The Always Active Ring of Fire

The Ring of Fire circles the Pacific Basin in a 40,000km (25,000 mi) series of deep ocean trenches and active fault lines from New Zealand to the southern tip of South America. The trenches and fault lines occur where two tectonic plates meet. In most cases, it is an oceanic plate such as the Pacific Plate pressing into and pushing under a continental plate such as the North American or Eurasian Plate that causes trouble. This constant pressure creates the stress that from time to time causes a fault line rupture resulting in a catastrophic earthquake often followed by a tsunami.

In November, 2016, two strong earthquakes hit on the Ring of Fire. The first was a magnitude 7.8 that struck New Zealand’s South Island near Christchurch on November 14. The quake triggered a tsunami that caused little damage, but the quake itself caused massive infrastructure damage and killed two people.

One week later, on November 21, Japan had a magnitude 7.4 earthquake that occurred in the same area as the disastrous 2011 magnitude 9.0 earthquake and tsunami. Although the November 21 quake was felt as far away as Tokyo, it caused no serious damage or loss of life.

The four strongest earthquakes on record all happened on the Ring of Fire. The strongest recorded since modern record-keeping began in 1900 was the magnitude 9.5 Valdivia quake that struck along the coast of Chile on May 20, 1960. It devastated Chilean infrastructure, killed 6,000 people, triggered a 25m (82 ft) tsunami that washed away villages along the Chilean coast, started landslides in the Andes Mountains, and sent a 10.7m (35 ft) tsunami rippling out across the Pacific, hitting Hawaii, Alaska, Japan, and the Philippines 10,000km (6200 mi) away.

The second strongest ever recorded was the Great Alaska Earthquake of March 27, 1964. A magnitude 9.2, the quake resulted from a massive fault line rupture in the Aleutian Trench off the southern coast of Alaska. The Aleutian Trench marks the convergence of the Pacific and North American Plates. The tsunami wave generated by the earthquake reached a height of 67m (219 ft) in one Alaskan inlet. Several coastal villages were wiped out and had to rebuild on higher ground. 131 people died.

The Indian Ocean earthquake of December 26, 2004 was the third strongest on record, but by far the most destructive. A massive 1,000km (600 mi) rupture along the boundary between the oceanic Burma Plate and the continental India Plate triggered a magnitude 9.1 earthquake and a killer tsunami, taking 230,000 lives in 14 countries bordering the Indian Ocean. Indonesia and Thailand were especially hard hit. 15 to 30m (50 to 100 ft) tsunami waves washed far inland, catching many by surprise. The Indian Ocean had no tsunami warning system in place at the time.

On March 11, 2011, the east coast of Japan was hit by the fourth strongest quake on record, followed by a highly destructive tsunami. Waves up to 40m (133 ft) washed 10km (6 mi) inland, causing the Fukushima nuclear power plant to go into meltdown. Authorities reported 19,000 dead or missing, and 230,000 displaced due to massive infrastructure damage and radiation danger. The fault line rupture took place in the Japan Trench where the Pacific Plate meets the continental plate underlying the island of Honshu. The quake was so strong it elevated Japan’s main island of Honshu 3m (10 ft) and moved the island 2.4m (8 ft) east.

More than 10,000 earthquakes occur on the Ring of Fire each year. Most are minor quakes of magnitude 5.0 or less. We don’t know exactly where or when the next big one will strike, but it will not be a surprise if it is somewhere on the Ring of Fire.    

 

 

Action On the Ring of Fire

The Ring of Fire, the 25,000 mile (40,000km) series of ocean trenches, volcanic arcs, and colliding tectonic plates fringing the Pacific Rim, from New Zealand to Chile, has 75% of the world’s active volcanoes, and produces 90% of the world’s earthquakes.

The first two months of 2016 have seen moderate activity on the Ring of Fire. Volcanoes in Colombia, Ecuador, Nicaragua, Mexico, and Indonesia continue to erupt at low to moderate levels. The Sinabung Volcano on Sumatra keeps extruding lava, with intermittent explosions that belch ash plumes up to 14,000 ft. (4,300m).

Two major earthquakes shook different parts of the Pacific Rim during this period. A Magnitude 7.1 quake hit Southeastern Alaska at 1:30 a.m. on January 24. The epicenter was 160 mi (260km) southwest of Anchorage at a depth of more than 40 miles. The shaking was strong enough to knock out power to 10,000, start gas leaks and fires, and cause moderate damage to roads and structures near the epicenter. The 1 fatality was attributed to a heart attack. If the quake had struck at a shallower depth, the jolt would have been stronger and the damage greater. The Aleutian Arc, where the Pacific Plate slides under the North American Plate, is a highly active seismic area. The second strongest earthquake on record, the Magnitude 9.3 Great Alaska Earthquake, struck in the same area on March 27, 1964.

