Trou au Natron in Chad resembles a ghostly face from space, formed by distinctive volcanic features. Satellite observations and research expeditions have unveiled its rich geological history.
Past volcanic eruptions and salt deposits from present-day hot springs left this distinctive “face” in northern Chad.
From above, the 1,000-meter (3,300-foot) deep volcanic pit and soda lake Trou au Natron in northern Chad has the look of a ghostly face staring back at you. An astronaut on the International Space StationThe International Space Station (ISS) is a large spacecraft in orbit around the Earth that serves as a research laboratory and spaceport for international collaboration in space exploration. It was launched in 1998 and has been continuously occupied by rotating crews of astronauts and cosmonauts from around the world since 2000. The ISS is a joint project of five space agencies: NASA (USA), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). It orbits the Earth at an altitude of approximately 400 kilometers (250 miles), and provides a unique platform for scientific research, technological development, and human space exploration.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>International Space Station captured this photograph of the distinctive feature on February 12, 2023.
The edge of the “face” is partly formed by shadows cast by the rim of a caldera—a type of volcanic crater formed after an explosive eruption or the collapse of the surface into a partially-emptied magma chamber. The “eyes” and “nose” are cinder cones—steep conical hills built around volcanic vents. The cinder cones are thought to be relatively young in geological terms, likely forming within the past few million years and possibly as recently as the past few thousand years.
Astronaut photograph, captured from the International Space Station on February 12, 2023, features the deep volcanic pit and soda lake Trou au Natron in northern Chad.
The white area around the “mouth” is a mineral crust made of a salt known as natron—a mixture of sodium carbonate, sodium bicarbonate, sodium chloride, and sodium sulfate. It forms as hot spring water pools on the surface and evaporates, and mineral-rich steam rises from the surface of the geothermally active area.
Trou au Natron lies just southeast of Tarso Toussidé, a broad volcanic feature with fumaroles and an active stratovolcano. One of several volcanic peaks in the Tibesti Mountains, it is the source of several relatively recent—though poorly documented and studied—eruptions.
The remoteness of Trou au Natron makes it difficult for scientists to access. However, analysis of rock and fossil samples collected in the 1960s indicate that Trou au Natron was filled by a glacial lake hundreds of meters deep about 14,000 years ago. An expedition led by German researcher Stefan Kröpelin reached Trou au Natron in 2015 and collected samples of fossilized aquatic algae thought to have formed some 120,000 years ago.
Satellite observations of the region have helped fill in some details. One pair of University of Cambridge researchers have pieced together a rough sequence of the region’s volcanic activity based on observations from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor on NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>NASA’s Terra satellite. They divided the activity into six phases, with the formation of Trou au Natron as one of the most recent events of geologic significance.
Astronaut photograph ISS068-E-53507 was acquired on February 12, 2023, with a Nikon D5 digital camera using a focal length of 500 millimeters. The image was provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 68 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet.
Source: SciTechDaily
