Good News: The Recent Taiwan and New-Jersey Earthquakes Were Not Triggered by Humans!
As a theoretical physicist, I tend to consider all possibilities when presented with facts. Sometimes this tendency makes me anxious.
After watching the excellent film “Oppenheimer,” I became concerned with the possible existential risk from irresponsible bad actors, such as terrorist groups which get a hold of a nuclear bomb. It is easy to imagine scenarios where adversarial leaders would wish to create political turmoil by using the most devastating weapons that physics handed to humanity. If we ever visit habitable exoplanets, it would be interesting to take a census of the fraction of extraterrestrial civilizations that annihilated themselves through a global nuclear war, leaving behind them a scorched ground. Finding that a substantial fraction did it, would provide a sober answer to the question: “Where is everybody?”, asked in 1950 by the physicist Enrico Fermi, who also developed the first nuclear reactor at the University of Chicago and played an instrumental role in the Manhattan Project, led by J. Robert Oppenheimer.
Given this historical backdrop, I was intrigued by two facts over the course of a few days this week:
1. On April 2, 2024, at 19:58 EDT, a magnitude-7.4 earthquake struck 18 km, south-southwest of Hualien City, Hualien County, Taiwan. It was the strongest earthquake in Taiwan since 1999.
2. On April 5, 2024, at 10:23 EDT, a magnitude-4.8 earthquake struck near Whitehouse Station, New Jersey, about 72 kilometers west of New York City. It was the strongest earthquake in New Jersey since 1783 and the strongest in New York City since 1884.
Given the timing coincidence, I wondered whether any of these two events could have been triggered by humans. One can imagine bad actors detonating an explosive underground that would trigger an artificial earthquake. Could seismic data be used to differentiate between a real earthquake and an underground explosion? I immediately emailed my questions to my brilliant Harvard colleague, Professor Miaki Ishii, who specializes in seismology. Miaki replied promptly “how wonderful to hear from you,” and gave the following answers:
“Could seismic data be used to differentiate between a natural earthquake and a human-made explosion, such as an underground atomic detonation?
Yes. Ground motion data are collected worldwide, and looking at the seismic waves, we can tell if the event was an earthquake or an explosion. The data indicate that the two events you mentioned in Taiwan and New Jersey are earthquakes, i.e., motion associated with a slip on a fault rather than an explosion.
Can one easily examine the available public data from seismometers for these two events to rule out a human-made trigger?
The data are openly available online, and anyone interested in downloading them can. For example, the webpage:
https://ds.iris.edu/ds/nodes/dmc/tools/##
provides a myriad of ways for accessing seismograms from around the world.
As for detonating a small explosion to trigger an earthquake, that would be difficult to do. For one thing, the Taiwan earthquake was at a depth of about 35 kilometers, i.e., you can’t really dig that deep to put a bomb near the fault (the deepest we’ve ever managed to drill is down to 12 kilometers and that was an effort that took 13 years and the diameter of the hole is about 6 inches). One also can’t control what happens with the fault, so a bomb detonation won’t necessarily activate a fault. Magnitude-7.4 is like having 30 Hiroshima bombs, so trying to trigger this level of motion with a small detonation is like kicking a building in the hope it will collapse.
Also, Taiwan is one of the most densely monitored places in the world in terms of seismic instrumentation, and one won’t be able to hide an explosion big enough to have any effect at 35 kilometers depth. Similarly, detonation in the New York area would be detected — even though not as densely distributed, we have a good number of instruments there. For example, we could see different stages of the collapse of the World Trade Center on seismograms from nearby stations. It’s pretty difficult to hide things that put momentum into the ground from seismologists ….
Also, the timing of the two events isn’t that unusual. We have many magnitude-4 earthquakes in a day. In the last 7 days, we had 144 earthquakes that are magnitude-4.5 or larger, of which 57 are magnitude-5 or larger. Even though earthquakes don’t happen a lot in the East Coast of the U.S., the area is not unknown to them. In 1755, there was an earthquake at Cape Ann, Massachusetts, with a magnitude of around 6 and more recently in 2011, there was an earthquake in Virginia that was magnitude-5.8.”
I was delighted to read Miaki’s reply as soon as I woke up for my morning jog before sunrise. She made my day. Sometimes you do not realize how fortunate we are, until you imagine how much worse it could have been. The sun that I will see shortly is also powered by nuclear energy. But in the spirit of the naturalist Henry D. Thoreau who lived close to my home, I enjoy anything that nature brings my way and am suspicious of human-made interventions. As I will jog into the nearby snow-covered woods this morning, I will recite Thoreau’s words from his book “Walden”: “I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.”
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. His new book, titled “Interstellar”, was published in August 2023.
