what happened when the water met red-hot metal?

You see what happened when the water met red-hot metal? Now, multiply that by a hundred billion times.
A gigantic volume of magma from the magma plume will rip the Mariana Trench in an instant. And billions of cubic meters of water will meet billions of cubic meters of magma.
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this gigantic explosion will cause a powerful hydraulic impact, directed inside our planet. Because 11 kilometers of water in the Mariana Trench is an enormous pressure at the point where the explosion will take place. And that pressure will in turn be reflected in the hydraulic impact.
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This will literally tear the planet from the inside. With such an impact, magma will behave like a gaseous substance. All volcanoes, cracks, fractures, all boundaries of lithospheric plates will burst and erupt simultaneously. The Earth will be flooded with lava flows, just as it happened on Mars.