Extinction Theory: Is the number of earthquakes increasing?

Over the last four weeks, Earth shook more than usual as tremors ranged from 4.5 to 8 on the Richter scale


Naveed Ahmad April 22, 2016
Residents search for belongings in the rubbles of a house after it was damaged by an earthquake in Peshawar, Pakistan, October 26, 2015. PHOTO: REUTERS

Whenever an earthquake strikes in Pakistan, social media buzzes with end-time prophecies. For Pakistanis, it’s more to do with the sins people commit than the shaking of tectonic plates beneath the surface. Over the last four weeks, Earth shook more than usual as tremors ranged from 4.5 to 8 on the Richter scale. An increase in volcanic activity has also been measured. The successive high intensity jolts keep people worried whether an earthquake spree has set in.

Geologists have not come up with any convincing answer yet. The question of chain-reaction to one large earthquake has been raised before too, especially after the 2004 quake that caused massive tsunami in the Indian Ocean. Scientists have been only studying patterns in occurrences and intensity at various geological locations. Predicting earthquake has not been possible thus far.

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Earth's crust and uppermost mantle comprises seven major tectonic plates, each estimated to be as thick as 100km. They are not perfectly aligned, thus their borderlines remain stressed resulting in one sliding underneath the other or rubbing against each other causing earthquakes. Such tremors occur hundreds of times a year but those above 4.5 on Richter scale can be felt by humans while those close to 2 are recorded only by scientific equipment installed around the planet.

This USGS screen grab shows earthquakes registered over the last four weeks worldwide

A group of geologists believes the planet is still working as usual and there is no surge in earthquakes. According to them, increase in human population is responsible for greater chaos resulting from the routine movement of tectonic plates. For example, they argue, there were hardly populated areas in northern Canada or some parts of China, New Zealand or Chile which is why the geological activity went unnoticed.

The second argument is linkage of seismic centres with the Internet and news media. Despite the lack of capability to predict any forthcoming tremor, this segment of geologists foresees no end of time resulting from the movement of tectonic plates. To these calm heads, no patterns exist in earthquakes, including the ones in Japan, the Hindu Kush or somewhere in South America.

Yet, some scientists believe and prove otherwise. For example, a recent study led by Tom Parsons and Eric Geist, research geophysicists with the US Geological Survey (USGS) in Menlo Park, California, found earthquakes occurring 200 times more in the first quarter of 2014 than the average of recorded earthquakes since 1979. The year 2016 is an exception too. "We have recently experienced a period that has had one of the highest rates of great earthquakes ever recorded," Tom Parsons was quoted as saying.

Geologists are convinced that large earthquakes are linked to each other but complain they simply lack the data to understand such global ‘communication’ between tectonic plates. So far scientific evidence is largely understood to suggest that great quakes rattle the crust at random.

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According to the study by Tom Parsons and Eric Geist, the average rate of earthquakes larger than magnitude 7, which used to be 10 per year since 1979, rose to 12.5 per year starting in 1992, and now rests at 16.7 per year since 2010. The duo records the increase in occurrences at 65%. Occurrence of earthquakes has doubled since 2014, yet, scientists hesitate to conclude that giant earthquakes appear in clusters.

There is another interesting and comforting theory for panicked Pakistanis. The current surge in recurrent and large earthquakes, ranging from Indonesia to Afghanistan, will significantly reduce chances of fatally huge ones for at least the next three decades. Simply put, the ongoing seismic activity is causing release of tectonic energy with a certain consistency, disallowing unprecedented strain on the tectonic plates.

For countries on active fault lines, such as Pakistan, there is little reason to abandon earthquake preparedness. Remember, there is nothing definite about what is happening in the earth’s belly.

Naveed Ahmad is a Pakistani investigative journalist and academic with extensive reporting experience in the Middle East and North Africa. He is based in Doha and Istanbul. He tweets @naveed360

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