Italy earthquakes: Strong tremors shake central region

Italy earthquakes: Strong tremors shake central region

Italy earthquakes: Strong tremors shake central region : Two strong earthquakes have hit central Italy, damaging buildings and injuring dozens of people.
A 5.5-magnitude quake struck at 19:10 (17:10 GMT) near Visso in Macerata province, followed two hours later by a 6.1 magnitude tremor in the same area.
Emergency teams have worked through the night. In August an earthquake killed about 300 people south of Visso.
There are few reports of serious injuries, but bad weather has been hampering efforts to assess the damage.

August quakes: Why so many buildings collapsed

History of deadly earthquakes

Can quakes be predicted?

Visso is 70km (45 miles) from Amatrice, which was badly damaged in the 6.2 magnitude quake in August.

Wednesday’s earthquakes were felt across central Italy, including in the capital, Rome, where buildings shook, and doors and windows rattled.
“Tens” of people were hurt, but only four people suffered serious injuries, Italy’s civil protection chief Fabrizio Curcio said.
The second earthquake was considerably stronger than the first and numerous smaller aftershocks have occurred. One witness told Italian TV he saw part of a building collapse in front of him.

The town of Camerino is thought to have been badly damaged, and one resident told the BBC: “Everyone is leaving Camerino by foot or car to seek safety. Two churches are destroyed, and many houses [have] fallen.”
In Campo, near Norcia in the Umbria region, the late 15th century San Salvatore church collapsed. It had been weakened by the earthquake in August.
There are also reports of downed power lines, damage to historic buildings and a landslide on the main road north of Rome.

The first earthquake, 7km southwest of Visso, was relatively shallow, at a depth of 9km (nearly six miles). The second, at 21:18 local time, was 2km northwest of Visso, at a depth of 10km.
These tremors were linked to the August earthquake, Italian officials said.
“Aftershocks can last for a long time, sometimes for months,” AFP news agency quoted Mario Tozzi of Italy’s National Institute of Geophysics as saying.

Source : http://www.bbc.com/news/world-europe-37782320

Italy earthquakes: Strong tremors shake central region

Earthquake Faults Around San Francisco Are Dangerously Interconnected

Earthquake Faults Around San Francisco Are Dangerously Interconnected

Earthquake Faults Around San Francisco Are Dangerously Interconnected : Geologists have discovered that two deadly faults beneath San Francisco—the Hayward and Rodgers Creek faults—may be linked. Should one slip, it could trigger the other fault to collapse as well, causing an earthquake even larger than the one that struck back in 1989?

Geologists are very familiar with the Hayward Fault and its potential to unleash devastation along the populated subdivisions just east of San Francisco, but a new paper published in Science Advances by researchers from the US Geological Survey shows that a less-appreciated neighbor to the north, the Rodgers Creek Fault, may be connected. The discovery of a “missing link” between the two faults could change the way city officials plan for the next big earthquake in the Bay area.

Scientists are quite certain that the next major earthquake to strike the region will probably result from a rupture in either the Hayward or Rodgers Creek faults, but as the new research from USGS geologist Janet Watt and colleagues shows, these faults, which now appear to be interconnected, could rupture simultaneously. If that were to happen, it would produce a magnitude 7.4 quake along their combined 118 miles (190 km).

A quake of this strength would cause extensive damage and loss of life. And at a magnitude 7.4, such a quake would be five times stronger than the 6.9 Loma Prieta quake in 1989, which led to 63 deaths and nearly $10 billion in damages.

Previous work suggested that the two faults were separated by a two-mile wide buffer under the bay. The Hayward Fault stretches for 62 miles (100 km) from San Jose to San Pablo Bay, passing through Berkeley and Oakland, while the Rodgers Creek Fault runs 56 miles (90 km) north of the bay through the heart of northern California.

Watt’s team used high-resolution subsurface imaging to visualize the Hayward fault as it runs under San Pablo Bay. To their surprise, they discovered a previously undetected strand of the fault that bends toward and connects with the Rodgers Creek fault. Using computer models, the researchers found that the stress patterns fit in perfectly with visual observations of fault deformation and seismic activity in the area.

Because they’re interconnected, these two faults act as one, making it considerably easier for an earthquake rupture at either the northern or southern portions of the two faults to continue straight on through.

Source : http://gizmodo.com/earthquake-faults-around-san-francisco-are-dangerously-1788069171

Earthquake Faults Around San Francisco Are Dangerously Interconnected

How a Volcano in Japan Halted an Earthquake

How a Volcano in Japan Halted an Earthquake

How a Volcano in Japan Halted an Earthquake : Mount Aso, one of the most active volcanoes in Japan, recently helped to stop a powerful earthquake before it subsided on its own, researchers discovered.

