Disaster Safety Blog

New Madrid quake activity signals need for preparation

The New Madrid fault line has been rumbling again. And while an earthquake expert says the recent series of small quakes isn't unusual, it is a reminder of what the active fault is capable of, the St. Louis Post-Dispatch reports today.

Four small quakes have been centered near New Madrid in southeast Missouri in the past week, according to the U.S. Geological Survey. The largest was a magnitude 3.1 quake on Friday that was felt in parts of Missouri, Arkansas, Tennessee and Kentucky. No damage was reported. The others were a magnitude 1.7 on Dec. 15, a magnitude 1.3 on Dec. 16 and a magnitude 1.4 on Friday.

Robert Hermann of the Earthquake Center at Saint Louis University said a quake large enough to be felt happens about once a month in the region, and quakes with magnitude 2.0 and smaller happen on an almost daily basis.

In fact, according to a map on the Web site for the Center for Earthquake Research and Information in Memphis, Tenn., 15 earthquakes have occurred along or near the fault this month alone, including four on Friday. Only three were above a magnitude 2.0.

The fault line is best known for some of the most violent earthquakes to ever hit the U.S., a series of four in 1811 and 1812. The quakes were estimated at magnitude 7.5 to 8.0, so strong the Mississippi River reportedly flowed backward. Damage occurred as far away as Washington, D.C., and Charleston, S.C.
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Experts have long debated whether the fault line is capable of producing another major earthquake. Hermann isn't willing to bet that it won't, saying there's too much at stake to become complacent.

"Some argue that 1811 and 1812 were one-shot affairs, but it's prudent not to ignore that possibility, and it's prudent to take whatever steps are possible to prepare," he said.

Preparing for an earthquake can be as simple as anchoring cabinets, strapping down a water heater or using museum putty to secure valuables on shelves. Learn more with help from the Institute for Business & Home Safety (IBHS). Download a free earthquake preparedness guide. 

Don't let an earthquake turn your life upside down

A new art exhibit delves into the personal losses associated with the aftermath of an earthquake, MinnPost.com reports today.

The exhibition Quake/Temblor: A Forensics of Interior Life and Natural Disaster by Susannah Bielak is on display through Jan. 16 at Bethel University's Johnson Gallery in St. Paul, Minn. The multimedia installation includes video, drawings, prints, photography and engravings. View a photo gallery. 

Here is what MinnPost.com says about the exhibit:

"Quake/Temblor" is a perceptive but unsentimental reminder of just how closely our individual fates are tied with that of the natural world around us. It's well worth a visit to the gallery to see this show for yourself."

"The project," Bielak writes in her artist statement, "joins spaces of scientific testing, public memory, and private history — making reference to the Richter Scale, the broken city, and the kitchen table. Quake/Temblor aims to make visible some of what lies between everyday family life and the experience of an earthquake."

The installation is a composite creation, an archive of sorts recording both the geographic and human toll of large-scale natural disaster — using photographic and historical records of the 1985 quake, performative re-enactments (on video) of the event itself, and ingenious engraved pieces and prints, for which she's carved scenes of destruction on ordinary Formica kitchen tabletops.

Bielak describes going through old family photos one day and finding among them slides of the horrific aftermath of Mexico City's massive 1985 earthquake, all taken by her father. A civil engineer whose family roots lay in Mexico City, Bielak's father returned to his native home to document the quake's effects. She remarks that when she stumbled upon her father's photos, the juxtaposition of her family's intimate snapshots with images of such large-scale destruction was "destabilizing, pushing me to question the issue of terra firma in daily life."

It is possible to minimize the damage caused by earthquakes. Learn how with help from the Institute for Business & Home Safety (IBHS).

New shaketable unveiled during 25th anniversary at University of Nevada

The office swayed and jolted from side-to-side, the floor heaved upwards as the “earthquake” shook from below sending books off shelves, and pictures off the walls in the inaugural run of the new shake table this week at the University of Nevada, Reno’s earthquake simulation engineering lab, according to a university news report.

