In the quest to unravel the intricate mechanics of earthquakes, a team of MIT geologists has made a groundbreaking stride by decoding the precise energy distribution during seismic events simulated under laboratory conditions. Their pioneering work delves deeply into the partitioning of energy released by earthquakes, revealing a complex interplay between heat generation, ground shaking, and rock fracturing. This research not only challenges conventional perceptions of how earthquake energy is expended but may also reshape how scientists anticipate seismic hazards and the long-term evolution of fault zones.
Earthquakes, the violent shuddering of the Earth’s crust, manifest as sudden releases of stored tectonic energy accumulated over millions of years. Traditionally, much attention has focused on the seismic waves radiating from fault slippage—the very ground shaking that humans feel and measure with seismometers globally. However, these vibrations represent only a fragment of a quake’s full energy budget. The remaining energy, which dissipates as frictional heating and the creation of new rock surfaces as underground materials fracture and break apart, remains largely hidden from direct observation in natural settings.
To overcome the formidable challenges of measuring these concealed energy components in situ, the MIT researchers turned to controlled laboratory experiments to generate “lab quakes.” These miniature seismic analogs emulate the fundamental physical processes of real earthquakes but on a much smaller scale and under carefully monitored conditions. By reconstructing the fault environment in the lab with high-fidelity materials and measurement techniques, the team unlocked the capacity to dissect, with unprecedented precision, the fate of energy during a seismic event.
Central to their approach was the utilization of powdered granite, a rock representative of those found within the seismogenic zones generally positioned between 10 to 20 kilometers beneath Earth’s surface, where natural earthquakes predominantly occur. They cleverly embedded magnetic particles within this granite powder, which served as microscopic thermometers. These particles’ magnetic orientations shift predictably with temperature changes, allowing the researchers to detect transient thermal spikes generated during the simulated quakes.
In a meticulously designed experimental setup, these samples were confined and subjected to steadily increasing pressure using pistons inside a gold jacket, mimicking subterranean stress conditions. Simultaneously, piezoelectric sensors monitored the mechanical vibrations picking up the tiniest “microshakes” associated with fault slips. As the stress crossed critical thresholds, the samples suddenly slipped, emulating a seismic rupture, while the researchers captured accompanying heat signatures and fracturing evidence by subsequent microscopic imaging.
Their analyses illuminated a startling revelation: a staggering eighty percent of the quake’s total energy converts into heat during fault movement, with only about ten percent radiating as mechanical shaking that can propagate as seismic waves. Even more striking, less than one percent of the energy fosters the fracturing and fragmentation of rock material, contradicting popular assumptions that fracturing accounts for a significant portion of quake energy. These findings vividly illustrate that the lion’s share of seismic energy is sequestered in intense, transient thermal pulses localized near the fault.
Intriguingly, some laboratory samples experienced temperature spikes soaring as high as 1,200 degrees Celsius within mere microseconds upon slippage, sufficient to melt portions of the rock and transiently transform it into molten glass. This intense, ephemeral melting likely occurs in natural earthquakes as well, fundamentally altering fault mechanics by lubricating the slip zone and potentially influencing the speed and duration of rupture propagation. In one instance, sliding reached velocities approaching ten meters per second over a distance of 100 microns—a swift, albeit fleeting, motion exhibiting the rapid dynamics involved even at micro scales.
Beyond the sheer energetics, the team uncovered that the “memory” of a fault—the accumulated deformation history that alters rock properties through previous tectonic activity—profoundly sways the partitioning of energy within subsequent earthquake events. Rocks extensively disturbed in the past can behave markedly differently when slipping anew, potentially changing the relative amounts of energy diverted into heat, seismic waves, or fracturing. This dependency elucidates why similar earthquakes in distinct regions may yield differing degrees of shaking and underground damage.
The implications of these new insights extend far into the domain of earthquake forecasting and hazard assessment. By better understanding how energy is distributed beneath the surface, seismologists could refine their models to estimate the unseen effects of historic and future quakes. For example, if the energy previously imparted into heating and fracturing could be inferred indirectly, it may indicate how a fault’s integrity has evolved over time, revealing regions more susceptible to devastating ruptures or conversely, zones where faults have been effectively “healed” or lubricated by past slip.
While natural earthquakes involve immense complexity—spanning kilometers in scale, heterogeneous rock compositions, fluids, and variable temperature and pressure conditions—the laboratory experiments embrace simplification to isolate fundamental physics. This reductionist framework paves the way for extrapolating key processes to nature, supplementing in-field observations and underpinning numerical simulations that ultimately strive to protect human communities by anticipating seismic risks more accurately.
From a technical standpoint, the integration of magnetic particle thermometry alongside piezoelectric sensing represents a methodological innovation. This dual approach captures both thermal and mechanical signals with high spatial and temporal resolution, enabling the first holistic quantification of earthquake energy budgets. Furthermore, microstructural analyses through microscopy provide tangible evidence of the minute-scale damage and melting processes, validating energy partition estimations and linking them to physical transformations within the fault materials.
This multidisciplinary study, involving close collaboration between earth scientists and physicists at MIT, Harvard University, and Utrecht University, reflects an emerging paradigm in geophysics where experimental and theoretical techniques unite. Frontiers in earthquake research increasingly depend on such integrative frameworks to bridge microscopic phenomena and tectonic-scale outcomes. The present findings represent a significant milestone, presenting one of the most comprehensive views of the physics governing earthquake ruptures within laboratory settings.
Looking ahead, the researchers aspire to expand these experiments to encompass more varied rock types, fluid-saturated conditions, and more complex stress regimes, striving to inch closer to the behavior of real-world fault zones. Combined with advances in seismological imaging and computational modeling, such efforts have the potential to revolutionize earthquake science, informing building codes, emergency preparedness, and infrastructure resilience strategies.
Supporting this research was funding from the U.S. National Science Foundation, marking a vital investment in advancing our fundamental understanding of Earth’s dynamic systems. As modern societies grapple with the devastating consequences of earthquakes worldwide, elucidating the hidden energy mechanisms driving these events is paramount.
In essence, the work by Matěj Peč, Daniel Ortega-Arroyo, and their colleagues transcends traditional seismic research by casting new light on the unseen energy flows during fault rupture. It confirms that beneath the surface, earthquakes are not merely violent ground shaking but also intense bursts of heat and material transformation, reshaping how geoscientists perceive the Earth’s seismic heartbeat.
Subject of Research: Earthquake energy budget, seismic rupture mechanics, laboratory simulations of earthquakes, heat generation during fault slip
Article Title: “’Lab-quakes’: Quantifying the complete energy budget of high-pressure laboratory failure”
Web References: http://dx.doi.org/10.1029/2025AV001683
References: Peč M., Ortega-Arroyo D., O’Ghaffari H., Cattania C., Gong Z., Fu R., Ohl M., Plümper O. (Year). “’Lab-quakes’: Quantifying the complete energy budget of high-pressure laboratory failure.” AGU Advances.
Image Credits: Courtesy of Matěj Peč, Daniel Ortega-Arroyo
Keywords
Earthquakes, Seismology, Earthquake forecasting, Geophysics, Earth sciences, Geology, Natural disasters, Plate tectonics, Geodynamics, Dynamic topography, Physical sciences, Physics, Earth tremors, Seismic tomography
