Science Features » Earthquakes

Does Solar Activity Cause Earthquakes?

Aqsa Ahmed — Fri, 03 May 2013 11:49:02 +0000

The sun affects space weather, but does it cause earthquakes?

Many have wondered whether solar activity can be linked to earthquakes, but a recent study found no direct relationship between the two.

Scientists assembled historical records of the Sun’s interaction with Earth, looking at sunspots, solar wind, and magnetic storms. They then compared these with historical records of earthquake occurrence. They found no significant pattern between solar activity and more or larger earthquakes. There is no demonstrated way to use space data to predict future earthquakes.

The study was recently published in the journal Geophysical Research Letters. The research was conducted by Jeffrey Love with the USGS and Jeremy Thomas from Northwest Research Associates. The earthquake data were from the USGS, the sunspot data were from NOAA, the solar wind data were from NASA, and the geomagnetic data were from the British Geological Survey and Geoscience Australia.

The Author’s Perspective

“This research was conducted to advance our understanding of natural science and to test how the Sun affects Earth, ultimately helping protect the safety of our communities,” said USGS research geophysicist Jeffrey Love. “Even though we did not find a significant correlation between space measurements and earthquakes, we recognize that the Sun affects Earth in other ways. The USGS is dedicated to studying these natural phenomena, some of which are hazardous for a modern and technologically dependent society.”

“Of course it is always conceivable that some new and unexpected discovery will be made in the future, but it is also essential that we objectively evaluate the data and information that we have available now,” continued Love. “Just because one might think that a pattern exists does not mean that one actually exists. We need clear evidence to be convinced.”

Types of Solar and Space Activity

Everyone is familiar with weather systems on Earth like rain, wind, and snow. But space can also have a “weather” of sorts. The Sun’s behavior changes over time and this can cause the space environment surrounding Earth to change as well.

Magnetic storms, for example, are periods of time when Earth’s magnetic field is unusually active. How do they occur? The Sun is always emitting a wind of electrically charged particles, and when that happens abruptly, it can cause a magnetic storm.

Space weather can have important consequences for our lives on Earth’s surface. Large magnetic storms can cause the loss of radio communications, reduce the accuracy of GPS systems, damage satellite electronics and affect satellite operations, increase pipeline corrosion, and induce voltage surges in electric power grids, causing blackouts. It is during magnetic storms that beautiful aurora borealis — or “northern lights” — are visible at high latitudes.

Now let’s talk about sunspots. A sunspot is a visibly dark region on the solar surface that corresponds to a concentration of solar magnetic energy and activity. If and when a large sunspot emerges on the face of the Sun, there is an increased chance for abrupt emission of strong solar wind velocity, and this can result in large magnetic storm at Earth. The number of sunspots waxes and wanes over the course of an 11-year solar cycle. The current cycle is unusually tame, but it could still change over the next few years.

Haitian woman carrying supplies amid the destruction from the January 2010 Haiti earthquake.

USGS Role

The USGS Geomagnetism Program operates 14 observatories around the United States and its territories, which provide real-time ground-based measurements of the variable geomagnetic field. These measurements are used internally by the USGS, and they are used by partners in the United States National Space Weather Program, including NOAA, NASA, and the U.S. Air Force, to track the intensity of the magnetic storms generated by the Sun and its interaction with the Earth. The USGS Geomagnetism Program has also been working cooperatively with private industries that are affected by space weather and geomagnetic activity, including electric-power grid companies and the oil and gas drilling industry.

Can We Predict Earthquakes?

So far, the answer is no. Despite frequent claims to the contrary, no reliable short-term earthquake prediction method has ever been developed. Nor do scientists expect to develop a method in the foreseeable future.

However, based on scientific data, probabilities can be calculated for future earthquakes. For example, comprehensive assessments of long-term earthquake rates in California tell us there is roughly a 2-in-3 chance that a magnitude 6.7 or larger earthquake will strike in the next 30 years in the greater San Francisco Bay Area. Within the State of California as a whole, earthquakes this large are virtually certain (a 99 percent probability) in that same time frame.

Knowing the likelihood of future earthquakes allows prudent actions to be taken to mitigate their effects, no matter when they may happen to strike.

