An earthquake of a magnitude of 3.7 struck close to Millbrae, California, and the busy San Francisco International Airport on October 27, 2023, shaking the otherwise calm Bay Area. A more considerable 13.1 kilometers was the revised epicenter depth, based on expert study, after it was initially estimated to have happened at a depth of 9 kilometers.
Fortunately, the immediate aftermath brought a sense of relief, with no reports of damage or injuries. However, the incident was a stark reminder of the ever-present seismic vulnerability that looms over the Bay Area. This event was closely preceded by a string of relatively modest earthquakes that had recently shaken Northern California. On October 18, Isleton experienced a 4.1 magnitude earthquake, followed by a smaller 2.9 magnitude tremor near Twitchell Island just a few days prior. It is crucial to highlight that scientists have not yet drawn any conclusive connections between weather patterns and seismic events in this area.
Notwithstanding, the San Francisco earthquake was a powerful wake-up call, highlighting the continued necessity of alertness and continual attention in an area known for its erratic seismic activity. Note that the magnitude of the earthquake was originally reported to have been 4.0, but it was later downgraded to 3.7 by an evaluation. It was determined that the epicenter was 8.2 miles below the surface of the San Francisco International Airport.
Despite the shockwaves reaching San Francisco and Oakland, no significant damages were reported at SFO. The airport swiftly conducted runway inspections to ensure safety and normal operations resumed. The earthquake caused a brief suspension of BART service, although it was eventually restored after a brief 20-minute wait.
The minor earthquake that occurred was felt beyond its epicenter, reaching as far north as Santa Rosa and as far south as Santa Cruz. This suggests that its impact was greater than expected. BART reduced speeds as a precaution for safety inspections, which, while necessary, did cause some delays for commuters. An aftershock with a magnitude of 2.2 was reported later, serving as a reminder of the region’s seismic activity.
With a depth of about 8 miles and striking at 6:38 p.m., this preliminary earthquake affected an extensive area, from Santa Rosa in the north to Santa Cruz in the south, and even eastward to Tracy. Although the tremor caused dishes to rattle in San Francisco’s Nob Hill neighborhood, there were no injuries or significant damages reported. The temporary disruptions to BART service were a minor inconvenience, with delays of up to 20 minutes.
Adding to the seismic activity on that day, another earthquake, measuring 2.9 in magnitude, struck near Alum Rock in San Jose. Notably, San Francisco International Airport remained resilient, reporting no damage to its runways. BART acted swiftly by reducing speeds for track safety inspections. However, some social media users noted that they did not receive ShakeAlerts on their devices, as the earthquakes fell below the minimum magnitude threshold for alerting.
San Francisco International Airport faces a heightened earthquake risk owing to its proximity to the formidable San Andreas Fault. Seismologists have conducted rigorous assessments, revealing a disquieting statistical reality: there exists a 72% probability of a substantial earthquake, measuring at least 6.7 on the Richter scale, striking the San Francisco vicinity within the next three decades. The recent 3.7 magnitude earthquake beneath the airport, while minor, prompted safety inspections and transient travel delays. The airport’s control tower, equipped with cutting-edge seismic designs, meets all FAA criteria for extreme earthquakes.