A magnitude 3.9 earthquake temporarily grounded planes at San Francisco International Airport on Monday evening, causing long flight delays and diversions as authorities reacted to the unexpected tremor.
The ground began to shake at around 7:46 pm on March 17, with the epicenter of the quake located around 36 km northeast of San Francisco Airport in Dublin, California, at a depth of 11 km.
All flight operations at SFO were initially suspended, and while airport officials were able to announce an all-clear only a short time later, the effect of the temporary ground stop had already taken a toll on flight schedules for the rest of the evening.
The Federal Aviation Administration (FAA) issued an air traffic control advisory, warning airlines that delays for both departing and arriving flights would be expected for the rest of the evening.
The advisory stated that many flights that were inbound to San Francisco at the time of the quake were left waiting in a holding pattern above the city until they were finally given clearance to land.
“Last night’s jolt will serve as a reminder to San Franciscans that they live on a precariously balanced fault system, dominated by the infamous San Andreas fault line,” warned Dr Matthew Blackett, Associate Professor of Physical Geography and Natural Hazards at Coventry University.
“Small tremors regularly affect the city, and as such, what was seen last night should not be surprising, although it’s the biggest such tremor in some time,” Dr Blackett continued.
“Scientists are of the opinion that the San Andreas fault system is currently in a locked position, hence explaining the scarcity of larger events since the 1980s. What worries scientists and residents alike, however, is that day by day, stresses are building up along the fault system and that, ultimately, this could lead to a sudden and catastrophic release at some time in the future.”
For now, researchers don’t know whether last night’s events represent a potential “unzipping of the faultline,” but officials in California aren’t taking any chances, becoming the first state in the United States to launch an earthquake early warning system like the system that has been in place in Japan for many years.
Unveiled in 2019, the MyShake smartphone app was launched on the 30th anniversary of the deadly Loma Prieta earthquake by Governor Newsom.
Yesterday’s quake did not, however, set off the early warning system as it only alerts residents to take immediate action if a quake of magnitude 4.5 or higher.
