Where were you when the great earthquake of April 5, 2024, struck? I was at a coffee shop in South Harlem when I felt it shake the stool I sat on and rattle the picture frames hanging on the walls. I knew it wasn’t just my coffee jitters. I saw everyone else in the shop gazing in equal bewilderment at what had just happened.

Admittedly, with a magnitude of 4.8, the earthquake was not so great. The event seemed to shake our Sidechat feeds a lot more than it shook our Friday mornings. Still, there’s something to be said for the earthquake—if not about its intensity, then about its breadth. The earthquake’s epicenter was near puny, rural Lebanon, New Jersey, where my parents live, but shockwaves rippled 50 miles east through the New York City metropolis.

We typically think of earthquakes as a problem for the West Coast, which lies on a boundary of tectonic plates. Every year, Southern California has 15 to 20 earthquakes with a magnitude of 4.0 or higher. Meanwhile, in the New York metropolitan area, only 18 quakes of a magnitude 2.8 or higher have occurred since 1737. For my fellow New Jerseyans, April 5 was our third largest earthquake, also since 1737. Even though the East Coast doesn’t have a history of earthquakes, there’s no escaping the movements of the tectonic plates. There are several fault lines located both within the Tri-State Area and New York City neighborhoods adjacent to us here at Columbia University.

The first is a familiar sight. Walking down Broadway or looking out from the bridge to the Law School, you’ll see a large valley spanning 122nd Street to 135th Street, where the 1 line extends onto a viaduct before tucking itself below ground again. This sizable valley is the result of the “125th Street fault line,” a fault line that runs, as you would guess, under 125th Street, just a few blocks from Columbia. Its diagonal route extends from the tip of Roosevelt Island through the upper boundary of Central Park, then almost directly through the University’s Manhattanville campus. Not only that, but the fault line has been suspected of causing the occasional earthquake, most recently in 2001.

On October 27, 2001, a magnitude 2.4 earthquake struck the Upper East Side, with its epicenter located almost directly on the fault line on the corner of Lexington Avenue and 102nd Street. While the tremor had a negligible impact, the Daily Mail, in an article almost exactly six years before the quake this Friday, claimed that the 125th Street fault line was “overdue” for an earthquake of magnitude 5.0 or greater. Its rationale is that the epicenter of such an earthquake originates in New York City once every 100 years, yet the last time it happened was in 1884, and the last one with a magnitude of 5.0 or greater was measured all the way back in 1737. While a 5.0 earthquake wouldn’t make headlines on the West Coast, an investigation by Curbed argues that, “Our population and buildings are packed so densely, our city infrastructure is so old, that a New York 5 could easily pack the wallop of a California 6.”

While the 125th Street Fault is the city’s largest fault line, Morningside Heights isn’t as unfavorably placed as some other New York City neighborhoods. Inwood, at the northern tip of Manhattan, is wedged between two fault lines of its own. The Harlem River Fault pierces right through Washington Heights directly south of Inwood. Another fault traces through 14th Street in Lower Manhattan. Yet another goes through Van Cortlandt Park—a familiar name for every 1 line voyager—in The Bronx.

In addition to fault lines, earthquake risk varies by borough. As a Spectrum News report points out, “Not all boroughs are created equal.” The Bronx is built on top of solid bedrock, making the borough’s infrastructure much more resistant to tremors than Queens and Brooklyn, which are on softer soil. Meanwhile, Manhattan, the upper third of the island, along with Central Park, are built on much stronger soil than the rest of the island.

In total, while New York City resides in a region of “low seismic hazard”—or low probability of substantial earthquakes—the city runs a “high seismic risk” because of its highly concentrated buildings, many of which were constructed without regard for earthquake safety. Before 1995, earthquake hazards weren’t included in the city’s building codes. Thus, while many of us slept through this week’s earthquake, we shouldn’t sleep just yet on the need to make New York City more earthquake-proof. The next time you travel up Broadway or Amsterdam Avenue and spot the vast valley separating Morningside Heights from West Harlem, remember that there’s no escaping the tectonic reality of even the occasional earthquake.