Lunar Seismic Activity Linked to Underground Salt Deposits
Moonquakes are caused because the Moon's surface is shrinking like a grape due to cooling of an ocean of molten rock beneath its surface.
In 1969, during the Apollo missions, seismometers were placed on the lunar surface, leading to the groundbreaking discovery that the Moon experiences seismic activity similar to earthquakes on Earth. These moonquakes can be categorized into four distinct types:
- Deep Quakes: These originate more than a kilometer below the lunar surface.
- Shallow Quakes: Minor shakes occurring less than a kilometer below the surface.
- Meteorite Strikes: Vibrations caused by impacts from meteorites.
- Thermal Quakes: Resulting from temperature changes on the lunar surface.
Cooling and Contraction of the Moon
One of the most intriguing aspects of these seismic activities is their potential link to the cooling and contraction of the Moon over billions of years. As it cools, the Moon shrinks in a manner similar to how a grape wrinkles up as it dries out to become a raisin. NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft has provided evidence supporting this phenomenon.
Thousands of slender tectonic cliffs have been identified on the lunar surface, indicating that the Moon has contracted globally by about 150 feet over several billion years. These tectonic cliffs are called thrust faults and resemble stair-step-like formations where one section of the crust is pushed up over an adjacent part.
Ongoing Geological Processes
Scientists believe that this process is ongoing and contributes to lunar shaking. But what drives this cooling mechanism? Beneath the Moon’s powdery outer shell lies a rigid rocky mantle and core composed primarily of minerals. Some studies also suggest an immense ocean filled with melted rock exists beneath this outer layer.
Over time, as the residual liquid within this subterranean ocean started crystallizing, element separation occurred, leading to heat release. This gradual release of heat flux has been linked to rumbling shivers through the Moon’s crust, resulting in quakes.
Implications for Future Exploration
Understanding these geological structures will be vital for deciphering planetary evolution in future exploration missions. The study of moonquakes provides insights into our natural satellite’s past and helps us prepare for future manned missions by understanding potential hazards and structural changes on its surface.
By continuing to explore and analyze these seismic activities, scientists hope to unlock further secrets about our planet’s history and other celestial bodies in our solar system.