Impact Crater Linked To Powerful Martian Tsunamis

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    Scientists have located an impact crater linked to powerful tsunamis that cleared across part of ancient Mars. The team believes an asteroid triggered 150m-high waves when it plunged into an ocean thought to have existed on northern Mars around three billion years ago. Lomonosov crater in the planet’s northern plains fits the bill as the source of tsunami deposits identified on the surface. In-depth information was outlined at the 48th Lunar and Planetary Science Conference. In recent years, some scientists think an ocean might once have filled the vast lowland region that occupies the Red Planet’s northerly latitudes, although the idea has lost some of its currency.

    Growing evidence that tsunami waves washed over the boundary between the southern highlands and northern lowlands help strengthen the hypothesis. Steve Clifford, François Costard and colleagues identified and mapped the distribution of sediment that apparently originated in the northern plains and flowed onto a possible ancient shoreline to the south.

    Climbing High

    One type of characteristic seen on the dichotomy boundary is a lobate flow deposit. Dr. Clifford, from the Lunar and Planetary Institute in Houston, explained the evidence. He said, “These lobate deposits propagate uphill from the northern plains and do so in close association with a potential palaeo-shoreline. The predictions of the numerical modeling that François and his colleagues have done provide a very persuasive case for an ocean at this time.” He further added, “There’s also a second set of landforms that we see along the coastline called thumbprint terrain, the reflection of the tsunami waves from the coast and their interaction with a second set off tsunami waves, anticipated by the numerical modelling, would have resulted in sediment deposition that’s very similar to what we actually observe on Mars.”

    This terrain has previously been interpreted as having been caused by glaciers, mud flows and mud volcanoes. The proposed Martian tsunami traveled 150 km inland, climbing to elevations of about 100 m.

    Two Waves

    The researchers have recognized what they think is the best candidate for the impact crater, a 120km-wide bowl called Lomonosov, after the 18th Century Russian polymath Mikhail Vasilyevich Lomonosov. The feature is highly degraded today, with a collapsed crater rim. François Costard said, Two successive waves were formed during the event. This gigantic wave washed over plateaus and hills and through valleys, leaving behind the lobate flow deposits. If there was an ocean on Mars three billion years ago, it could have made the Red Planet a more hospitable place for life, raising hopes that signs of biology could be detected today.