A 3.7 magnitude earthquake shook San Francisco awake this morning, with some residents saying the sudden push felt like something slammed into their home.
A quick jolt of inertia — the impulsive launch that leaves one thinking they either suffered a neurological event or the ground briefly moved beneath them — rattled San Francisco on Friday, January 10th. The United States Geological Survey (USGS) recorded a 3.7-magnitude tremor just after 7 a.m. about three miles off the coast of Ocean Beach near the San Francisco Zoo.
The burst of energy was most recognized along the western, beachside neighborhoods of the Outer Sunset and Outer Richmond; some residents took to social media saying that it felt like a large object hit their apartment buildings, producing no lingering shakes; others in downtown neighborhoods like Nob Hill and Pacific Heights described the earthquake as almost undetectable.
Quakes of this magnitude, while perceivable — USGS’s Did You Feel It? map of the event shows “weak” to “light” vibrations were felt throughout San Francisco and most of the Bay Area, even as far down as Santa Cruz — they produced little if any damage. (Any damage done by these comparably small tremors is historically minor, affecting mostly structures already in severe dilapidation.) Noteworthy deterioration to buildings and other manmade structures generally occurs with quakes north of 5.5 magnitudes in strength — earthquakes about 100 times stronger than the one registered in San Francisco this morning.
So, yes: The strength of Friday’s earthquake is nothing to headline. Several hundred similar earthquakes occur up and down California each calendar year. But what is particularly interesting about this tremor, which is already aptly called the “San Francisco Zoo Earthquake” for its proximity to the wildlife park, is how close to SF it was to the epicenter. Striking just five kilometers, or about three miles (give or take), northwest of the SF Zoo, the quake is among just a handful of 3.5-plus magnitude earthquakes to have its epicenter so close to the city.
A search through earthquake tracking reports shows this morning’s tremor was the closest 3.0-plus magnitude quake to have its epicenter near San Francisco in at least two years. Larger earthquakes have struck the Bay Area during that time frame, but none have recorded epicenters so close to San Francisco. Coincidentally enough, Friday’s 3.7 magnitude earthquake had its epicenter less than a mile from the one recorded for the infamous 7.9 earthquakes in 1906 that efficiently leveled SF; the two quakes also shared a near identical depth of about 5 miles.
With Southern California on fire, this morning’s quick rattle was additional, unescarry fuel to flame our dystopian anxieties. We’re still overdue for the next “big one,” after all.
