Italy’s deadly earthquake is the latest in a history of destruction


Brendan Duffy, University of Melbourne; Mark Quigley, University of Melbourne, and Mike Sandiford, University of Melbourne

The Appenines region of central Italy has been struck by a deadly earthquake, with a magnitude of 6.2. The quake, which had an epicentre roughly 10km southeast of Norcia, Italy, occurred just over seven years after the 2009 L’Aquila earthquake that killed more than 300 people only 90km away.

The latest earthquake occurred at 3:36 am local time. The number of fatalities is unknown at time of writing but already exceeds 30. Buildings have collapsed in nearby Amatrice and residents are reportedly trapped in rubble.

General tectonic setting of Italy, showing seismicity over the past 10 years from the USGS catalogue.
USGS

Fracture zone

This earthquake is no surprise. Italy is prone to earthquakes; it sits above the boundary of the African and European plates. The oceanic crust of the African plate is subducting (sinking) under Italy, creating iconic natural features such as the volcano at Mount Vesuvius. These plates are converging at a rate of around 5mm each year.

Both the L’Aquila and Norcia earthquakes were located below the central Appenines, which form the mountainous spine of Italy.

The Earth’s crust under the Appenines of central and western Italy is extending; eastern central Italy is moving to the north east relative to Rome. As a result, this region experiences normal faulting: where one part of the earth subsides relative to another as the crust is stretched.

The fault systems in the central Appenines are short and structurally complex, so the earthquakes are not large by global standards, the largest almost invariably hover around magnitude 6.8 to 7.0. But because the quakes are shallow and structurally complex, and because many of the local towns and cities contain vulnerable buildings, strong shaking from these earthquakes has the potential to inflict major damage and loss of life in urban areas.

This region also seems to be particularly prone to earthquake clustering, whereby periods of relative quiet are interrupted by several strong earthquakes over weeks to decades.

A history of quakes

Both Norcia and L’Aquila feature prominently at either end of a zone of large Appenine earthquakes. This zone has produced many strong earthquakes. The latest Norcia earthquake occurred only around 90km northwest of the L’Aquila earthquake and very close to the epicentre of the 1979 Norcia earthquake, which had a magnitude of 5.9.

But the area’s earthquake history can be traced back over seven centuries. During this period, this region has been hit by at least six earthquakes that have caused very strong to severe shaking. Amatrice, so badly damaged in the most recent quake, was severely damaged in 1639. A few decades later, in 1703, roughly 10,000 people were killed in Norcia, Montereale, L’Aquila and the surrounding Appenine region in three magnitude 6.2-6.7 earthquakes.

Parts of Norcia were subsequently built upon the surface rupture created in the 1703 earthquake. Another earthquake in 1997 killed 11 people.

In this most recent event, an estimated 13,000 people would have experienced severe ground shaking, probably lasting 10-20 seconds.

The estimated damage of this latest earthquake will almost inevitably exceed US$100 million, and may top US$1 billion. Amatrice appears to be among the populated areas that were most severely affected.

What lies ahead?

The region now faces a prolonged and energetic aftershock sequence; over the first 2.5 hours following the mainshock, at least four earthquakes of around magnitude 4.5 were recorded in the region by the US Geological Survey. More than 10,000 aftershocks were recorded following the L’Aquila earthquake in 2009.

We note that within the region, there is excellent and continuously improving scientific information about the hazard. But the knowledge of the hazard has not always translated well into measures that directly reduce economic loss and fatalities in earthquakes.

Following the L’Aquila earthquake, six scientists were convicted of manslaughter for failing to inform the public adequately of the earthquake risk. Although the charges were subsequently dropped, this marked a major development in the way blame is apportioned after large natural events, particularly with regard to effective hazard communication.

Numerous vulnerable buildings remain, and the recovery process is commonly plagued by long disruptions and inadequate government funding to recover rapidly. Both the 2009 L’Aquila earthquake and this most recent quake highlight just how important it is to translate hazard assessments into improving the resilience of infrastructure to strong shaking. The focus should remain on linking science, engineering and policy, this is often the biggest challenge globally.

The Conversation

Brendan Duffy, Lecturer in Applied Geoscience, University of Melbourne; Mark Quigley, Associate professor, University of Melbourne, and Mike Sandiford, Chair of Geology & Redmond Barry Distinguished Professor, University of Melbourne

This article was originally published on The Conversation. Read the original article.

