The familiar squeak of basketball shoes on the court, a sound synonymous with the game, has long been a minor mystery to physicists. Now, research led by Harvard University’s Katia Bertoldi is revealing that this seemingly simple sound shares surprising similarities with the powerful forces at play during earthquakes. The study, published this week, details how high-speed imaging is unlocking the secrets behind the friction that creates the squeak, and potentially offering new avenues for understanding seismic activity.
Bertoldi, the William and Ami Kuan Danoff Professor of Applied Mechanics at Harvard’s John A. Paulson School of Engineering and Applied Sciences, spearheaded a team that used advanced imaging technology to meticulously track the process behind the sound. Their findings, published on March 10, 2026, demonstrate that the squeak isn’t merely the result of shoe-to-floor contact, but rather the creation of seismic-like movements on the surface.
“For years, the squeak has been a bit of an enigma,” explains Bertoldi. “We wanted to understand the physics behind it, and what we discovered was quite remarkable. The movements happening at the microscopic level between the shoe and the floor are analogous to the ruptures that occur along fault lines during an earthquake.”
The research team employed high-speed cameras capable of capturing thousands of frames per second, focusing on a basketball shoe moving across a glass plate. The footage revealed that the rubber sole doesn’t simply glide across the surface; it undergoes microscopic “bursts” as it moves. The speed and frequency of these bursts are directly linked to the hardness and thickness of the shoe’s sole, creating a specific frequency – the squeak we hear.
Interestingly, the study found that a smooth rubber sole would produce a duller sound. The distinct, musical squeak relies on the irregularities of the rubber, which cause the bursts to be more consistent and focused, generating a clear tone. Essentially, the design of the shoe’s tread acts as an architect of the sound.
But the most striking revelation came from the comparison to earthquake mechanics. Bertoldi’s team found that the way the squeak propagates mirrors the way ruptures spread along fault lines in the Earth’s crust. The movements of the shoe sole were described as “opening-sliding bursts,” mirroring the physical principles at play during seismic events. This connection has sparked interest not only within the sports science community but also among seismologists and geologists.
“Understanding the dynamics of friction at this little scale could provide valuable insights into the much larger and more complex processes happening within the Earth,” Bertoldi stated. “By studying the seemingly simple squeak of a basketball shoe, we may be able to gain a better understanding of how energy accumulates and releases during earthquakes.”
The implications of this research extend far beyond the basketball court. Scientists believe that a deeper understanding of surface friction could lead to advancements in various fields, from industrial design to geological prediction. Controlling the effect of surface textures on friction could revolutionize the development of safer braking systems and more durable machine parts. The research suggests that by manipulating the design of surfaces, we could potentially control and even harness the power of friction.
This isn’t the first time Bertoldi’s work has garnered attention. Her research on the non-linear behavior of materials and structures has been widely cited, with over 11,000 citations as of June 2020, and highlighted by news sources like the BBC. Her work consistently pushes the boundaries of materials science and solid mechanics, exploring innovative ways to design materials with unique properties.
The discovery highlights the often-unexpected connections between seemingly disparate fields of study. What began as an investigation into a common sports sound has opened a new window into the fundamental forces that shape our world. The familiar squeak of basketball shoes, once simply part of the game, has now become a valuable tool for scientific exploration, offering a unique perspective on the dynamics of friction and the mysteries of earthquakes.
Researchers are now exploring how to further manipulate the surface textures of materials to control friction and generate specific sounds. This could lead to the development of new technologies with applications in a wide range of industries. The seemingly simple act of a basketball player moving across a court has, unexpectedly, provided a new pathway for scientific discovery.
The next step for Bertoldi and her team is to explore the application of these findings to larger-scale systems, potentially developing models that can predict earthquake behavior with greater accuracy. The team is also investigating the potential for using similar principles to design materials with enhanced frictional properties for various engineering applications.
What do you think about this surprising connection between basketball and geology? Share your thoughts in the comments below!
