at ninety seconds, each set measuring in three directions. Amateurs or observatories with limited means tuned their smaller, less sensitive instruments to ten seconds.\n\nThe basic damped horizontal pendulum seismometer swings like the gate of
145283
Paper (1st century AD)\nCompass (3nd century AD)\nGunpowder(9th century AD)\nSeismometer (to measure earthquakes, 1st century AD)\nStirrups (5th century AD)\nCrossbow (2nd century AD)
274866
this site is the best\nhttp://earthquake.usgs.gov/learning/
371029
Seismic Waves are the different waves that travel through the earth surface from an earthquake.  There are 2 major waves or movements observed on the surface.\n1.  P waves (compression waves) move the surface form side to side and create cavities in the ground.\n2.  S waves (shear waves) move the surface up & down creating ridges and cliffs in the surface.\n\nBS Geology Degree
1000927
maybe this will help you.\n\nhttp://www.scarborough.k12.me.us/wis/teachers/dtewhey/webquest/nature/seismic_waves.htm
939929
A gravimeter is a device designed to measure the local gravitational field. Also sometimes called a gravitometer, a gravimeter is a type of accelerometer. According to the equivalence principle of Albert Einstein, the effects of a gravitational field are rigorously equivalent to acceleration. Therefore, gravimeters are susceptible to vibration which causes small, oscillatory accelerations. This is counteracted by integral vibration isolation and signal processing.
409571
The exact location of an earthquake.
910772
By analyzing the frequency ,arrival time and various components of the seismograph recorded during earthquakes. Different types of density of layers conduct the waves in different types. You can compare with non destructive type of metal testing by spectrogram method.
396939
Sonogram. Ask your doctor about it.
276691
The USGS has diagrams of earthquake faults and what they look like during a quake.\n\nThe National Park Service has a good map of the various plates that make up the Earth's crust.
90855
Main methods --\n(1)studying the patterns of vibrational echoes returned from surface and subsurface man-made explosions;\n(2)studying data gathered by instruments during earthquakes;\n(3)studying volcanic materials
250606
Richter Scale is not a machine. It is the system used to measure the strength of an earthquake. Developed by Charles Richter in 1935 as a means of categorizing local earthquakes. It is a collection of mathematical formulas; it is not a physical device. It is a logarithmic scale for measuring earthquake magnitude which means that, a magnitude 7.0 earthquake generates 10 times larger amplitude waves than those of a magnitude 6.0, and releases 32 times more energy. The machine that measures earthquakes is called a Seismograph.
685931
http://earthquake.usgs.gov/eqcenter/recenteqsww/
626571
congratulations .. u've become the official human seismograph!! pls contribute ur services to humanity
55918
An earthquake is the shaking of the ground caused by an abrupt shift of rock along a fracture in the Earth, called a fault. Within seconds, an earthquake releases stress that has slowly accumulated within the rock, sometimes over hundreds of years. ... \nThe size of an earthquake is indicated by a number called its magnitude. Magnitude is calculated from a measurement of either the amplitude or the duration of specific types of recorded seismic waves. Magnitude is determined from measurements made from seismograms and not on reports of shaking or interpretations of building damage. ... The intensity of and earthquake is a measure of the amount of ground shaking at a particular site, and it is determined from reports of human reaction to shaking, damage done to structures, and other effects. ... \n\nEarth scientists believe that most earthquakes are caused by slow movements inside the Earth that push against the Earth's brittle, relatively thin outer layer, causing the rocks to break suddenly. This outer layer is fragmented into a number of pieces, called plates. Most earthquakes occur at the boundaries of these plates. In Washington State, the small Juan de Fuca plate off the coast of Washington, Oregon, and northern California is slowly moving eastward beneath a much larger plate that includes both the North American continent the land beneath part of the Atlantic Ocean. Plate motions in the Pacific Northwest result in shallow earthquakes widely distributed over Washington and deep earthquakes in the western parts of Washington and Oregon. The movement of the Juan de Fuca plate beneath the North America plate is in many respects similar to the movements of plates in South America, Mexico, Japan, and Alaska, where the world's largest earthquakes occur. ...
460913
structures are subjected to 2 types of movement in an earthquake, P-wave and S-wave. P-wave is the sharp up and down movement, called the primary wave. S-wave is the longer lasting side to side movement, called secondary waves. then there are the after shocks. PBS NOVA has several well made documentaries about that stuff.
118363
There have been different studies as to the prediction of earthquakes.  Many people have ideas such as measuring the movement of the Earth.  I have even seen a report of a man that said he could predict earthquakes using a glass pop bottle many years ago.  Having spent half my life in earthquake country the one method that aways holds true is dogs will start barking for absolutely no reason for about 15 minutes before an earthquake.