![]() The symbols indicate different types of seismic stations. The SCSN is also part of the California Integrated Seismic Network (CISN) that coordinates earthquake monitoring statewide. All the data are transmitted automatically to Caltech/USGS in Pasadena for processing and distribution of information such as epicenters, magnitudes, and ShakeMaps. Each station records seismic waves from both near and distant earthquakes. Larger imageThe Southern California Seismic Network (SCSN) records data from more than 370 seismic stations. Of the entire portion of the fault that moved can be calculated. Within a few more hours the shape and location Now computers determine this information automatically within minutes. This process used to take almost an hour when done manually. Knowing how fast seismic waves travel through the earth, seismologists can calculate the time when the earthquake occurred and its location by comparing the times when shaking was recorded at several stations. Scientists have used knowledge of the differences between these and other seismic waves to learn a great deal about the interior of the earth. The S-wave is slower but larger than the P-wave and does most of the damage. As the wave passes by a seismic station, that piece of ground vibrates and this vibration is recorded.Įarthquakes produce two main types of waves - the P-wave (a compressional wave), and the S-wave (a shear wave). ![]() That vibration pushes the adjoining piece of ground, causing it to vibrate, and thus the energy travels out from the earthquake in a wave. In an earthquake, the slip of a block of rock over another releases energy that makes the ground vibrate. Each seismic station in the network measures the movement of the ground at that site. Also, every region of the world has a story about earthquake weather, but the type of weather is whatever they had for their most memorable earthquake.Įarthquakes are recorded by a seismic network. People tend to notice earthquakes that fit the pattern and forget the ones that don't. Earthquakes begin many kilometers below the region affected by surface weather. In fact, no correlation with weather has been found. Rayleigh waves are slower than body waves and typically travel at a speed that is 10% slower than S-waves.Many people believe that earthquakes are more common in certain kinds of weather. Like rolling ocean waves, Rayleigh waves move both vertically and horizontally in a vertical plane pointed in the direction in which the waves are travelling.Įyewitnesses have claimed to observe Rayleigh waves in large open spaces, such as car parks, where they described the vehicles moving up and down like corks floating on the ocean. Rayleigh waves, also known as ground roll, spread through the ground as ripples, similar to rolling waves on the ocean. There are several types of surface wave, but the two most common varieties are Rayleigh waves and Love waves. Although they move even more slowly than S-waves, they can be much larger in amplitude and are often the most destructive type of seismic wave. As their name suggests, surface waves travel just below the surface of the ground. Surface waves are typically generated when the source of the earthquake is close to the Earth’s surface.
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