Your Thursday morning BART commute may have been disrupted for a noble cause, as the biggest earthquake drill of the year, the Great ShakeOut, is happening across California and the whole world.

BART riders may encounter a curious delay Thursday morning, but don’t worry, this is only a test of BART’s ShakeAlert system. As seen below, at 10:20 a.m. Thursday morning, “Trains will slow to 27 mph and briefly stop,” according to BART. “ We will then make a systemwide announcement encouraging riders to be prepared for earthquakes.”

It’s all part of the Great ShakeOut, a worldwide earthquake drill that happens on the third October of every year at 10:20 a.m. local time. And while it is worldwide (they’ll be sounding the tsunami sirens in parts of Washington state), earthquake preparedness is a particularly timely topic in the Bay Area, as Tuesday was the 33rd anniversary of the Loma Prieta earthquake that killed 63 people and injured roughly 3,700 more.

“Be prepared and join millions of people participating in Great ShakeOut Earthquake Drills worldwide on October 20th,” the U.S. Geological Service says in their online announcement. “During the drill, participants practice ‘Drop, Cover, and Hold On!’ and other recommended safety actions to take during an earthquake.”

So yes, this is a glorified version of the old ‘Stop, Drop, and Cover’ from our grade school days, except much larger. “More than 44.1 million people worldwide are slated to participate in the event, according to data from,” the Chronicle reports. “The USGS website shows that 9.4 million participants have registered for this year’s Great ShakeOut across California, surpassing the 7.6 million participants last year.”

So since it’s earthquake drill day, it’s a good day to remind people that you can sign up for text alerts and earthquake alert apps, some of which give as many as 20 seconds advance notice of an impending earthquake. And it is wise to have a preparedness kit or “go bag” handy, because we are likely due for a big one some day or year.

Related: San Francisco Conducts Drill to Practice Airlifting In Supplies After a Major Earthquake Takes Down Bridges [SFist]

Image: Mahmoud Sulaiman via Unsplash