Marsquake detected by InSight lander’s seismometer
A small tremor, or quake, in the Martian interior was detected by the Seismic Experiment for Interior Structure (SEIS), a highly-sensitive seismometer placed on the Red Planet by NASA’s InSight lander.
Unlike three previous seismic signals the instrument detected since its December 2018 placement on Mars, this one—picked up on InSight’s 128th Martian day, or Sol, on April 6, 2019—came from within the planet rather than from wind or other phenomena above the Martian surface.
InSight was sent to study Mars’ interior, which is much calmer than that of Earth’s, where weather and oceans regularly produce small tremors.
The quiet Martian subsurface enables SEIS to detect and track very small quakes that would not be noticeable on Earth, where seismic noise is a regular occurrence. While this particular tremor was not large enough to yield data about Mars’ interior, scientists are now studying the data to identify the quake’s cause.
“We’ve been waiting months for a signal like this,” said SEIS team leader Philippe Lognonne of France’s Institut de Physique du Globe de Paris (IPGP). “It’s so exciting to finally have proof that Mars is still seismically active. We’re looking forward to sharing detailed results once we’ve had a chance to analyze them.”
On Earth, quakes are typically caused by the movement of tectonic plates along faults. Mars, like the Moon, does not have plate tectonics; however, both these worlds experience quakes as a result of stress produced by regular cooling and contraction processes below their surfaces. Quakes on the Moon and Mars occur when growing stress causes their crusts to break.
Seismometers on Earth are placed and sealed in underground vaults to block surface weather and temperature changes that interfere with accurate measurement of seismic activity. Though InSight sits on the Martian surface, it is covered by a Wind and Thermal Shield that protects it from high winds and extreme temperatures.
Moonquakes were first detected during NASA’s Apollo missions. Between 1969 and 1972, astronauts placed five seismometers on the lunar surface, which picked up several thousand tremors. Because the speed and reflection of seismic waves varies based on the presence of different materials beneath the surface, scientists used moonquake data to learn the composition of the Moon’s interior and even create computer models of its formation.
“The Martian Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during the Apollo missions,” said Lori Glaze of NASA’s Planetary Science Division.
Members of the SEIS team hope to measure and detect more Marsquakes in the future.
“InSight’s first readings carry on the science that began with NASA’s Apollo missions,” said InSight principal investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory in California. “We’ve been collecting background noise up until now, but this first event officially kicks off a new field, Martian seismology!”
On a video and audio recording of the quake released by mission scientists, three different sounds can be heard—noise coming from the Martian wind, the actual quake, and movement of the lander’s robotic arm as it captured photographs of the site.
Video courtesy of JPL
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.