New Zealand: Christchurch Hit By Another Major Earthquake


A major earthquake has struck Christchurch, New Zealand, where a cliff has collapsed into the sea.

For more visit:
http://www.theguardian.com/world/2016/feb/14/injuries-and-cliff-collapse-after-severe-earthquake-strikes-close-to-christchurch

Experts Fear Earthquake-Ravaged Nepal May Suffer Another Huge Tremor Soon


TIME

Another major earthquake in the Himalayan Mountains may be imminent, according to new research that suggests the 7.8-magnitude quake that devastated Nepal in April failed to release all of the region’s seismic energy.

For over five centuries, seismic tension has been building beneath the Himalayas as India gradually shifts northward into the continent. In recent decades, a segment of the narrowing fault line between the Indian and Eurasian Plates became locked by friction, intensifying the buildup of energy that culminated in the April 25 earthquake.

The good news, scientists say, is that the quake, which left between 8,000 and 9,000 dead in Nepal and its border countries, could have been significantly worse. When the stress finally broke the fault, at an epicenter about 50 miles northwest of Kathmandu, the expense of energy traveled to the east, opening only the fault’s shorter eastern stretch, according to two concurrent studies published Thursday…

View original post 156 more words

10 charts that capture how Nepal is struggling to survive after the earthquake


Quartz

On April 25, Nepal was devastated by a massive earthquake measuring 7.8 on the richter scale, which killed thousands and displaced millions.

Now, the Nepalese need to rebuild what was lost—most importantly, their homes and key facilities like healthcare and education. And that is the toughest part.

According to the Nepal government, the tiny Himalayan country is staring at losses estimated at about $10 billion—nearly half of its gross domestic product of $19.2 billion.

Two organisations—Global Shelter Cluster and the REACH Initiative—surveyed about 1,680 households in the 14 districts that were worst affected by the earthquake, about their living conditions after the earthquake.

The preliminary results are staggering. Around 68% of displaced households are living in areas adjacent to their damaged  homes, where access to sanitation, education, healthcare and clean drinking water is severely curtailed.

Here are the results from the survey, which show how the citizens of one of…

View original post 653 more words

The economic damage from the Nepal earthquake is almost half of the country’s GDP


Quartz

The initial estimates of the economic damage caused by the April 25 earthquake in Nepal are in—and the numbers are staggering.

The overall damage is estimated to be at about $10 billion, according to the Nepal government—nearly half of its gross domestic product (GDP) of $19.2 billion. According to IHS Global Insights, a research firm, the estimated cost for rebuilding homes, roads and bridges alone could run up to $5 billion.

For Nepal—one of the poorest countries in the world—rebuilding its ravaged economy will be particularly difficult after it suffered years of slow growth.

Nepal's_GDP_growth_rate_Nepal's_GDP_growth_rate_chartbuilder

The country’s finance minister, Ram Sharan Mahat, said earlier this week that Nepal urgently needs short-term funding, while the government begins work on chalking out a long-term plan.

The Nepal Economic Forum (NEF), an economic and policy research organisation, reported that the earthquake damaged 14 hydropower projects out of the at least 23 operational ones. This means a…

View original post 179 more words

Another major earthquake has hit Nepal


Quartz

This post will be updated as more information becomes available.

A little over two weeks after a massive earthquake-ravaged Nepal, the struggling Himalayan nation has just been hit by another big 7.3 magnitude quake.

The quake struck at about 12.30 pm local time on May 12, 76 km northeast of the capital city of Kathmandu, near the country’s border with China, according to the United States Geological Survey. Tremors were felt across eastern and northern India.

Screen Shot 2015-05-12 at 1.17.34 PM

With more than 8,000 dead and thousands more injured after the 7.8 magnitude earthquake hit on April 25, Nepal is already grappling with its worst natural disaster in decades.

Meanwhile, aftershocks—some as big as 6.3 magnitude—are continuing to hit. Here’s a map from the USGS, updated at 1.50 pm local time:

Screen Shot 2015-05-12 at 1.47.41 PM

Journalists in the area tweeted that locals rushed out of their houses as the tremblor hit.

View original post 109 more words