What Are Moonquakes And What Causes Them? – Earthquake vs Moonquake

Moonquakes are the vibrations that arise on the Moon’s surface, similar to earthquakes. Those moonquakes happen because of one-of-a-kind reasons.
Occasionally the Moon shrinks and cools down which causes cracks and ends in moonquakes. Alternatively, Earth’s gravity can make the Moon’s insides compress and make it of considerable size, inflicting moonquakes. Meteors also can create moonquakes when they hit the surface of the moon. This ability can make the Moon’s surface shake.

What are Moonquakes?

A moonquake is like tremors or shakes that happen on the surface of the Moon. Moonquakes are just like earthquakes. They were first discovered by Apollo astronauts. Even though moonquakes remain for an hour, they are weaker than earthquakes. Recorded moonquakes had been in general much less than 3 on the Richter scale, but the largest value that has been recorded is around 5 to 5.7.moon surface with craters


What are the types of Moonquakes?

These are four different kinds of moonquakes.

  1. Deep moonquakes occur deep inside the Moon because of the pull of Earth’s gravity.
  2. Shallow moonquakes are caused by the Moon’s surface cracking as it cools down. They are not very strong and happen near the surface.
  3. Thermal quakes are caused when the morning sunlight falls on the frozen crust on the surface after two weeks of deep-freeze lunar nights.
  4.  The fourth one is the vibration that is caused due to meteorites. They hit the surface of the Moon with the force of a kiloton or 1,000 tons of TNT, creating shock waves that travel through the Moon’s surface.
Cracks on lunar surface. Some theories suggest that the cracks are caused by contraction and expansion of the lunar surface
Cracks on lunar surface. Some theories suggest that the cracks are caused by contraction and expansion of the lunar surface

What are Moonquakes caused by?

Moonquakes are caused due to several reasons. One of them is Moon cooling. The Moon constantly gets smaller and the inside of the Moon also cools down which makes it contract, causing its surface to crack and create moonquakes.

Also read: How often does the red moon occur?
Earth’s gravity can also make the Moon’s inside squeeze and stretch, which give rise to Moonquakes. When a meteor hits the surface of the Moon it creates a lot of energy, which also causes moonquakes. It is similar to the Moon’s tidal pull on Earth’s surface.

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Contractions on the lunar surface.
Contractions on the lunar surface. Image credits: NASA

How do we detect Moonquakes?

We can distinguish moonquakes by using seismometers that are placed on the Moon’s surface during Apollo missions. Seismometers continuously record any shaking or vibrations on the Moon. when there’s a moonquake, they capture the movements. The recorded data is sent back to the Earth using radio signals or other methods including laser beams, Meteorite impacts, gravity changes, etc. Scientists on Earth study the data to learn more about the moonquake, like its strength and where it happened.

Seismometer installed by an Apollo mission
Seismometer installed by Apollo mission

How were moonquakes first discovered?

Moonquakes were first discovered when astronauts from NASA’s Apollo missions went to the Moon between 1969 and 1972. They placed seismometers on the Moon’s surface. These seismometers could feel and record any shaking or vibrations on the Moon.

Also read: How many times have humans been to the moon?

By studying these recordings, scientists can map the interior of the earth, and they can measure or locate earthquakes and other ground motions. Scientists on Earth started receiving data from them. They found out that the Moon wasn’t still as it looked. It had its quakes, which are now called “Moonquakes”.

Seismometer readings sent from lunar surface.
Seismometer readings sent from lunar surface. Image credits: NASA

How long does a Moonquake last?

Moonquakes last for ten minutes or more, while the smaller trembling continues for hours or afterward. Moonquakes last longer than earthquakes on Earth because the Moon lacks an atmosphere to moisten the seismic energy quickly. The exact duration depends on factors like the quake’s type and energy.

Moonquake Vs Earthquake – Difference Between Moonquakes and Earthquakes

  • Earthquakes occur on Earth’s crust and happen due to movements in tectonic plates. The Earth’s crust is divided into large pieces known as tectonic plates, and when these plates move, they can cause earthquakes. While Moonquakes occur on the Moon. The Moon’s surface is covered by a layer of lunar dust overlaid with a layer of solid rock.
  • Earthquakes are mainly caused by the release of stress that builds up along fault lines as tectonic plates shift. This release of stress creates seismic waves that cause the ground to shake. On the other hand, Moonquakes have several causes, including tidal forces from Earth, which cause the Moon’s crust to flex and generate stress. Impact events, such as meteorite impacts, can create seismic activity. The cooling and contraction of the Moon’s interior, lead to the formation of cracks and faults that can trigger moonquakes.
  • Earthquakes are common phenomena on Earth and can occur anywhere there are tectonic plate boundaries. The smallest recorded magnitude of the earthquake is usually less than magnitude 1.0 on the Richter scale, while the largest ever recorded that occurred in Chile on May 22, 1960, was between 9.5 and 9.6 on the Moment scale (Mw). In contrast, Moonquakes are less frequent than earthquakes on Earth, but they do occur. The smallest magnitude of moonquakes ever recorded is often less than 2,0 on the Richter scale or less than 1,0 on the Moment scale (Mw). The largest moonquakes recorded during the Apollo missions had magnitudes in the range of 4.0 to 5.5 on the Richter scale.
  • Earthquakes can cause greater damage to buildings, infrastructure, and the environment. They can also lead to loss of life and property. However, Moonquakes don’t have a direct impact on human structures or life since there is no human presence on the Moon.
Lunar surface with a crater.
Lunar surface with a crater.

Is a Moonquake worse than an Earthquake?

Earthquakes are more powerful and potentially more destructive than moonquakes on the Moon. The largest moonquakes are much weaker than the largest earthquakes. Earthquakes on Earth can vary widely in magnitude. The most powerful one can reach up to 9.0 or higher on the Richter scale. While on the other hand, moonquakes generally have a lower magnitude. They can range from about 2.0 to 5.5 on the Richter scale. So in terms of impact and potential harm, earthquakes are considered worse than moonquakes.

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