Listen to a podcast on earthquake prediction with Mike Blanpied, Associate Coordinator of the USGS Earthquake Hazards Program.

Climate Change and Solar Storms

Are solar storms related to climate change? Find out the answer by watching USGS Climate Connections.

Get Ready to ShakeOut on February 7

Aqsa Ahmed — Tue, 29 Jan 2013 12:50:55 +0000

Students participate in the Great Southeast ShakeOut earthquake drill at Langston Hughes Middle School in Reston, Virginia. They are conducting the “drop, cover and hold on” safety procedure.

More than 2.7 million people are currently signed up to simulate recommended safety actions during an earthquake in nine states – Tennessee, Oklahoma, Missouri, Alabama, Arkansas, Kentucky, Indiana, Illinois and Mississippi.

You are invited to join millions of people who will Drop, Cover, and Hold On at 10:15.a.m. on February 7, 2013* in the 2013 Great Central U.S. ShakeOut!

Last year more than 12.5 million people were registered in ShakeOut drills worldwide. Participating is a great way for your family or organization to be prepared to survive and recover quickly from big earthquakes.

During the drill, participants will “drop, cover, and hold on.” This is the recommended safety action to take during an earthquake.

Millions of people have participated in ShakeOut drills since 2008. The drill is your chance to practice how to protect yourself and do your part to help prevent a major earthquake from becoming a catastrophe.

Earthquake Hazard in the Central U.S. Remains a Concern

There is broad agreement in the scientific community that a continuing concern exists for a major destructive earthquake in the New Madrid seismic zone. Many structures in Memphis, Tenn., St. Louis, Mo., and other communities in the central Mississippi River Valley region are vulnerable and at risk from severe ground shaking. This assessment is based on decades of research on New Madrid earthquakes and related phenomena by dozens of Federal, university, State, and consulting earth scientists.

This will be the third year an earthquake preparedness drill is officially held in the central United States. Even if you don’t live in one of these locations, this is an important exercise as earthquakes are a hazard worldwide. Keep in mind that you might travel somewhere where an earthquake could occur. Everyone, everywhere, is encouraged to participate in the ShakeOut.

Sign Up and ShakeOut

Although the ShakeOut is TOMORROW, it is not too late to register to participate. Mark your calendar and register for the ShakeOut drill near you. Families, schools, businesses, and organizations can all get involved and sign up.

There are many ways to participate, and a variety of resources and tips are provided online. This includes pre-made flyers, drill broadcast recordings, drill manuals, and more.

What to Do During the Drill

The drill will begin at 10:15 a.m. local time. If you are indoors, you should “drop, cover, and hold on.” Drop to the floor, take cover under a sturdy desk or table, and hold on to it firmly. If you are not near a desk or table, drop to the floor against the interior wall and protect your head and neck with your arms. Avoid exterior walls, windows, hanging objects, mirrors, tall furniture, large appliances, and kitchen cabinets with heavy objects or glass.

While down on the floor, take a moment to look around at what could be falling during a real earthquake. Those items should be secured or moved after the drill.

During an earthquake, the recommended safety action is to “drop, cover, and hold on.”

If you happen to be outdoors, move to a clear area if you can safely do so. Avoid power lines, trees, signs, buildings, vehicles, and other items that could fall on you. If you are driving, pull over to the side of the road, stop, and set the parking brake. Avoid stopping under overpasses, bridges, power lines, or traffic signs. Stay inside the vehicle until the shaking is over.

USGS Science in ShakeOut

The U.S. Geological Survey (USGS) is a proud founder and supporter of ShakeOut.

Students participate in the Great Southeast ShakeOut earthquake drill at Langston Hughes Middle School in Reston, Virginia. They are conducting the “drop, cover and hold on” safety procedure.

The USGS has created and provides information tools to support earthquake loss reduction, including hazard assessments, scenarios, comprehensive real-time earthquake monitoring and public preparedness handbooks. USGS science provides the basis for earthquake scenarios that shape preparedness exercises such as the ShakeOut. USGS earthquake hazards research helps emergency managers understand where earthquakes occur and what the potential damages and losses would be.

