More than a million earthquakes strike somewhere in the world every year. Most are under magnitude 5.0, and normally cause little or no damage. But between 1,500 and 2,500 of those million-plus earthquakes are of magnitude 5.0 and higher. Depending on geographical location and epicenter depth, any quake over magnitude 5.0 is capable of inflicting heavy losses.
320,000 people have died in earthquakes and earthquake-generated tsunamis since the year 2000. Those statistics coupled with the UN’s projected 67% increase in world population by 2100, much of it in earthquake-prone areas, adds up to bad news.
According to a study by the U.S. Geological Survey, published on February 20, 2013, predicted population increases in this century can be expected to translate into more earthquakes with very large death tolls than ever before. The USGS researchers studied earthquakes with death tolls of more than 50,000, termed catastrophic, from 1500 A.D. to the present. Comparing those events to world population, they found that the number of catastrophic earthquakes has increased as population has grown. By statistically correlating the data, they were able to project that approximately 21 catastrophic earthquakes will occur in the 21st Century, tripling the seven that occurred in the 20th. Total deaths could more than double to approximately 3.5 million if world population grows to the UN’s projected 10.1 billion.
The study explains the increase in lethal earthquakes is not that we are having more earthquakes, it is that more people are living in seismically vulnerable buildings in the world’s earthquake zones. Many of the countries experiencing the highest ratio of population growth are located on or near the world’s most dangerous fault lines. Fast-growing population centers in the Middle East, the Caucuses, Asia, the Western Pacific, and Central and South America are especially vulnerable. People in Turkey, Iran, Iraq, the Philippines, Afghanistan, Pakistan, India, China, Indonesia, Haiti, Bolivia, and Guatemala, for example, not only live in earthquake zones, but in substandard housing that tends to collapse in major magnitude earthquakes.
Seismic building codes have been enforced for many years in California and other U.S. earthquake zone areas. Los Angeles and San Francisco, for example, will suffer far fewer casualties and less damage in a major quake than similar-size cities in developing areas where seismic codes do not exist or are not enforced.
Thomas Holzer, the lead research scientist in the USGS study, concludes, “Without a significant increase in seismic retrofitting and seismic-resistant construction in earthquake hazard zones at a global scale, the number of catastrophic earthquakes and earthquake fatalities will continue to increase and our predictions are likely to be fulfilled.”