When a 7.1-magnitude quake struck Kumamoto, Japan, on April 16, 2016, it opened surface ruptures in a zone extending 25 miles (40 kilometers) in length. But scientists found evidence suggesting that the powerful earthquake was halted by a magma chamber under the Aso volcanic cluster, located 19 miles (30 km) from where the quake originated.

This finding provided scientists with a rare glimpse of how two geological phenomena — volcanoes and earthquakes — may interact. This topic is of particular interest in Japan, which is particularly vulnerable to both volcanoes and earthquakes.
 An earthquake is a sudden release of pent-up energy in Earth’s crust that has accumulated over time, generated by shifting tectonic plates. When two sides of a fault, or crack along a plate boundary, move apart or slide suddenly past each other, energy gets released. The waves of energy radiate outward from that jolt, often producing shaking on Earth’s surface, according to the U.S. Geological Survey (USGS).

Japan is especially prone to earthquakes, as it lies in the Pacific Ring of Fire, a U-shaped area in the Pacific Ocean where several tectonic plates meet, and where many earthquakes are generated.

Some volcanoes are also found in this Ring of Fire. And it was the particular interaction of the April 2016 earthquake with the Mount Aso volcano that triggered the researchers’ interest in how seismic activity could be affected by the structure of volcanic clusters.

Shortly after the Kumamoto quake, the researchers visited the epicenter — the place on Earth’s surface directly above where the earthquake originated — and spent ten days investigating the ruptures left behind by the quake.

They discovered fresh ruptures that extended into Aso’s caldera — a large, bowl-shaped depression at the volcano’s summit — from the southwest to the northeast edge. And they abruptly ended there, at depths of 3.7 miles (6 km) below the surface.

Investigations of seismic activity deep under the caldera where the ruptures stopped indicated that there was a chamber holding magma — the same hot, fluid material called lava when it reaches Earth’s surface — at that very spot,

Energy waves from the quake traveled toward Mount Aso through cool, brittle rock, the study authors wrote. But the sudden encounter with the extreme heat generated by rising magma under the volcano dispersed the energy upward and outward, sapping the strength of the quake’s flow and stopping the rupture, they explained.

“This is the first case concerning the interaction between the volcano and co-seismic rupturing as we know so far,” study lead author Aiming Lin told Live Science in an email.

Lin, a professor in the Department of Earth and Planetary Sciences at the Faculty and Graduate School of Science at Kyoto University in Japan, said that although this is the first reported evidence of a volcano putting a stop to an earthquake, there are other historical examples that could represent similar activity.

In 1707, ruptures generated by the Houei-Tokai-Nankai earthquake (magnitude 8.7) extended northward and eventually terminated at the western side of Mount Fuji, Lin wrote. And in 1930, the rupturing of the magnitude-7.3 North Izu earthquake was interrupted at the Hakone volcano in Izu Peninsula.

“Along with this line, we are studying the interaction between the active faults — including co-seismic rupturing — and large earthquakes in Japan,” Lin said.

This discovery could help researchers more accurately anticipate earthquakes’ duration about their interaction with volcanoes, according to seismologist Gregory Beroza, deputy director of the Southern California Earthquake Center and a professor of geophysics at Stanford University.

“What it might mean for earthquakes is that magmatic systems might segment faults and, by doing so, limit the size of earthquakes in a predictable way,” Beroza, who was not involved in the study, told Live Science in an email.

“This is just one earthquake, however,” Beroza added. “No matter how interesting it is, or compelling it looks, it’s potentially hazardous to generalize to future earthquakes.”

Source : http://www.livescience.com/56571-how-volcano-stops-an-earthquake.html

How a Volcano in Japan Halted an Earthquake

The next earthquake to hit the Bay Area could be stronger than we thought

The next earthquake to hit the Bay Area could be stronger than we thought

The next earthquake to hit the Bay Area could be stronger than we thought: Two major earthquake-generating faults in California’s Bay Area may be connected. That means that the next temblor to shake the Bay’s 7 million or so residents could be much stronger — and much more destructive — than seismologists are anticipated, new research shows.

The study, published today in the journal Science Advances, shows that earthquake forecasts for the Bay Area could be underestimating the magnitude of a future quake. The US Geological Survey (USGS) estimates that there’s a 72 percent chance a dangerous quake might shake the area in the next 30 years; the earthquake could be at least as powerful as Southern California’s magnitude 6.7 Northridge quake in 1994 that killed 60 people and left 20,000 homeless. Knowing how strong a future quake could be is critical for disaster preparation.

