The shaky grounds of earthquake science

It was 3:30am when the 2,000 residents in the quaint, historic town of Amatrice woke up to their ground beneath their feet shaking, trembling. Measuring 6.6 on the Richter scale, the earthquake has so far killed more than 260 people, with many more missing.

The quake, although deadly, is not the worst to strike in the past two decades. In 2008, a quake in Western Sichuan, China killed 80,000, and a 2004 quake off the coast of Western Sumatra, triggered multiple tsunamis in the Indian subcontinent claiming as many as 230,000 lives.

For those in need of a refresher, this National Geographic earthquake 101 video explains how tectonic plates, which cover the surface of the earth like eggshells, grind past each other along lines called faults. When the movement of these plates is blocked, stress builds up, the fault gives way and released energy moves through the earth through seismic waves.

These are either surface waves which ripple laterally across the Earth's surface, like ripples on a lake, or body waves which travel vertically from the source. It is the former that causes the most damage as it tends to uproot infrastructure horizontally by shaking foundations.

It all sounds like a simple school lesson, that is till an earthquake hits and villages collapse, cities turn to rubble and life for hundreds — if not thousands — changes forever, at times under 30 seconds.

Earthquakes tend to frequent faultlines. The ring of fire, the area that fringes the Pacific Ocean, is known for its frequent tectonic plate activity.

The science of prediction

Temblors are predicted by calculating the probabilities based on the frequency of massive earthquakes in the area in the past, studying animal behaviour and detecting radon gas emissions which usually precede an earthquake. There are some scientists who are sceptical about whether the emission of radon gas is an accurate indicator of a potential quake due to a lack of evidence.

Scientists predict the probability of quakes by looking at when they last occurred in the past 200 years, and so assign a 50% possibility to an earthquake measuring at least 7.0 on the Richter scale occurring again in the next 50 years. However, having a vague idea of when the next earthquake is going to take place does not effectively help in saving lives as the location and specific timing of when it will happen is instrumental in implementing evacuation strategies.

There are attempts to update and improve the current method of predicting earthquakes, so as to provide a more accurate idea of when they are due to happen. The most obvious issue with predicting earthquakes is that it is a complex task. There are many variables that factor into how they occur, such as minerals, pressure and temperature.

Scientists at the Delft University of Technology in the Netherlands are currently working on an algorithm that can model the movements of rocky mantle, the earth's crust. The development of this algorithm is still in its fine-tuning stage as it is difficult to compute the flow of molten lava below the crust.

The issue of being able to accurately predict earthquakes is so contentious that in 2009, five scientists and a government official were convicted of multiple manslaughter for an inaccurate forecast that there would be no temblor after tremors were felt in Italy. A 6.3 earthquake killed 309 people soon after.

Although there is a dire need for accurate methods of predicting when the next quake will hit, no existing mechanism is 100% reliable.

Sounding the alarm

One way of mitigating the damage caused by earthquakes is through early warning systems. This allows people to reach safety in the first few seconds or minutes of an earthquake, with sensors detecting the first waves and warning earthquake alert centres, which in turn inform the public.

Japan so far is the only country that has a comprehensive early warning system in place in the event of an earthquake. Mexico City, Mexico has set up an early warning system as well while people in USA also make use of an app called ShakeAlert.

Experimental phone apps such as ShakeAlert help detect earthquakes in certain parts of America by identifying any seismic waves in the early stages and delivering notifications to those in harm's way.

Another app that detects the scale of an earthquake as soon as it starts is MyShake. The app uses the velocity and ferocity by which a phone shakes when placed on a flat surface; obviously prone to errors.

However, an effective earthquake warning system must also include the setting up of seismic stations, along with GPS (Global Positioning Systems) that detects any displacement in ground positioning.

As yet it remains difficult to detect the amount of energy released when tectonic plates slip past each other and the points at which they come into contact. This means, the magnitude of earthquakes and their location may not always be predicted with 100% accuracy. Although there are areas that are commonly known as earthquake zones, it is difficult to forecast specifically where and when an earthquake may occur.

Redundant tools of the trade?

Earthquakes are usually detected by use of a seismometer, which records ground movement.

The intensity or scale of earthquakes is mostly recorded on the moment magnitude scale which replaced the Richter Scale. Both scales measure ground movement on a logarithmic scale; on the Richter, a tenfold increase in ground movement was measured as a point increase on the scale.

As explained by an article in WIRED: "In the current logarithmic earthquake scale, a whole number increase, like from 7.0 to 8.0, actually means a 32-fold increase in earthquake energy."

As is probably evident, there are issues with these antiquated formulae — the Richter scale was developed in the 1930s.

The current scale also does not take into account the potential damage done by an earthquake. An earthquake that occurs in an area with poorly built infrastructure at 6.7 on the Richter scale will experience more damage than a 6.9 earthquake on the scale in an area with earthquake resistant infrastructure.

The same WIRED article goes on to explain how new formulas not only exist but are in use by scientists outside the mainstream industry of predicting temblors.

Building better
If we cannot predict earthquakes in time or measure them accurately, then can we construct safer, quake-proof buildings?

Since earthquakes can at best be detected, the approach to minimising the damage has been through constructing safer buildings, ones that absorb the impact and collapse as minimally as possible.

The International Code Council (ICC) created the International Building Code, which provides a model of an how an ideal building should be, with earthquake hazards factored in. This code has been adopted across the United States for the most part but there are other earthquake prone zones that may not necessarily have adhered to it.

Engineers and scientists have realised that completely earthquake-proof buildings are a little out of reach for now and have instead settled for earthquake resistant buildings which use "smart" materials.

These structures may be flexible or built on a base of ball bearings, or even make use of magnetorheological (MR) fluid; in the event of active ground movement, they will be able to provide some flexibility to the structure instead of collapsing.

A Japanese company has also come up with the idea of a levitating house that offers protection during an earthquake by hovering in the event of an earthquake.

Japan also tends to prepare for earthquakes quite well, with schools conducting earthquake drills and stocking up on earthquake kits at workplaces, schools and home.

Buildings in the United States have also been engineered to absorb shock from earthquakes. An example of this is the Transamerica Pyramid in San Francisco. During the Loma Pierta earthquake that struck at 6.9 on the scale, the building swayed almost a foot from side to side, but it remained undamaged.

Taking up a different tack, some are attempting to make the ground earthquake proof by strategically boring holes, planting trees or erecting swaying musical rods.

They say "earthquakes don't kill people, buildings do," but the buildings keep on piling up, storey upon storey. Till better prediction and measurement methods are implemented, building smarter infrastructure based on each locale's topography seems to be the only way to save lives when the ground wobbles, shakes and trembles.

Author: Azaera Amza