Nothing would set off a cycle of magnetic surges, and an orchestra of volcanic activity more quickly than would a close planetary flyby. A sudden, invading gravity such as the Earth would disturb and disrupt the molecules of the magma within Mars.
The year was 747 bce. It was the 7th anniversary of the founding of Rome. This ravenous flaming wolf-star--called "Maha (great) Ares" or "M'Ares" (Mars)--savagely tore open the Earth, gouging it asunder with painful clefts and fissures. The howling rock wrenched out of place gave out an anguished wail.
The mass of Mars, although but a ninth that of the Earth, was still great enough to pull open fault lines as the sullen planet ground its way past us. The sky glowed red and black from the volcanic fire and ash above as the gravitational tides of the two planets pulled magma from each other while white-hot liquid rock burst forth into space.
Packs of dogs scavenged the dead and dying. The ruined land was overrun by rapacious hordes of marauders and madmen. The whole world fell screaming into a dark, horrific abyss of blood.
Computer projections of planetary orbits show that Mars and Mercury have been in their current orbits for no more than the last 1.5% of the history of our Solar System. Moreover, they will not stay where they now are: Projected into the future, they will eventually careen out of orbit, and they may well threaten the Earth again.
Theories of Mars destruction
Glacis the Ice Moon of Mars Demolished
The closest of all of the Mars flybys set the stage for seven events all at once. They were:
1. The shattering of Glacis,
2. The rampaging rivers of Mars,
3. The sudden rain accompanying Noah's Flood,
4. The Earth's subsequent gathering of ices from space in two ice dumps over its two magnetic polar regions,
5. The genesis of the close in, short term icy comets,
6. The cometary tail Mars once had in ancient times,
7. Monster tides in the Indian Ocean which floated the Ark of Noah into the mountainous terrain of Inner Asia.
That is a lot of achievement for one small 500 or 600-mile ice ball.
The year 2484 B.C. involved the closest flyby ever made by Mars. It was the time when Mars was 15,000 miles from the Earth conservatively. It might have been the beginning of the end for the Catastrophic Era of the Mars-Earth Wars.
Most, if not all of the Alpine Himalayan Cycle is the product of just one Mars flyby, horribly close the closest of them all at 14,500 to 15,000 miles distant. Measurement is planet center to center. (Mars has a radius of 2,100 miles and the Earth's is 3,950 miles.) Thus, when Mars was that close, the closest surfaces of the two planets would have been 14,500 minus 6,000 miles, or some 8,500 to 9,000 milcs apart.