The original ShakeOut was based on a comprehensive analysis of a major earthquake in southern California known as “The ShakeOut Scenario.” That project was completed in 2008 and led by the USGS with many partners as a demonstration of how science can be applied to reduce risks related to natural hazards. The concept and organization of a public drill came out of the collaboration between the USGS, the Southern California Earthquake Center (SCEC), and other partners through the Earthquake Country Alliance (ECA). SCEC is a research consortium funded in part by the USGS. ECA is a public-private partnership of people, organizations, and regional alliances that are led by SCEC and work together to improve preparedness, mitigation, and resiliency by supporting and coordinating efforts that improve earthquake and tsunami resilience.

The success of the 2008 ShakeOut spurred the organizers at ECA to take the concept worldwide, and turn it into an annual day of disaster preparedness activities. Nationwide, ShakeOut activities are now coordinated and supported by many agencies and partners including SCEC, the Federal Emergency Management Agency (FEMA), the National Science Foundation (NSF), the Central United States Earthquake Consortium (CUSEC), the American Red Cross, and others.

The USGS provides rapid alerts of potential impacts from an earthquake through its Prompt Assessment of Global Earthquakes for Response (PAGER) system. Sign up to receive earthquake notices through the USGS Earthquake Notification System. If you feel an earthquake, report your experience on the USGS “Did You Feel It?” website.

Learn More

Students participate in the Great Southeast ShakeOut earthquake drill at Langston Hughes Middle School in Reston, Virginia. They are conducting the “drop, cover and hold on” safety procedure.

Learn how to prepare at home using the 7 Steps to Earthquake Safety from “Putting Down Roots in Earthquake Country” written for different areas of the country and in several languages.

Find out more about why the Earthquake Hazard in the New Madrid Seismic Zone Remains a Concern.

Additional information on what you can do to prepare for earthquakes at work and home is available on the Great ShakeOut website.

USGS CoreCast

ShakeOut Drill: Preparing for Earthquakes

Recorded for the October 18, 2012 Great ShakeOut held in the southeastern United States.

Transcipt and Details

Get Ready to ShakeOut on October 18

Scott Horvath — Fri, 12 Oct 2012 11:00:26 +0000

You are encouraged to participate in the Great ShakeOut earthquake drill to be held on October 18, 2012.

Children participating in an earthquake drill on April 23, 2009, at the British School in Tokyo, Showa Campus. The drill is based on the Japanese Earthquake Early Warning System.

During the drill, participants will “drop, cover, and hold on.” This is the recommended safety action to take during an earthquake.

This will be the first year an earthquake preparedness drill is officially held in the southeastern United States. The Great Southeast ShakeOut includes Georgia, South Carolina, North Carolina, Virginia, Maryland, and the District of Columbia. Official ShakeOut drills will also be held on October 18 in Alaska, Arizona, British Columbia, California, Guam, Idaho, Nevada, Oregon, Puerto Rico, southern Italy, and Washington.

Even if you don’t live in one of these locations, this is an important exercise as earthquakes are a hazard worldwide. Keep in mind that you might travel somewhere where an earthquake could occur. Everyone, everywhere, is encouraged to participate in the ShakeOut.

Sign Up and ShakeOut

Although the ShakeOut is just days away, it is not too late to register to participate. Mark your calendar and register for the ShakeOut drill near you. Families, schools, businesses, and organizations can all get involved and sign up.

There are many ways to participate, and a variety of resources and tips are provided online. This includes pre-made flyers, drill broadcast recordings, drill manuals, and more.

What to Do During the Drill

The drill will begin at 10:18 a.m. local time. If you are indoors, you should “drop, cover, and hold on.” Drop to the floor, take cover under a sturdy desk or table, and hold on to it firmly. If you are not near a desk or table, drop to the floor against the interior wall and protect your head and neck with your arms. Avoid exterior walls, windows, hanging objects, mirrors, tall furniture, large appliances, and kitchen cabinets with heavy objects or glass.

While down on the floor, take a moment to look around at what could be falling during a real earthquake. Those items should be secured or moved after the drill.

During an earthquake, the recommended safety action is to “drop, cover, and hold on.”

USGS Science in ShakeOut

The U.S. Geological Survey (USGS) is a proud founder and supporter of ShakeOut.

USGS employees across the nation are signing up to participate in the drill, raising awareness and providing an opportunity to test occupant emergency plans.