On February 6, 2016, at 3:27 a.m., the island of Taiwan was hit by a Magnitude 6.4 earthquake. Though not as high a magnitude as the January 24 Alaska quake, the depth at 14mi (23km) was much shallower, and the shaking much more intense. The quake was ranked Intensity VII — Very Strong– on the Mercali Intensity Scale. Also, the epicenter was close to a high-density population center, and therefore much more destructive. Most of the 117 fatalities occurred when an apartment building collapsed and trapped the people living inside. Whether building code violations were involved is under investigation.

Tectonic plates constantly collide and build fault line stress. Volcano eruptions, earthquakes, and tsunamis can and will strike anytime, anywhere along the always active Pacific Ring of Fire.

 

Our Shaking Earth

When we walk along the street, we most likely feel like we’re walking on solid ground. Actually, according to figures published by USGS, our world is constantly moving under our feet.

Figures published by the United States Geological Survey show that in the 7 days from March 31 to April 6, 2012, 240 earthquakes of magnitudes from 2.5 to 6.2 occurred around the world. 207 of those earthquakes (87%) took place somewhere on the Pacific Ring of Fire, the arc of converging tectonic plate boundaries that ring the Pacific basin, from New Zealand to Fiji, to Indonesia, to Japan, to Alaska, and down the west coast of North America to the tip of South America.

However, there are few places on earth that are completely earthquake free. 33 of those 240 earthquakes occurred in such diverse places as Oklahoma, Texas, Idaho, Virginia, Puerto Rico, the Caribbean, Algeria, Turkey, Pakistan, Tristan da Cunha, Tajikistan, Italy, Greece, and Poland.

Even if an earthquake struck somewhere near you, you may not have felt the earth move because most of the 240 quakes registered in the magnitude 2.5 to 4.0 range, many of those with epicenters deep underground.  There were two magnitude 6.0 or greater quakes in the 7-day period. One took place near New Guinea, and the other near Oaxaca, Mexico, an aftershock to the magnitude 7.4 that struck that region on March 20, 2012. A magnitude 5.8 earthquake off Japan’s main island, Honshu, was an aftershock to the 9.0 earthquake that hit that area in March, 2011, and triggered the tsunami that took 19,000 lives.

Earthquakes — large or small, shallow or deep underground– are produced by the constant pressure of the world’s oceanic tectonic plates pushing against and sliding under the world’s continental plates. This process of one plate thrusting into the other goes on day after day, year after year. Fault line tension builds higher and higher. Minor fault line slippages cause small earthquakes that serve to relieve some of the stress; but from time to time, a large fault line section undergoes a sudden release of the pent-up strain, causing a major rupture or fault line slippage that results in a destructive earthquake and in some cases, a killer tsunami.

Seismologists have been working on ways to predict the location and time of the next major fault line slippage and great earthquake, but the science has not yet been perfected. We know that devastating earthquakes will continue to strike. But we still don’t know when and where.

 

 

Mexico Earthquake on Ring of Fire

The Magnitude 7.4 earthquake that struck southern Mexico on March 20, 2012, at 12:02 p.m. local time did not cause any deaths or serious injuries, according to authorities. However, 60 homes in villages close to the epicenter collapsed and another 800 homes were badly damaged. Thousands were reported homeless. The strong shock was felt 200 miles (320km) away in Mexico City, where high rises swayed, a bridge collapsed, and people took to the streets.

The epicenter was near the Pacific Coast between Acapulco and Oaxaca, at a depth of 9.8 miles (15.8km), in a seismically active area where the Cocos Plate, a subdivision of the Pacific Plate, is thrusting under the North American Plate. Since 1973, 15 earthquakes of Magnitude 7.0 or greater have occurred within 300 miles (500km) of the epicenter, including the September, 1985, Magnitude 8.0 that killed 10,000, injured 30,000, and left 100,000 homeless.

The convergent boundary between the Cocos and North American Plates is a section of the Pacific Ring of Fire, a chain of tectonic plate boundaries that runs from New Zealand to Indonesia, to Japan, to Alaska, and down the Pacific Coast to the tip of South America. Plate slippages along this arc are constantly causing earthquakes, starting tsunamis, and fueling volcanic eruptions.