A seismograph has two basic parts; an outer case that moves with the undulations of the earth, and an inner core that remains stable and records the earth's movements. Some seismographs are manual, but most now record the data electromagnetically.Know More
A seismograph is made up of a supporting structure, and a free mass, or seismometer, inside the device. The supporting structure is securely mounted to the surface of the Earth.
When the ground moves during an earthquake, the structure moves as well. The seismometer is suspended inside the structure, and it does not move with the outer structure. This is what allows the seismometer to record the strength and undulations of the earth during the earthquake.
It was common for the seismometer to be a type of pendulum, with a type of recording stylus on the end. The pendulum would move with the movement of the earth, and the stylus would record the movement onto a revolving drum. Most people are familiar with the long sheets of paper that had zig-zag lines running across it. Those lines are from the stylus marking the movement.
Modern seismographs have been improved from manual to being an electromagnet. The seismometer, rather than being a stylus, is a large magnet. The support structure of the seismograph is wrapped with coils of wire, turning the device into an electromagnet. The movement of the earth creates small electric signals, which are recorded and then transferred to a computer.Learn more about Earthquakes
The Chinese seismograph was an instrument developed in 132 A.D. by the Chinese philosopher Chang Hêng to detect earthquakes and determine the direction from which they came. It was a brass instrument decorated with eight dragons, each holding a copper ball. On the base were eight frogs, each with their mouth open, to catch the ball when it drops.Full Answer >
John Milne was given credit for creating the modern seismograph in 1880. His invention of the horizontal pendulum seismograph has been improved throughout the years, but the main concept is still being used today.Full Answer >
Earthquakes change the Earth by affecting and destroying landscapes, structures and environments, which threatens the inhabitants of an area and the area's entire geology. An earthquake in one place can cause a series of events that resonate out and change entire environments that are nowhere near the site of the actual earthquake.Full Answer >
Seismic testing utilizes sound waves and sensors to create a three-dimensional map of an underground area to determine what kinds of mineral resources are available. Vibrations are created using special trucks or detonated explosives. Sensors receive the vibrations and take measurements. This data is fed into complex computer programs that create maps of the area, and geologists interpret the maps to discover what minerals lie beneath the surface.Full Answer >