Podcast

Listen to a podcast interview on ShakeOut. The interview is with Mike Blanpied, who is the Associate Program Coordinator for the USGS Earthquake Hazards Program, as well as Mark Benthien, who is the Director of Communication, Education and Outreach with SCEC and coordinates the Great ShakeOut worldwide.

Learn More

Learn how to prepare at home using the 7 Steps to Earthquake Safety from “Putting Down Roots in Earthquake Country” written for different areas of the country and in several languages.

News media can also find information online regarding events, contacts and other items of interest.

Additional information on what you can do to prepare for earthquakes at work and home is available on the Great ShakeOut website.

A History of Rubble and Rumblings: Earthquakes in the Eastern U.S.

apdemas — Mon, 27 Aug 2012 19:32:16 +0000

This map shows recorded earthquakes in the central and eastern United States lain over the USGS earthquake hazard maps.

Last year’s M5.8 Virginia earthquake came as a surprise for many in the area, but in the past 400 years, there have been more than 30 damaging earthquakes in the eastern U.S., ranging from the M6.0 near Boston in 1755, to M7.3 in Charleston, S.C. in 1886. Despite this history of earthquakes the faults on which these earthquakes are occurring are poorly known, and scientists do not have a clear understanding of the causes of earthquakes in the eastern U.S. Scientists are using seismic data from the August 2011 M5.8 Virginia earthquake to answer some of these questions and to refine estimates of the of the region’s seismic hazard. Futures damaging eastern earthquakes are inevitable; join us on September 5 to find out what scientists are learning and how you can prepare for the next big one.

Time: Wednesday, September 5, 2012 • 7-8pm
Speaker: Robert Williams
Location: 12201 Sunrise Valley Drive Reston, VA 20192
Phone: 703-648-4748

Please Note: This event takes place at a Federal Facility — Photo Id is Required
FREE and Open to the Public

Follow this event live on Twitter @USGSLive
This announcement and directions can be found online.

Requests for accommodations (i.e. sign language interpreting) require notice at least two weeks before the event. Please email jcorley@usgs.gov or call 703-648-7770.

The USGS public lectures are held monthly in Reston, Virginia. These evening events are free to the public and intended to familiarize a general audience with science issues that are meaningful to their daily lives. USGS speakers are selected for their ability and enthusiasm to share their expertise with an audience that may be unfamiliar with the topic; speakers are encouraged to thoroughly explain the subject matter and to define any words or terms that may be unfamiliar.

The USGS lecture series provides the public an opportunity to interact with USGS scientists and ask questions about recent developments in Natural Hazards; Water; Energy Minerals and Environmental Health; Climate and Land Use Change; Ecosystems; and Core Science Systems. Ultimately, the goal is to create a better understanding of the importance and value of USGS science in action.

President Obama Honors 3 USGS Scientists with Presidential Early Career Awards

ademas — Tue, 24 Jul 2012 13:29:44 +0000

USGS research geologist Joe Colgan, research geologist Karen Felzer, and research geologist Justin Hagerty were honored by President Obama on July 23, 2012, with the Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed by the United States government on science and engineering professionals in the early stages of their independent research careers.

“Discoveries in science and technology not only strengthen our economy, they inspire us as a people,” President Obama said. “The impressive accomplishments of today’s awardees so early in their careers promise even greater advances in the years ahead.”

The Presidential early career awards embody the high priority the Obama Administration places on producing outstanding scientists and engineers to advance the Nation’s goals, tackle grand challenges, and contribute to the American economy.

USGS scientist Joe Colgan

Joe Colgan Has Pioneered Methods to Study Faults and Minerals in the West

Colgan’s research investigates the origins and evolution of the Basin and Range Province, a vast geologic region that covers much of the Western U.S. and parts of northern Mexico. Colgan integrates various scientific techniques, such as regional structural analysis, high-precision geochronometry, and geologic mapping, in order to learn more about the fault zones and mineral formations that exist in this region.

“Everyone at the USGS is cheering the President’s selection of Joseph Colgan for this highest honor!” said USGS Director Marcia McNutt. “It is such a stunning affirmation of our deeply held belief that tackling the Nation’s foremost issues such as providing new sources of energy and minerals or keeping people safe from natural hazards does not come at the expense of doing world class basic research.”