The two faults described in today’s study, which is both parts of the San Andreas fault system, are well known to scientists. One is the Hayward fault, which stretches from the southern tip of the San Francisco Bay to the northern inland bulge that forms the San Pablo Bay. Another is the Rodgers Creek fault, which starts on the northern edge of San Pablo Bay and continues deep into wine country.

Whether — and how — these two faults connect underneath San Pablo Bay has been a mystery for years. But knowing if in fact they do is important, since quakes travel along a fault’s length: that means a longer fault can produce a bigger magnitude quake. (However, most earthquakes don’t travel the full length of a fault because bands, steps, and other geological discontinuities can stop the quake in its tracks).

A team of scientists led by Janet Watt with the USGS used a kind of high-resolution sonar to visualize shallow depths in the Earth’s surface beneath San Pablo Bay. The researchers looked for the telltale signs of a fault — areas where lines of sediment suddenly jump, or bend. They also looked at magnetic anomalies in the area, which can reveal changes in mineral composition typical of faults. By combining the underground images with magnetic analysis, the researchers concluded that the Hayward fault bends about 10 degrees to the right to connect smoothly with the Rodgers Creek fault underneath San Pablo Bay. Watt first presented this research last winter at the American Geophysical Union conference.

“This opens up the possibility of an earthquake that could rupture through this connection,” Roland Burgmann, a seismologist at the University of California, Berkeley who was not involved in the study, tells The Verge in an email.

Last year, Bergmann and other seismologists discovered that the Hayward fault also extends south to connect with the Calaveras fault, which stretches about 70 miles from near Mount Diablo to the Salinas Valley. Adding the Rodgers Creek fault to the north now means that there’s a wider range of earthquake sizes and lengths that could occur along this fault system, Bergmann says.

“How these two faults connect underneath San Pablo Bay has been a mystery for years “

Right now, predicting exactly when and where a quake will strike is impossible. But sensors deployed near fault lines can pick up the first waves of a quake and send an alert before those waves reach population centers. During the 2014 South Napa earthquake, the USGS’s early warning system called ShakeAlert gave test users in Berkeley a five-second warning before the shaking started. That could give people enough time to turn off gas lines and stop trains if they were ready to.

In August, the USGS distributed $3.7 million to six universities working on the next generation of ShakeAlert — but it’s going to take a sizable investment to develop it into a functioning public warning system. In June, the State of California budgeted $10 million for the early warning system, but that falls short of the $38.3 million the USGS estimates it will need to finish developing and deploying ShakeAlert across the West Coast, and $16.1 million every year to maintain it.

In the meantime, better understanding the fault system that could cause the next big earthquake is the only way to plan for a possible worst case scenario — a 7.4 magnitude earthquake. That’s five times stronger than the Loma Prieta quake that shook San Francisco in 1989, killing 63 people and causing $6 billion in damage. “It is a scenario we shouldn’t rule out,” Bergmann says. “That is important when it comes to being prepared for the biggest possible earthquake we believe we can have in the East Bay area.”

Source : http://www.theverge.com/2016/10/19/13335816/earthquake-faults-san-francisco-oakland-bay-area-san-andreas-hayward

The next earthquake to hit the Bay Area could be stronger than we thought

Earthquake hazard buildings may be forced to retrofit

Earthquake hazard buildings may be forced to retrofit

Earthquake hazard buildings may be forced to retrofit : PORTLAND, Ore. — The Portland City Council is looking into a new requirement for people who own old buildings. Soon, the city may require them to pay a lot of money to have those buildings retrofitted to handle an earthquake.

About 1,700 buildings in Portland have been identified by the city to have unreinforced masonry. Those buildings include apartments, businesses, schools, fire stations, and churches. Some are in the process of being upgraded.

They were built before 1960 when the danger of a catastrophic earthquake wasn’t a priority. Their bricks or concrete aren’t secured.

The Bureau of Emergency Management is writing up a proposal that would require owners fix these buildings.

“Some of the things property owners can do is brace parapets and cornices. They can make sure they have strong, solid chimneys, and they can also brace the floors of those walls, so when the ground does start shaking, the buildings can absorb some of that shock,” said Felicia Heaton of the Bureau of Emergency Management.

The city council will vote on the issue by the end of the year. Building owners would have between 10 and 25 years to comply.

Reinforcing those buildings could cost between thousands and millions of dollars depending on the size.

City Liquidators on Southeast 3rd Avenue and Morrison Street is on the list of hazardous buildings. The family company owns six blocks in the area and says it would cost around $30 million to reinforce all of them, and it would put them out of business.

