While watching a Nova documentary about earthquakes, I could not help but notice the many parallels between the huge releases of energy by the Earth’s crust and the huge releases of rage that people experience when they suppress their negative emotions for too long. We have all witnessed somebody having a personal meltdown, and most of us have snapped to some degree at some point in our lives. The results are not pretty, and can leave those around us distraught. While keeping one’s feelings withheld for extended periods of time is a tendency that should be avoided, it serves as a fitting backdrop for a discussion on seismic activity.
As you compress a spring from its equilibrium position, its coils store what is known as potential energy. If the spring is released, this stored energy will be converted into kinetic energy and a vibration will ensue.
Imagine now that instead of a spring or elastic band, it is a less malleable substance that is being compressed, like a steel rod. Although a steel rod is much sturdier than a typical spring, it can actually be deformed ever so slightly by a large compressive force. In this compressed state, the steel rod stores potential energy also known as strain energy (energy due to deformation), and would snap back if released, just like the spring. While the rod deforms less than the spring, it actually stores more potential energy since more work was required to compress it. What this means is that a compressed rod will rebound more violently once released.
Earthquakes occur when the strain energy stored in the Earth’s crust is released over a very short duration of time. The period of time over which this crust deformation accumulates is usually a number of years. Inch by inch, adjacent sections of crust move with respect to one another. The boundaries in the Earth where such tectonic plates meet are known as fault lines. Unlike the steel rod, whose cross-section is measured in square inches, these tectonic plates are measured in square miles. A bigger cross-section is linearly related to the amount of strain energy stored for a given displacement. So, whereas a rod may store many kilojoules of energy, the amount of energy stored in a section of displaced rock may be measured in how many Hiroshima atomic bombs it is equivalent to (note that a 9.0 on the Richter scale is roughly equivalent to one thousand of them).
This massive amount of energy is only dangerous if it is released over a short period of time, as this constitutes a powerful energy release (P = E/t). All quakes are powerful, as the time of release, t, is always small. This massive power is spread over a reasonably large surface area, and this ratio describes the intensity of the seismic activity (I = P/A). Finally, the Richter scale is a logarithmic (base ten) scale that measures the intensity of the tremor. As such, an R = 7.0 is ten times greater than a 6.0, and one hundred times greater than a 5.0.
Still, it all comes back to the amount of energy that is stored, and this is directly related to the amount of relative slip across fault lines. The vast majority of earthquakes are so minor that we do not notice them (R < 3.0). They are the result of a small amount of deformation that builds up over a relatively short length of time. The mechanism for release is the same for both small and large earthquakes; the difference is that small earthquakes release their stored energy before too much accumulates.
These small earthquakes are an illustration for how we should all manage our emotions. It is healthy to vent our negative feelings every so often. When you have a bad day, it may suffice to play some sports and let off some steam. This is like a harmless 3.0 earthquake. When several bad experiences pile up over the course of a week, and you haven’t had a chance to discuss it with someone close to you, it can all come out in a minor fit on Friday night. Your spouse may not appreciate being subjected to a 5.0 on the Richter scale, but the dust will settle, and the extent of the damage will be minimal.
The real trouble occurs when strain energy builds up over months and years and is not released. Although, like large earthquakes, major emotional outbursts occur infrequently, such events are the most memorable, and the most devastating. Someone who has held onto negative emotions for years is like a ticking time bomb, and should consider psychological therapy. A good therapist can allow the strain energy to be released gradually, thereby reducing the intensity from a destructive 9.0 to a manageable 7.0.
The relationship between the Earth’s and our own pent up energy extends deeper still. Although many people believe that earthquakes are a surface phenomenon, the plate shifting that occurs takes place ten to twenty miles below the surface. Of course, when people explode, the emotional outburst also comes from a very deep place.
Those close to an emotionally suppressed individual can usually detect their pain. This is exactly what seismologists aim to do with tectonic plates. By placing precise GPS equipment in fault line regions, slight displacements can be measured, and the amount of energy stored can be accurately estimated. Unfortunately, such experts are not able to gradually and safely bring this tension to the surface as a psychologist does with a patient.
Massive amounts of energy are currently being stored in several earthquake prone areas such as the Chilean coast, the state of California, and the Pacific coast just above it. Sadly, the 2010 earthquake in Haiti only released some of the vast amount of energy stored in its nearby fault lines. While seismologists can detect how potentially devastating a forecasted earthquake may be, they cannot predict when they will occur with much confidence. Knowing the “when” would be the holy grail of seismology.
I suppose this is similar to a stressed out individual. It is often easy to detect that they are stressed, but impossible to know the moment when it will all come gushing out. Then again, someone who is ready to burst will usually be set off by a particularly intense event. Seismic activity can also be triggered by a number of things which are themselves unforeseeable.
So, the coping strategy for surviving earthquakes in the meantime is twofold. The first is to ensure that structures in cities near fault lines are designed to withstand reasonably large earthquakes. The immense death toll in Haiti was a consequence of weak structures that fell on people.
The second strategy is an emerging technology known as p-wave detection. The energy release far below the surface sends three seismic waves in two dimensions outward. First, a p-wave is sent, then an s-wave, and finally, a surface wave. The p-wave (primary wave) arrives first, as it travels at the speed of sound through rock. These waves are not damaging at all, but serve as a warning for what is to come. It is in fact the surface wave, which propagates slowest and thus arrives last, that does nearly all of the damage. In terms of sequence of events, a p-wave is to lightning what a surface wave is to thunder.
If you are very close to the initial point of energy release of a big earthquake, then notice of a p-wave would not even provide you with enough time to duck. If, however, you are tens of miles away, then a timer with the estimated number of seconds until the surface wave reaches you would begin to count down on your cell phone (if it has a GPS). These sorts of systems are currently in use in Tokyo and are being developed for North American implementation. These seconds of notice would save many lives, by allowing people, at the very least, to duck under a table.
The final analogy I will make between earthquakes and emotional outbursts is the residual effects that both can have. In December of 2004, an earthquake off the coast of Japan gave rise to a tsunami. The landfall beneath the water in the ocean caused a massive amount of water streaming in all directions including the land nearby. Although less dramatic, the emotional outbursts that occur when we withhold our feelings for too long can cause us to act irrationally and do things that we regret. A typical residual effect here is that those around us may become alienated.
If there is one thing that we can learn from earthquakes, it is that it is better to have regular 3.0 emotional releases than occasional 9.0 outbursts. One other lesson might be to avoid buying real estate near any fault lines.
Stephen Cohen earned his Bachelor’s (2004) and Master’s (2006) Degrees in Mechanical Engineering at McGill University. His thesis describes the dynamics of a space elevator, and he has published several scientific papers on the topic. He worked at MDA Space as a Structural Engineer, where he helped to design space antenna payloads to survive the rigours of space launch and the orbital environment. His enthusiasm for science and teaching as well as his passion for writing and public speaking led him to modify the direction of his career. In 2010, he began working as a Physics Professor at Vanier College. In the same year, he founded The Engineer’s Pulse (www.theengineerspulse.blogspot.com<http://www.theengineerspulse.blogspot.com>), a blog where he writes about science and engineering in a down to Earth way.