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The Big One was an earthquake that was centered near the center of San Francisco, California, on April 18, 2037. The quake struck at lunchtime, lasting for 8 minutes 14 seconds, causing the deaths of at least 2550 people in San Francisco alone. The earthquake was a magnitude 9.3, making it the second strongest earthquake on record globally, behind the 1960 Chile earthquake, which was of magnitude 9.5. The megathrust earthquake had its focus 9 miles deep, and the earthquake and its immediate aftershocks caused at least 4 tsunamis over the coming hours in the San Francisco Bay, as the floor of the Bay area was repeatedly thrown up and down by the violent motions of the shockwaves, rising as much as 4 meters in some areas, before slumping by 3 meters again soon afterwards. After The Big One, 12455 aftershocks occurred, of which 27 were recorded to be above magnitude 7 over the next 2 years, adding to the devastation in the process of the immediate aftermath of the main shockwave.


Forecasts

In February 2035, the USGS reported than San Francisco was 20% likely to get an earthquake of at last magnitude 8 within 5 years, with an imminent chance of having one within the next 30 years, along the northern Hayward Fault, with a very likely likelihood of a tsunami occurring as a result of the anticipated earthquake.

As large foreshocks began with a 7.1 shock on March 15, the likelihood of a very high magnitude earthquake was steadily increasing, as radioactive emissions from the northern Hayward Fault were no high enough to be able to relieve the still increasing pressures, and the USGS revised their forecasts to say that a magnitude 8.5+ earthquake was likely to occur within the next 3 months in the San Francisco area.

After an 8.3 foreshock on March 29 6 miles to the east of the city, the fault suddenly fell silent, tough the pressure was slightly released along teh fault, possibly reducing the magnitude of the man shockwave when it arrived.

The Big One

At 1220 PDT, a minor 6.7 foreshock was recorded 3 miles from the center of San Francisco, which added to the damage already done in the area by previous shocks. At 1255 PDT, the main shockwave, a magnitude 9.3, hit 0.3 miles form the center of the city of San Francisco, wreaking havoc on the lunchtime crowds. The earthquake lasted for an unbelievable 8 minutes, 14 seconds, damaging earthquake resistant buildings, and toppling those that were not earthquake proofed since the 1989 shockwave. Huge fissures were found to have opened up in the ground, causing earthquake resistant buildings to collapse in the most extreme cases, and San Francisco sank by 3 meters as a result of the violent tremors and ground movements. San Francisco Bay rose by 1.5 meters, causing a 6 meter tsunami to hit he Bay shores within 12 minutes, killing 1700 people as it did so. Minutes later, a magnitude 9 aftershock was recorded directly beneath the Bay, pouring more water directly into the newly created faults made by the earthquake and its aftershocks, which eventually made the Bay sink below its average level. The second tsunami was 2.5 meters high, and 500 more people were killed in the process, adding even more pressure to the Hayward fault line, causing it to slip again with a magnitude 8.4 aftershock, causing the North American Plate to finally slip 12 meters to the northwest, and finally relieving the worst of the pressures on the fault, quieting it so that the bodies could be found

Aftershocks

Over the next 2 years, 12441 more aftershocks were recorded, of which 25 were recorded as being above magnitude 7. On April 29, at 0429 PDT, a magnitude 8.2 aftershock occurred under the San Francisco Bay, causing yet another tsunami, this one 4 meters high, to wash ashore on the Bay shores, which managed to rip up part of the BART rail system damaged by the earthquakes already recorded in the area, which closed the system due to health and safety risks posed by the situation.

On June 9, an aftershock clocked at 8.6 struck the Pacific Coast, which was found to be directly related to the main shock on April 18, this time causing a cross-Pacific tsunami, which hit numerous countries bordering the Pacific Ocean. The following day, a magnitude 7.9 aftershock hit San Francisco directly, virtually destroying everything that remained standing in the city, which lasted for 12 minutes at a depth of just 5 miles, causing buildings to sink as what remained of the undamaged land sank into the fissures opened up by the earthquakes. Less than an hour later, a magnitude 7.1 shock hit just 2 miles to the southeast of the center of the city, which caused many of the newly created faults in the area to slip violently.

For the next 6 months, magnitude 6 to 7.5 earthquake aftershocks were common, with the total land movement combined from all the foreshocks, the main shock and the aftershocks reaching 157 meters, the highest ever documented following a series of earthquakes.

Aftermath

In the aftermath of The Big One, the entire population of San Francisco was evacuated from the area, as the whole city was destroyed. Broken gas pipes led to a 10 day fire in the city, which was spread by further violent aftershocks dislodging the plates, which raged until a wildfire relief helicopter crew arrived to get it under control. No water pipes survived the earthquakes, and so it took 6 days of waiting until the crews could get the inferno to extinguish.

Tsunami flooding also had to be drained before any work could begin, as oil from the fault was set alight on top of the water, which was 2 meters deep in some places. As a safety precaution, the newer faults created by the main tremor were drained of water, so that the remaining aftershocks in the area would be low enough for builders to be able to work. In fact, this method proved more effective, reducing the magnitudes 85% of the remainder of the shocks by 50%.

Recovery

Return of population

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