The 8.8-magnitude earthquake and tsunami that struck south central Chile a year ago killed more than 500 people and cost the country $30 billion. The country is recovering, as well as giving seismologists a more literal lesson.
The seismic waves released during the Chilean fault movement traveled around the world several times and triggered tiny earthquakes in central California.
While there is still strong concern over the possibility of another large quake affecting the region, the country took immediate action in the wake of the disaster to bring life back to normal. The Feb. 27 earthquake struck just before the start of Sebastián Piñera’s presidency. His Finance Minister, Felipe Larrain, began his job in March with an $8.4 billion reconstruction package, which according to Reuters included a “mix of sovereign debt issuance, higher royalties levied on mining companies and copper boom savings.”
The investments have paid off, as Reuters reported on Friday:
This growth also comes after the country braved the collapse of a copper-gold mine in the Atacama Desert near Copiapó in August. The world watched the rescue culminate in October with all 33 of the miners pulled to safety.
Geologists investigating last year’s seismograph records from the earthquake, the largest to strike Chile since the 9.5-magnitude earthquake in 1960, have found that surface waves are key in triggering microquakes in other parts of the world following a large event. The phenomena have rattled seismologists for some time, as the microquakes can often occur hours after the surface waves have passed.
Previous theories to explain the delay have considered the late arrival of microquakes as aftershocks or as a consequence of the redistribution of fluids in pore spaces.
“From our research, we’ve concluded the delayed triggering that occurs in the first few hours after an earthquake could be caused by multiple surface waves traveling back and forth around the Earth multiple times,” said lead author geologist Zhigang Peng of Georgia Tech in a press release from the school on Friday.
In a study first reported in the journal Geophysical Research Letters in December, Peng and his team identified the California microquakes as directly related to the seismic waves traveling across Earth’s surface following the Chilean quake. In a follow-up study now on the online version of the journal, the team reports that several of the surface waves that induced the microquakes hours later had traveled several times around the world.
IMAGE 1: Epicenter of the Feb. 27, 2010, 8.8 magnitude earthquake in Chile. (Wikimedia Commons)
IMAGE 2: Seismic waves produced by the Chile earthquake (bottom panel) and recorded in central California. Gn and Rn mark the two types of surface waves (namely the Love and Rayleigh waves) that propagate around the Earth for multiple times. The top panels show microearthquake signals in California that occur mostly when the Gn waves are large. Courtesy Zhigang Peng.