How Does A Seismograph Work – An earthquake is vibrations that occur on the earth surface caused by the release of energy derived from skins earth suddenly.Energy come from different sources, as a collision crust, eruption a volcano or made by human beings as the explosion in mining.
To record vibrations an earthquake, used a instrument called a seismograph. A seismograph is combination of seismometer and seismogram. Seismometer is a extremely sensitive sensor that is able to detect propagation waves of vibration an earthquake. A seismogram is an earthquake recording sheet. Analog seismograms are sheets of paper, while digital seismograms are images that come from a computer. A seismogram is useful for calculating the strength of an earthquake. But, How Does A Seismograph Work?
Seismometer (Kinemetrics Inc)
How Does A Seismograph Work?
In this article we will explain how analog seismograms work. The working principle of a seismograph is that if a seismometer detects a vibration, the seismometer will send a signal to an amplifier to be amplified. The signal will be amplified 56,000 times from the initial signal. After that, a signal will be given to a drum recorder instrument. Inside the drum recorder there are additional electronic devices that can adjust the movement of the recorder needle, and the speed of the drum rotation. You can see the diagram block below. how seismograph works.
I will explain one example of a seismometer named SS-1 Ranger. Ranger SS-1 Seismometer is a production of the KINEMETRICS Inc. company, which is one of the sensor components for seismograph. SS-1 Seismometer Ranger works based on “moving coils” to produce electrical voltages based on electromagnetic fields.
SS-1 Ranger construction can be seen in figure below. On seismometers there are Spring Hanger Rod, Suspension Spring, Flexure, Output Coil, Mass (movable magnet), Period Extending Magnet, and Calibration Coil. Spring Hanger Rod and Spring Suspension are useful for controlling mass when used in vertical or horizontal fields. Flexure is useful as a field of adhesive for the masses. The Coil output is useful as a voltage source generator if there is vibration in the SS-1 ranger. The coil output has an Rg resistance coil generator, which is the resistance of the generator coil (coil signal) in the Ohms unit. The value of this resistance is 5000 Ohm. Mass is a permanent magnet that can move. Magnets The Existing Period is useful for extending magnetic fields to produce time settings. Calibration Coil is used for the calibration process. Calibration functions as a normal determination of the work of a tool to show the correct value at the time of measurement. This calibration coil has a resistance of 100Ohm. Rang SS-1 is a “spring-mass” instrument with electromagnetic transduction. Permanent magnets are made as seismic masses and coil output as a transducer attached to the frame or body of the seismometer. The mass is supported by two circular arches, which are located at the top and bottom which function to support the mass.
SS-1 Ranger construction
When the seismometer detects vibrations, the mass supported by the flex will move perpendicular to the coil output. As a result of movement by the mass, so that it will cause an electromagnetic field at the coil output. Because the electromagnetic appears, it produces a voltage at the coil output. The relationship between the constant speed from the mass to the output of the coil which can produce this voltage is called the Constant Generator. SS-1 Ranger has a constant generator which is 340V / ms. This mean, that if the mass moves with a distance of one meter in one second, the output of the coil will produce a voltage of 340V. But in reality, the mass only moves within ± 1 mm so that the resulting voltage is very small, starting from nanovolt – millivolt. The voltage generated by the coil output will be sent to the amplifier (red). The amplifier will increase the voltage by 56,000 times.
To be able to record earthquake events, a recorder is used. one sensor for one recorder There are three recorders used, for horizontal direction is namely East-West (EW) and North-South (NS). for vertically is namely Up-Down (UD). The amplifier will drive the drum motor recorder and the writing pen.
Each single recorder has several of the same devices, namely a drum, as well as several settings, namely, position, drum speed, and recording time. The recorder basically records earthquake activity on paper seismograms that are rotated at a certain speed using a pen that moves parallel to the drum continuously. Time The length of recording on a drum is 24 hours. This is how does a seismograph works. May be useful.