Emma Pelett of City Liquidators said the work would be virtually pointless because their buildings are in the city’s “liquefaction” zone, wherein a large earthquake the areas closest to the river would turn to liquid and flow into the water.

While it would mean everyone is safer in the long term, those expenses could pass along higher rents for the tenants, or businesses closing in the short term. The requirement would not affect private homes or duplexes.

Because of the unpredictability of earthquakes, the city says it’s in all of our best interests to shore up these buildings. They say you could be walking by one, or live or work next door to one when bricks start falling.

“Having property owners invest in these retrofits would make these buildings safer. It would give people more time to evacuate a building after the ground stops shaking, and then potentially it would save these buildings from being demolished after an earthquake,” Heaton said.

Wednesday, Oct. 19, is the final tenant’s forum. The city wants to hear what renters think of the requirement. It’s at the St. James Lutheran Church downtown, at 1315 SW Park Ave., at 6 p.m.

Source : http://www.kgw.com/news/local/earthquake-hazard-buildings-may-be-forced-to-retrofit/337746243

Earthquake hazard buildings may be forced to retrofit

3.4 magnitude tremor hits Oudtshoorn

 3.4 magnitude tremor hits Oudtshoorn

 3.4 magnitude tremor hits Oudtshoorn : Cape Town – A tremor measuring 3.4 on the Richter Scale was experienced in the Southern Cape on Tuesday morning, the George Municipality has confirmed.

“The area experienced seismic activity this morning at approximately 08:25,” said spokesperson Chantel Edwards-Klose.

“The tremor ran 6km deep along the Cango faultline. The Cango Caves have been temporarily closed to assess, but no damage has been reported so far anywhere.”

She said the Council for Geoscience is in contact with Eden Disaster Management, although the tremor is considered low grade.

According to senior scientist Eldridge Kgaswane at the Council for Geoscience, who monitor seismic activity across SA, the earthquake occurred around the Prince Albert area.

“Preliminary indications are that it is a natural earthquake at a depth of roughly 5km and occurred in a remote mountainous area,” he said, adding that they have not received any reports from the Cango Caves at this stage.

In February, a mini earth tremor was experienced in parts of KwaZulu-Natal.

It lasted about four seconds and was felt from Richards Bay all the way to the Midlands.

It reportedly measured 3.1. No injuries were reported.

Source : http://www.news24.com/SouthAfrica/News/small-quake-hits-oudtshoorn-20161018

3.4 magnitude tremor hits Oudtshoorn

6.4 Magnitude Earthquake Shakes Yushu Tibetan Prefecture

6.4 Magnitude Earthquake Shakes Yushu Tibetan Prefecture

6.4 Magnitude Earthquake Shakes Yushu Tibetan Prefecture : A 6.4 magnitude earthquake rattled Tibet early Monday, followed by at least two strong aftershocks.

No casualties have been reported. One Tibetan nomad from a neighboring region tells VOA Tibetan Service no major damage has been reported, although cracks had appeared on numerous buildings.

U.S. Geological Survey observations indicate the epicenter is in sparsely populated Atod Xiang, about 249 kilometers west of Yushu City, also known as Kyergudo, where in 2010 a 7.1 magnitude quake killed at least 2,698 people.

China’s Xinhua state news agency says local authorities are investigating the extent of damage, and the school has been suspended for the day.

The shallowness of the quake and its proximity to the Zatoe County seat would typically indicate more destruction, said USGS seismologist Zachary Reeves.

“Damages depend on the infrastructure of the region as well as the size of the earthquake, but 29 kilometers is pretty close for earthquakes of this size,” he told VOA, adding that the 4.6- and 4.2-magnitude aftershocks respectively occurred 20 and 70 minutes after the main quake.

The overall population of Atod, which is located West of Yushu Prefecture and borders Drachen County of Nagchu Prefecture in Tibetan Autonomous Region, is more than 58,000.

Source : http://www.voanews.com/a/earthquake-shakes-yushu-tibetan-prefecture/3554867.html

 

6.4 Magnitude Earthquake Shakes Yushu Tibetan Prefecture

Today marks 27 years since the Loma Prieta Earthquake

Today marks 27 years since the Loma Prieta Earthquake

Today marks 27 years since the Loma Prieta Earthquake : OAKLAND (KRON) — Today marks the 27th anniversary of the devastating Loma Prieta earthquake.

The earthquake which killed 63 people in Oakland, San Francisco, and Santa Cruz. It damaged 12,000 homes and 2,600 businesses and caused an estimated $6 billion in damage.

The 25th anniversary of the Oakland-Berkeley Hills Fire is also this week, on Wednesday, marking a quarter-century since the firestorm killed 25 people, destroyed more than 3,000 homes and caused about $1.5 billion in damage.

