What Causes Moonquakes? Four Ways the Moon Can Shake

How do we know the Moon has earthquakes of its own?

Astronauts on Apollo missions placed seismometers on the lunar surface. Those instruments recorded vibrations that revealed activity within and at the surface of the Moon. Modern images from NASA's Lunar Reconnaissance Orbiter provide another clue: small cliffs and fault scarps show where parts of the crust have moved.

A seismometer does not photograph a fault moving. It records ground motion. Researchers combine seismic signals, geological mapping, and models to work out what produced the shaking.

Four types of lunar shaking

1. Deep moonquakes: Earth's tidal pull

Earth's gravity does more than hold the Moon in orbit. It exerts slightly different forces across the Moon's body, repeatedly deforming it. Deep moonquakes occur hundreds of kilometers beneath the surface and are associated with these tidal stresses. This is the solid-Moon counterpart of a tidal force, not an ocean tide.

2. Shallow tectonic moonquakes: a cooling world

The Moon has been losing internal heat over geological time. As it cools, its interior contracts slightly. The outer rocky shell must accommodate that change, and stress can build along faults. When rocks slip, they generate seismic waves. NASA describes relatively shallow quakes that may be strong enough to matter for future infrastructure.

The Moon is not shrinking rapidly before our eyes. NASA estimates a reduction in diameter of roughly 50 meters over the last several hundred million years—geologically meaningful but imperceptible in everyday life.

3. Impact-generated moonquakes

The Moon lacks Earth's thick atmosphere, so many incoming meteoroids reach the ground. An impact transfers energy into the crust, creating vibrations that instruments can detect. The seismic signal from an impact differs from one produced by a fault, but both make the surface shake.

4. Thermal moonquakes

The lunar surface experiences large temperature swings between daylight and night. Rock expands when heated and contracts when cooled. Repeated changes can create tiny fractures and shallow vibrations. These events show that not every quake requires deep internal activity.

Why can lunar vibrations last so long?

Some moonquake signals reverberate for unusually long periods. One explanation is that the Moon's dry, highly fractured rock transmits and scatters seismic energy differently from Earth's wetter, more geologically active crust. The phrase 'the Moon rings like a bell' is memorable, but it should not be interpreted as meaning the Moon is hollow.

Are moonquakes dangerous for astronauts?

Future habitats, landing pads, and long-lived scientific instruments need to account for lunar shaking and local ground conditions. A fault scarp or steep slope could pose additional concerns if shaking dislodges loose material. Scientists study the distribution of quakes and faults to help assess those risks; no single map can promise that an area is earthquake-free.

Related FactLomia reading: why the Moon has almost no atmosphere, why eclipses do not happen every month, and why the Moon has phases.

Frequently asked questions

Does the Moon have tectonic plates like Earth?

No. Lunar faults and contraction-related quakes do not imply a system of moving global plates like Earth's.

Can moonquakes be caused by meteors?

Yes. Meteoroid impacts produce seismic waves that instruments can detect.

Is the Moon still shrinking?

NASA's mapping of relatively young fault scarps supports the conclusion that contraction-related tectonic activity has occurred in the geologically recent past and may continue.

The takeaway

Moonquakes are a family of events, not one phenomenon. Tidal stress, cooling-related faults, impacts, and temperature changes all contribute to the Moon's surprisingly active seismic story.