It was part of a celebration of 25 successful years of constructing and destroying large-scale buildings and bridges in the name of science, as well as the unveiling of the new 14-foot by 14-foot, triaxial 50-ton capacity shake table that moves in six different directions (horizontally in two directions, vertically, and pitch, yaw, and roll rotations). View a video of the demonstration.

“This is a wonderful occasion,” Milt Glick, president of the University of Nevada said. “We’re recognizing the past and the good things that have happened and at the same time showing the future.”

“The new, fourth shake table will greatly enhance our ability to more accurately represent the motions of an earthquake,” Ian Buckle, director of the Large Scale Structures Laboratory at the University said. The new table will be used individually as well as with the other three shake tables in the earthquake simulation lab for large-structure experiments such as a four-span bridge test to be conducted in the near future, he said.

 “For the demonstration of the new table, we built a room on the shake table, a typical office with furniture in it, and subjected it to three ground motions: last year’s magnitude 4.7 Mogul quake on the outskirts of Reno, the magnitude 6.7 Northridge, Calif. quake, and an extremely violent seismic motion used to qualify industrial equipment,” he said.” There was damage.”

Buckle and his crew built the office with two partial walls atop the shake table so the audience could view the dramatic results of the new $2.5 million table at the College of Engineering and Department of Civil and Environmental Engineering’s Large-Scale Structures Laboratory. The innovative table was designed and assembled by the engineering earthquake research team at the University with monetary support from the National Science Foundation and the Federal Highway Administration.

Through the Center for Civil Engineering Earthquake Research’s shared-use policies, research is carried out for federal and state agencies, the private sector and non-profit organizations. In addition to highway bridges, the Center’s current research efforts include the study of non-structural components in buildings and alternative building materials.

“The earthquake research done here at the University and in this laboratory has discovered new knowledge, stretched intellectual boundaries and at the same time provided useful research,” Glick said. “So when there’s a bridge problem in San Francisco, they call upon our faculty to help them solve the design problem. And when they want to design a safer building, where do they come? They come here.”

Almost 20 academic, research, and administrative faculty, research scientists, and technicians are affiliated with CCEER, and about 30 doctoral and masters students are engaged in research projects under the Center’s umbrella. Total research funding in 2009 was about $3.5 million. In its 25-year history the Center has published more than 160 technical reports which describe the results of these activities. In the past 10 years, major research grants and contracts acquired by the University’s Center for Civil Engineering Earthquake Research totaled $38.5 million.

The Large-Scale Structures Laboratory is a member of the George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) established by the National Science Foundation in 2004. As a NEES Equipment Site, the Laboratory is equipped with four, large-scale, high-performance shake tables; the only laboratory in the world of its kind

Learn more about preventing earthquake-related property damage with help from the Institute for Business & Home Safety (IBHS).

Nebraska rattled by rare earthquake

Southeastern Nebraska residents were rattled by a minor earthquake Wednesday night, the U.S.Geological Survey (USGS) reports. Earthquakes are uncommon in the state.

The USGS reported the 3.5 magnitude quake struck at 8:53 p.m. and was centered two miles north-northwest of Auburn.The quake was felt by people in several nearby Nebraska towns, including Peru, Nebraska City, Brock, Tecumseh, and across the Missouri River in Hamburg, Iowa.

Though not known for its earthquakes, Nebraska has experienced several notable shakes since its founding as a state in 1867. The USGS says the most serious of them was a magnitude 5.1 quake on Nov. 15, 1877, in the east-central part of the state.

The majority of damage caused by minor earthquakes occurs in a home's interior, where valuable electronics such as wall-mounted flat screen televisions can shift and often come dislodged. Appliances such as water heaters can topple, spilling water onto the floor and damaging surrounding furnishings and other valuables.

Learn how to secure the interior of your home or business with information from the Institute for Business & Home Safety (IBHS). Download a free guide today.

There’s a Whole Lot of Shaking Going On

Oklahoma County is experiencing more than twice as many earthquakes that can actually be felt this year than it usually does, according to the Oklahoma Geological Survey.