In the years since the U.S. Department of Homeland Security’s Federal Emergency Management Agency has leveraged $201 million to reduce future damages from Bay Area earthquakes and fires, according to FEMA spokeswoman Mary Simms.

These funds, which are leveraged with state funds to cover about 75 percent of a project’s cost, have been used for seismic retrofits, fire risk reduction and flood elevation projects to protect homes and other local infrastructure.

FEMA recently approved a $3 million grant for the Safer Housing for Oakland: Soft Story Apartment Retrofit Program, which will retrofit between 35 and 50 Oakland apartment buildings, Simms said.

Another $3 million was approved for the Earthquake-Safe Homes Program, which will retrofit up to 300 one- to four-unit homes in Oakland.

FEMA also awarded $4 million in flood mitigation elevations in Sonoma County this year, Simms said.

Bay Area Rapid Transit is on track to complete the renovations planned in its Earthquake Safety Program, which was originally budgeted for $1.3 billion, including $980 million in bonds approved by voters in 2004, Simms said.

BART is set to complete the work, including retrofitting nearly 90 miles of track, $30 million under budget. BART engineers expect the Transbay Tube and much of the system, in general, to be able to withstand a 500-year seismic event, Simms said, adding that key BART structures are safer than many East Bay buildings.

Thursday is International ShakeOut Day when schools, businesses and local and state government agencies will hold earthquake drills at 10:20 a.m. local time.

Source : http://kron4.com/2016/10/17/today-marks-27-years-since-the-loma-prieta-earthquake/

Today marks 27 years since the Loma Prieta Earthquake

6.4 magnitude earthquake hits northwest China

6.4 magnitude earthquake hits northwest China

6.4 magnitude earthquake hits northwest China : BEIJING – A 6.4 magnitude earthquake struck China’s northwestern province of Qinghai on Monday, the US Geological Survey reported, in an area frequently plagued with seismic activity.The quake was 32 kilometers (20 miles) deep, USGS said, with its epicenter in a sparsely-populated area of Yushu prefecture. There was a “low likelihood of casualties and damage”, it said.

Yushu was the scene of a 6.9-magnitude earthquake in April 2010 that left nearly 2,700 people dead and more than 12,000 injured, according to state news reports.

In 2011 it was struck by a 5.3-magnitude quake.

The China Earthquake Network Centre gave the latest tremor a magnitude of 6.2 and a depth of nine kilometers, with its epicenter in Zadoi county.

Source : http://www.bangkokpost.com/news/asia/1112637/6-4-magnitude-earthquake-hits-northwest-china

6.4 magnitude earthquake hits northwest China

6.4 magnitude earthquake strikes Tibet

6.4 magnitude earthquake strikes Tibet | USGS

6.4 magnitude earthquake strikes Tibet : A 6.4 magnitude earthquake has shaken the Himalayan region of Tibet, China, the US Geological Survey reported, adding that the depth of the quake was about 32km.

The tremor took place 17km from the Chinese town of Aduo and 294 km from the city of Chamdo, the USGS reported.

The quake’s epicenter was about 509km from the city of Lhasa, the capital of the Tibet Autonomous Region.

The Himalaya region is considered to be one of the most seismically hazardous regions on Earth. It’s high seismicity results mostly from the continental collision of the Indian and Eurasian plates.

Source : https://www.rt.com/news/362992-tibet-hit-earthquake-usgs/

6.4 magnitude earthquake strikes Tibet

Papua New Guinea earthquake: 6.9 magnitude quake strikes off coast

Papua New Guinea earthquake: 6.9 magnitude quake strikes off coast

A 6.9 magnitude earthquake has struck off the coast of Papua New Guinea.

The US Geological Survey detected the epicenter near New Britain, Papua New Guinea’s largest offshore island, at 4.15pm local time (7.15am BST).

It came days after another tremor measuring 6.4 hit the same region. There was no immediate information on casualties or damage.”Based on all available data, there is no tsunami threat from this earthquake,” a notice said.

Papua New Guinea lies on the Pacific “Ring of Fire” – a volcanically active region subject to frequent earthquakes, tsunamis, and volcanic eruptions.

In July 1998, two undersea quakes measuring 7.0 on the Richter scale created three tsunamis that killed at least 2,100 people near the town of Aitape.

Source : http://www.independent.co.uk/news/world/australasia/papua-new-guinea-earthquake-today-69-magnitude-quake-strikes-off-coast-location-epicentre-damage-a7364951.html

Papua New Guinea earthquake: 6.9 magnitude quake strikes off coast