Approximately 90% of the energy of an earthquake does not do what you think it does

Earthquakes can be deadly and disastrous. But what we feel can constitute a small ribbon of the destructive energy of an earthquake, according to a new experience.

In a recent AGU Advances article, researchers describe how they created “laboratory earthquakes” or miniature versions of natural earthquakes created in a controlled laboratory. This allowed the team to derive a complete energy budget of earthquakes, a “simplified analog” of real earthquakes, they reported in the newspaper.

Surprisingly, they found that only about 10% of the energy of an earthquake causes the physical tremor that most people associate with earthquakes. Overall, between 68 and 98% of the energy takes place in the heat around the epicenter of an earthquake. Less than 1% of this energy is used to break the rock and create new areas.

“Our experiences offer an integrated approach that offers one of the most complete views of the physics of earthquake breaks in the rocks to date,” MIT L’Appeli, co-author of the study and geophysicist at MIT, Mit News. “This will provide indices on how to improve our current earthquake models and attenuation of natural risks.”

An artificial disaster

For experience, the team used granite samples to imitate the seismogenic layer, a section of the earth’s crust from which are generally coming from earthquakes. The objective was to simulate microphysical processes during an earthquake that pushes the rocky layers to slide along a flaw zone, according to the document.

They implement the granite in a thin powder and mixed it with magnetic particles, the particles serving as a temperature marker for researchers. Then, they placed the sample under regularly increased pressure conditions which reproduced the natural and pre-terrestrial conditions.

According to changes in the physical properties of miniature seismic layers, the researchers have determined the dynamics of the energy of each laboratory earthquake. They also found that the energy budget had changed according to the history of the distortion of a region, or “essentially what the rock remembers,” said Daniel Ortega-Arroyo, the main study and a graduate student at MIT News.

“This story affects a large part of the material properties in the rock, and this dictates to a certain extent the way it will slip,” he added.

Going to reality

The team believes that the physics of laboratory earthquakes closely reflect that of real earthquakes. Admittedly, the real world is much more complicated, but the experience characterizes the main physical processes in play sufficiently during seismic earthquakes, they said.

The results demonstrate a viable means of bypassing the “spatial and temporal limitations of our current seismological tools and our geological observations”, said the researchers. At the very least, the study could help to shed light on the creation of a physical model for the dynamics of earthquakes or the efforts of seismologists to choose the regions most vulnerable to earthquakes.

“We could never reproduce the complexity of the earth, so we must isolate physics of what is happening in these laboratory earthquakes,” said Peč. “We hope to understand these processes and try to extrapolate them in nature.”