The biggest earthquake in Oklahoma this year measured 3.7 on the Richter scale and struck Aug. 28 in eastern Oklahoma County, near where three temblors have been recorded this month alone. While these were not large earthquakes, they still mean the earth is indeed moving in Oklahoma, and scientists do not know what is causing the increase in earthquakes in this area. 

Meanwhile, a small earthquake struck in what would seem like another unusual area last week – central Virginia. According to Virginia Tech's Seismological Observatory, a 2.7-magnitude earthquake caused light shaking in the area with some residents reporting pictures falling from walls and roof gutters falling.
The U.S. Geological Survey says that earthquakes of this size are actually not unusual in Virginia. In fact, earthquakes occur all over the U.S. as the earth continues to shake, rattle and roll.

Learn how to protect your home and business from being damaged by these seismic incidents with strategies from the Institute for Business & Home Safety (IBHS).

A.M. Best Special Report: New Hazard Maps, Model Updates Could Shift Views on Quake Risk

The 2008 National Seismic Hazard Maps by the U.S. Geological Survey are changing the perception of earthquake risk in the United States. Catastrophe modeling firms have updated their models with research from the latest maps, bringing potentially significant implications for how insurers and reinsurers manage, underwrite and price U.S. earthquake risk.

Newer USGS ground motion attenuation models tend to lower ground motion by up to 30% in the Western United States for shaking from 1-second seismic waves hitting multistory buildings.

Ground motion in the Central and Eastern United States is generally lower by about 10 percent to 25 percent, according to the USGS.
 
Insured loss estimates vary by region, coverage and modeler, but California quake risk is expected to show the largest changes. The latest 30-year California forecast also shows a greater chance of a strong quake near Los Angeles than San Francisco.

New views of quake risk in the Cascadia Subduction Zone incorporate a potential quake as strong as magnitude 9.2 that ruptures the entire zone, on average, every 500 years.
In the New Madrid Seismic Zone, the USGS treats events such as the 1811-1812 quakes as a sequence, which may have implications for insurers’ and reinsurers’ annual aggregate exposures there.

About 12.5 percent of California residential policies had quake coverage in 2008, versus 35 percent  of Missouri residential policies in 2007.
 
A full copy of the special AM Best report is available to BestWeek subscribers; non-subscribers can access an excerpt of each special report and purchase individual reports and spreadsheet data.

A dozen low-level earthquakes shake parts of California

An earthquake measuring 3.0 in magnitude shook the areas around Trona, Calif., just after 5 a.m. this morning,the U.S. Geological Survey reports.

The quake was just one of 11 aftershocks reports after a 4.6 magnitude quake was reported in parts of San Bernardino County on Monday. While no major property damage has been reported, local emergency officials are still surveying the area.
The most common form of damage from low-level earthquakes is caused by items that fall off walls, such as flat screen televisions, or appliances that shift or topple, such as water heaters.

Learn how to reduce the risk of earthquake damage with low-cost projects from the Institute for Business & Home Safety (IBHS).  

New Study Links Atmospheric Pressure to Quakes and Slides

 
Recent research that was published in the journal Nature Geosciences explains that atmospheric pressure changes associated with some weather systems could help trigger earthquakes, landslides, volcanic eruptions and even the movement of glaciers.

According the lead author William Schultz of the U.S. Geological Survey in Denver, it depends on the speed of the weather systems skirting above quake-prone regions. During periods of low pressure when there is less force exerted upon the ground, the upward movement of air and water molecules in the soil would serve to reduce the friction that usually holds the soil or rocks in place, potentially leading to landslides and earthquakes.

On the opposite side of the spectrum, long periods of unusually high atmospheric pressure, meaning extended periods of calm, quiet weather, could also trigger slides and quakes.

Based on the analyzing of a huge, extremely slow-moving landslide in southwestern Colorado for nine months, scientists examined how the slide was affected by atmospheric tides. They concluded that the slide’s progress was greater when the atmospheric pressure dropped at night, suggesting that there is a strong correlation between atmospheric perturbations and landslide movement.

