Table of Contents
What information does a seismogram provide?
A seismogram is the recording of the ground shaking at the specific location of the instrument. On a seismogram, the HORIZONTAL axis = time (measured in seconds) and the VERTICAL axis= ground displacement (usually measured in millimeters).
What can one seismograph station determine?
One seismic station can give information about how far away the earthquake occurred, but yields little other information. The cartoonish amplified ground motions show the compressive P wave, the shearing S wave, and the rolling surface wave motions recorded by many stations with their characteristic seismograms.
What kind of information do seismic stations collect?
Earthquakes are recorded by a seismic network. Each seismic station in the network measures the movement of the ground at that site. In an earthquake, the slip of a block of rock over another releases energy that makes the ground vibrate.
Which is detected first in the seismograph?
P waves
Because P waves are the fastest seismic waves, they will usually be the first ones that your seismograph records. The next set of seismic waves on your seismogram will be the S waves. These are usually bigger than the P waves.
What is difference between P waves and S waves?
P waves are recorded earlier than S waves, because they travel at a higher velocity. P waves can travel through liquid and solids and gases, while S waves only travel through solids. Scientists use this information to help them determine the structure of Earth.
What patterns do seismograph data reveal?
Seismographs record a zig-zag trace that shows the varying amplitude of ground oscillations beneath the instrument. This record is proportional to the motion of the seismometer mass relative to the earth, but it can be mathematically converted to a record of the absolute motion of the ground.
How does a seismograph measure?
A seismogram is a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. Seismograms typically record motions in three cartesian axes (x, y, and z), with the z axis perpendicular to the Earth’s surface and the x- and y- axes parallel to the surface.
What are the parts of a seismograph?
A modern seismograph includes five basic parts: a clock, a sensor called a seismometer that measures intensity of shaking at the instrument’s location, a recorder that traces a chart, or seismogram , of the seismic arrivals, an electronic amplifier, and a data recorder that stores the information for later analysis.
Where was the earliest seismograph developed?
The earliest version of the seismograph was developed in China around the second century. Various versions of the device were developed over the following centuries, with models similar to modern incarnations appearing around the 1880s.