Every year, earthquakes cause thousands of deaths, either directly or due to the resulting tsunamis, landslides, fires, and famines. Quakes occur when a fault (where Earth's tectonic plates meet) slips, releasing energy in waves that move through the ground.
Scientists measure the strength of tremors on the Richter scale, which assigns magnitude in numbers, like 6.0 or 7.2. A 5.0 tremor is equivalent to a 32-kiloton blast, nearly the explosive power of the atomic bomb dropped on Nagasaki in 1945! Going one whole number higher -- such as from 5.0 to 6.0 -- reflects a tenfold increase in the amplitude of waves. Here are some of the most destructive earthquakes in recent history.
Pakistan: October 8, 2005
This earthquake, which registered 7.6 on the Richter scale and was felt across much of Pakistan and northern India, killed more than 80,000 people, injured almost 70,000, and destroyed thousands of structures. Landslides, rockfalls, and crumbled buildings left an estimated four million people homeless and cut off access to some areas for several days.
Indonesia: December 26, 2004
This massive earthquake just off the west coast of the island of Sumatra, and the tsunami that followed, killed at least 230,000 (and perhaps as many as 290,000) people in 12 countries -- including about 168,000 in Indonesia alone. It registered 9.1 on the Richter scale and will long be remembered for the devastating waves that brought fatalities to countries all around the Indian Ocean. Scientists say the tremor was so strong that it wobbled Earth's rotation on its axis by almost an inch.
Japan: January 17, 1995
This massive quake in Kobe, Japan, measured 6.9 on the Richter scale. It killed more than 5,000 people and caused in excess of $100 billion in property loss, making it the most costly earthquake in history. The staggering expense was largely due to the collapse of, or damage to, more than 200,000 buildings in the high cost-of-living area. Coincidentally, the Kobe quake -- or the Great Hanshin Earthquake, as it is most commonly known in Japan -- occurred on the first anniversary of the Northridge tremor.
Southern California: January 17, 1994
The 6.7 magnitude Northridge tremor left 60 people dead and caused an estimated $44 billion in damage. The rumbling damaged more than 40,000 buildings in four of California's most populated and expensive counties: Los Angeles, Orange, Ventura, and San Bernardino. The earthquake, which was felt as far away as Utah and northern Mexico, luckily struck at 4:30 a.m., when most people were not yet populating the region's crowded freeways, office buildings, and parking structures, many of which collapsed.
Central California: October 18, 1989
The Loma Prieta quake -- which struck the San Francisco area as game three of the 1989 World Series was just about to begin in Candlestick Park -- killed 63 people and caused property damage of approximately $6 billion. At 6.9 on the Richter scale, it was the strongest shake in the Bay Area since 1906. Al Michaels, an ABC announcer in the ballpark for the game, was later nominated for an Emmy for his live earthquake reports.
China: July 27, 1976
This quake, a 7.5 on the Richter scale, was one of many major tremors over the years along the "Ring of Fire," a belt of heavy seismic activity around the Pacific Ocean. It struck Tangshan, then a city of one million people near China's northeastern coast. Official Chinese figures indicate around 250,000 deaths, but other estimates are as high as 655,000.
Peru: May 31, 1970
A 7.9 magnitude quake just off the western coast of South America caused more than $500 million in damage and killed 66,000 Peruvians, with building collapses responsible for most of the deaths. Scientists say the South American tectonic plate continues to drift westward into the Pacific Ocean crustal slab, so additional serious earthquakes along the continent's coast are likely.
Alaska: March 28, 1964
The most powerful tremor in U.S. history -- lasting three minutes and measuring 9.2 on the Richter scale -- struck Prince William Sound in Alaska. Only 15 people died in the quake itself, but the resulting tsunami, which reached more than 200 feet high at Valdez inlet, killed 110 more people and caused $311 million in property damage. The city of Anchorage was hit particularly hard, with 30 downtown blocks suffering heavy damage.
Southern Chile: May 22, 1960
The strongest earthquake ever recorded -- 9.5 on the Richter scale -- was actually a succession of large quakes that struck southern Chile over the span of a few hours. A catastrophic tsunami ensued, severely ravaging the Chilean coast before rushing across the Pacific to pulverize Hawaii. In Chile, landslides, flooding, and the eruption of the Puyehue volcano less than two days later followed in the wake of the quake. All told, there were more than 5,700 deaths and $675 million in property damage in Chile, as well as Alaska, Hawaii, Japan, and the Philippines.
Southern USSR: October 5, 1948
This earthquake in Ashgabat, Turkmenistan, killed around 110,000
people, more than two-thirds of the city's population at the time. The 7.3 magnitude rumbling reduced much of the city to rubble and was one of the most devastating quakes to hit Central Asia. In 2002, the government of Turkmenistan commemorated the devastating event by issuing special coins featuring images of President Suparmurat Niyazov and his family members -- most of whom died in the 1948 quake.
San Francisco: April 18, 1906
The Great San Francisco Earthquake -- a 7.8 magnitude tremor -- brought down structures across the Bay Area. In San Francisco, buildings crumbled, water mains broke, and streetcar tracks twisted into metal waves. But the majority of the 3,000 deaths and $524 million in property damage came from the massive post-tremor fire, which spread rapidly across the city in the absence of water to quell the flames. People as far away as southern Oregon and western Nevada felt the shaking, which lasted nearly a minute.
Missouri: December 16, 1811
The New Madrid fault -- near where Missouri, Kentucky, Arkansas, and Tennessee meet -- witnessed an 8.0 or greater magnitude quake nearly 200 years ago. The shaking spread so far that church bells reportedly rang in Boston, more than 1,500 miles away! It had dramatic effects on the area's geography, lifting up land enough to make the Mississippi River appear to flow upstream. Fortunately, the sparsely populated area suffered only one death and minimal property damage.