IFLScience reports that researchers have reexamined two anomalous signals recorded by NASA’s Viking 2 seismometer, on sols 53 and 80. They consider the sol 80 signal the stronger marsquake candidate. If that interpretation holds, it may be the earliest recorded marsquake.
The team found that both signals had waveforms similar to earthquakes recorded in California and marsquakes detected by InSight, but different from identified Viking wind noise, according to IFLScience. The sol 80 signal occurred in the early morning, about 20 minutes after the lander recorded low wind speeds.
The researchers also inferred that the sol 80 event’s location broadly overlaps a northern-plains region associated with InSight marsquakes. They say the overlap suggests a possible long-lived active region, IFLScience reports. InSight operated from 2018 to 2022 and detected more than 1,300 seismic events, according to Universe Magazine.
The Viking instrument presents a persistent complication: It was mounted on the lander’s deck and was susceptible to substantial wind noise, Universe Magazine reports. The researchers could not pinpoint the sol 80 signal’s cause. Their discussion leaves open alternatives including a distant tectonic marsquake or a meteorite impact, according to IFLScience.
