Does it take a while to average data from different sensors or is there another reason?
For example, I saw an earthquake today that was a 4.3 one minute after it happened then was downgraded to a 4.1 only 15 minutes later
In: Planetary Science
The amount of energy in a earthquake that reach a sensor depend on the distance from the earthquake. It both the location and the depth of the earthquake that matters. You determine location by diffrence in arrival time to different sensors.
The P waves travel at a speed of about 6 km (3.7 miles) per second at then surface. So after 1 minute the wave have only traveled 360 km. Sensors need to be even closer to be included because it take time to calculate and distribute the information. After 15 minutes information from more sensors can be included and analysed so a correct value can be presented.
The S waves that do more damage on the surface tralve at only 3.4km (2.1 miles) mes second.
Because of the travel time warning can be sent to location farther away from the earthquakes. What action are take depends on the magneude it will have when it reach the location. It will be safer to send what is a high magnetude from the data that has been analyses instead of to low a value.
Have you ever been sitting there doing nothing, then sudden have to do your job?
The seismometers get startled very easily.
But seriously, it takes a few minutes to get all the available data from all the sources, that tell us where the event was centered, how deep it was and how much energy was released.
For instance, the initial estimate might be 5, but then more data comes in that shows it’s shallower and closer than they thought, so it was actually a 4.6.
Most quake monitoring websites will have something to that affect that they try to get the even listed as quickly as possible, but magnitude evolves based on the incoming data.
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