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So a few weeks after landing, it deployed a seismometer on the surface of Mars. One of InSight’s goals was to find marsquakes. Since November of 2018, when it landed on Mars, the spacecraft has collected a treasure trove of data that scientists back on Earth have been using to understand the interior of Mars - from its crust through its mantle to its core. NASA’s little InSight Mars lander has been busy. Their results were recently published in Nature. Are these quakes a sign that there is something more going on under the surface of Mars? Or do they originate in a way we would expect, based on what we already know? To find out, two scientists, one from the Chinese Academy of Sciences and another from Australian National University, teamed up to try to understand the origin of marsquakes. Yet every once in a while, a marsquake rattles its surface. "While this is good news, NEOM is not off the hook," says Jónsson, "More investigations into local site conditions, as well as earthquake simulations, are needed to guide the construction of a resilient city.It would seem, then, that the interior of Mars is pretty quiet. "But the fact that both studies independently concluded that earthquake hazard decreases towards the southern end of the Gulf strengthens the results tremendously." And a recent analysis of sedimentary cores collected from the bottom of the Gulf also suggests that large quakes have historically been less frequent at its southern end. "There is uncertainty within each method, and lots of assumptions had to be made," says Jónsson. "We've found an efficient and low-cost way to gather vast quantities of data that enable us to calculate even very slow horizontal displacement along a north-south fault, without doing any fieldwork," says Li. "The rapid near-fault velocity gradient implies that the southernmost fault could be steadily sliding along without producing major earthquakes," he says.īoth methods have proven reliable, yet GPS surveys remain labor intensive and expensive. Perdomo used existing models of crustal deformation to interpret their observations.
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However, they noted a greater near-fault velocity to the south of the Gulf, which they attribute to the Earth's crust thinning, thereby creating less friction towards the Red Sea. She used more than 300 satellite images collected between 20 to create multiple 160-kilometer-long profiles of plate motion around the Gulf.īoth studies found the Arabian side of the fault has been moving steadily northwards at around five millimeters per year. "By focusing on areas where the satellite images overlap, where common signals cancel out, we could retrieve the north-south displacement," explains Li. However, InSAR imagery from polar-orbiting satellites does not capture north-south motion. Perdomo used a network of more than 40 global positioning system (GPS) stations on the ground around the Gulf and modeled the tectonic deformation from their positions in 2015, 20.Ĭonversely, Xing Li used Interferometric Synthetic Aperture Radar (InSAR) imagery, produced by satellites bouncing radar signals off the Earth's surface, to measure plate motion. "Estimating how fast elastic energy builds up gives us crucial information on how frequently, and how large, earthquakes might be," says Perdomo. By observing how reference points on the surface move over time, geophysicists can study the deformation of tectonic plates and observe how rapidly stress and strain is building around fault lines. Both students used satellite geodesy, a universal framework for measuring the precise location of points on Earth. Xing Li and Nicolás Castro-Perdomo, Jónsson's research students, led separate studies of plate motion around the Gulf of Aqaba. The impact of an earthquake of such magnitude beneath the proposed crossing would be disastrous, so it is essential that engineers understand the seismic hazard in the region. "They also want to build the King Salman road crossing across the Gulf to Sharm El Sheikh." In 1995, a 7.2 magnitude quake struck the northern Gulf. "This area is now of great interest to Saudi Arabia because they are building the future megacity of NEOM very close to the Gulf of Aqaba," says geophysicist Sigurjón Jónsson from KAUST. However, there has been little study of seismicity in the sparsely populated region around the southern part of the fault, where the Gulf of Aqaba meets the Red Sea. The Dead Sea Transform fault spans roughly 1200 kilometers from the Red Sea north to Turkey, and written records show it has produced many devastating earthquakes over the last 2,000 years.