How are earthquakes recorded? How are earthquakes measured? How is the magnitude of an earthquake determined?

Earthquakes are recorded by a seismographic network. Each seismic station in the network measures the movement of the ground at the site. The slip of one block of rock over another in an earthquake releases energy that makes the ground vibrate. That vibration pushes the adjoining piece of ground and causes it to vibrate, and thus the energy travels out from the earthquake in a wave.

There are many different ways to measure different aspects of an earthquake. Magnitude is the most common measure of an earthquake's size. It is a measure of the size of the earthquake source and is the same number no matter where you are or what the shaking feels like. The Richter scale is an outdated method that is no longer used that measured the largest wiggle on the recording, but other magnitude scales measure different parts of the earthquake.

Intensity is a measure of the shaking and damage caused by the earthquake, and this value changes from location to location.

Learn more:

Magnitude & Intensity

UC Berkeley Seismo Lab Earthquake FAQ

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What is a Geoid? Why do they use the geoid, and where does its shape come from?

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A seismometer is the internal part of the seismograph , which may be a pendulum or a mass mounted on a spring; however, it is often used synonymously with "seismograph". Seismographs are instruments used to record the motion of the ground during an earthquake--installed in the ground throughout the world and operate as part of a seismographic...

How can I make my own seismometer?

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When was the first instrument that actually recorded an earthquake?

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What was the duration of the earthquake? Why don't you report the duration of each earthquake? How does the duration affect the magnitude?

The duration of an earthquake is related to its magnitude but not in a perfectly strict sense. There are two ways to think about the duration of an earthquake. The first is the length of time it takes for the fault to rupture and the second is the length of time shaking is felt at any given point (e.g. when someone says "I felt it shake for 10...

What are UTC and GMT (in reference to the time of an earthquake)?

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How can an earthquake have a negative magnitude?

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How do seismologists locate an earthquake?

When an earthquake occurs, one of the first questions is "where was it?" The location may tell us what fault it was on and where damage (if any) most likely occurred. Unfortunately, the earth is not transparent and we can't just see or photograph the earthquake disturbance like meteorologists can photograph clouds. When an earthquake occurs, it...

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How do you determine the magnitude for an earthquake that occurred prior to the creation of the magnitude scale?

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K2 Seismic Station
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K2 Seismic Station

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Earthquake-damaged building

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Attribution: Natural Hazards
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Attribution: Earthquake Hazards
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