New earthquake research sheds light on risk

New research reports that Southern California's San Jacinto fault experiences an average of four mini-earthquakes per day, which means it's constantly adjusting, and therefore is a less likely candidate for a major earthquake than its quiet neighbor to the east, the Southern San Andreas fault.

“Those minor to moderate events along the San Jacinto fault relieve some of the stress built by the constantly moving tectonic plates,” said Shimon Wdowinski, research associate professor at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, in a news release.

Previous estimates may have overstated the likelihood of a major event on the 140-mile long San Jacinto fault, which begins between Palm Springs and Los Angeles and runs south toward the Salton Sea east of San Diego, the release states.

The U.S. Geological Survey (USGS) is forecasting a 31 percent chance that an earthquake with a magnitude of 6.7 or higher on the Richter Scale will occur on the San Jacinto fault in the next 30 years.

Only the San Andreas fault, with a 59 percent chance, is more likely to have a major event during the same period.

“Thirty-one percent is a high probability, when it comes to earthquake forecasting—the second highest in Southern California,” said Wdowinski in the release. “Our data show that the next significant event for the San Jacinto fault would probably be between 6.0 and 6.7. It doesn’t sound like much, but in earthquake terms it is the difference between a major earthquake and a moderate event.” 

Even a moderate earthquake can cause significant damage to valuable property inside your home or business. Even the building remains structurally sound, wall-mounted televisions, water heaters and natural gas lines can shift to the point of causing major damage and even fire. The Institute for Business & Home Safety (IBHS) can help reduce this risk. 

A magnitude 6.0 earthquake may be felt for dozens of miles from the epicenter, but building damage especially in California, due to strict building codes, would be minimal.

As the magnitude approaches and passes 7.0, which is ten times stronger than an earthquake with a magnitude of 6.0, more serious property damage and loss of life may occur.

According to Wdowinski, the San Jacinto fault is not as dangerous as predicted, because “deep creep” releases elastic strain of the moving plates approximately six to ten miles beneath the surface.

Spend a little, save a lot when it comes to preventing quake damage

Earthquake Awareness Week in South Carolina ends tomorrow, but it has given residents an opportunity to better understand the state's risk from a disaster that is often far from top of mind for many.

The inability to forecast earthquakes makes them unlike other natural disasters that threaten the state, such as hurricanes and wildfires, Sumter County Emergency Management Director Robbie Baker told TheItem.com.

“You’re not going to have an advance warning for an earthquake. If we have a major earthquake, then there’s a good chance that the roads will not be passable. It could take several days before help arrives," Baker told the Web site. "In fact, you could be more isolated in an earthquake than in a hurricane. The only way to reach you after an earthquake could be by air.”

The state Emergency Management Division, the S.C. Earthquake Education Center at the College of Charleston, and the National Weather Service are sponsoring the awareness week to remind people that earthquakes pose a significant threat to South Carolina year-round, and citizens need to take proper precautions.

Many things residents need to do to prepare for earthquakes are quite inexpensive and can be done by a home or business owner with limited home improvement skills. For example, anchoring a water heater to the floor can reduce the chances it will tip over even in a minor earthquake. Preventing toppling reduces the risk of water damage and, if the water heater uses natural gas, minimize the chances of a fire following the earthquake. Learn more with free information from IBHS.

Although the state has fortunately not experienced a major earthquake in 95 years, it is important for residents to be aware that earthquakes have a history in South Carolina.

Here's a look back:

• In 1913, a quake with an estimated magnitude of 5.5 on the Richter scale hit Union.
• In 1886, an earthquake in Charleston killed 60 people and destroyed or damaged most buildings in the city. That historic earthquake, with a magnitude of 7.3, was felt as far away as Alabama and Florida, and is considered the most damaging earthquake to ever strike the Southeast.
• In 2000, an earthquake with a 2.43 magnitude was recorded in Lee County.