Presidential Early Career Awards for Scientists and Engineers

The Presidential Early Career Awards for Scientists and Engineers was established by President Clinton in 1996 and are coordinated by the Office of Science and Technology Policy within the Executive Office of the President. Awardees are selected for their pursuit of innovative research at the frontiers of science and technology and their commitment to community service as demonstrated through scientific leadership, public education, or community outreach.

Bringing Earthquake Science into Your Home

Aqsa Ahmed — Thu, 10 May 2012 14:15:56 +0000

NetQuakes strong-motion instruments enable seismologists to collect extensive data in urban areas where installing traditional seismographs is not practical. This instrument (in blue, to the right of the upended chairs) takes up very little space in a San Francisco Bay Area resident's garage. It is the size of a car battery, runs on a home wifi network and captures data on an ordinary 2GB flash drive.

Obtaining timely earthquake information has become easier with interactive earthquake maps and NetQuakes, a citizen-science program that helps scientists to understand ground shaking caused by earthquakes.

Newly updated website provides robust, real-time earthquake information

Whether an earthquake is minor or major, earthquake.usgs.gov visitors will see an interactive earthquake map that regularly updates, can be individually tailored, and provides saved settings for future map visits.

“For all citizens of ‘Earthquake Country,’ whether they reside in our Nation’s Capital or near a major global tectonic plate boundary, the new USGS earthquake site supplies increased functionality to provide more real-time information tailored to the viewer’s specific needs,” said USGS Director Marcia McNutt. “When the ground shakes and time is of the essence, our goal is to ensure that the most timely information is at the fingertips of those who need to know.”

From the website, you can access Latest Earthquakes to:

zoom into and pan the world map.
select different basemaps, as well as overlays such as plate boundaries, faults, and earthquake hazards.
display earthquakes on the map by time window, magnitude, depth, and maximum recorded intensity.
see a list below the map updates for the current map view and settings.
download earthquake lists into other map interfaces such as Google Earth (KML format) and Excel (CSV).

The event page, when an earthquake is selected, has also been upgraded and provides interactive features and more information, including downloadable data files in various formats for each earthquake product, such as ShakeMap and Did You Feel It? This new event-centric view allows you to see all the information associated with each earthquake without having to jump around the website to view each related product.

A future product in development will use the same user interface to present a seamless view of recorded world-wide earthquakes current and historical. It is anticipated that this product will be released in beta format later this year.

How do we gather earthquake data?

This device, about the size of a large shoebox, records strong ground motions and sends the measurements to the U.S. Geological Survey over the Internet. The data collected is available to assist with emergency response following an earthquake.

Seismic networks detect more than 87,000 earthquakes in the United States each year, although most of these quakes are too small to be felt by people. ShakeMaps, produced by the USGS and its university and State partners, give timely and detailed information on the shaking generated by quakes larger than magnitude (M) 3.5, which are often felt, are of interest to scientists, and are occasionally damaging. While the current monitoring system delivers earthquake information rapidly and reliably, seismologists are concerned that it will not fully record the damaging earthquakes that scientists have forecasted will occur. USGS scientists, however, have developed a cost-effective solution.

What is NetQuakes?

NetQuakes is a “citizen-science” program, developed in Menlo Park, Calif., by the USGS Earthquake Hazards Program , that offers the public the opportunity to help seismologists record earthquakes by hosting portable, low-maintenance sensors in private homes, public buildings, schools, and churches — and not just in the earthquake zones of California, but wherever seismic activity is a concern in the Nation. Hundreds of volunteers now host NetQuakes instruments, which transmit seismic data via Wi-Fi networks and the Internet to the USGS.

The NetQuakes project began in 2009 and was born of observations that came out of the September 2004 M6.0 earthquake near Parkfield, Calif.

“We learned from the Parkfield earthquake that intensity of ground motion amplitudes vary far more than we had believed,” said USGS geophysicist Jim Luetgert. “We had thought that sensors placed miles apart would give a good representation of the variations in shaking. But the Parkfield earthquake showed that a much closer spacing is needed to adequately map that variability.”

It’s complicated and expensive to place traditional seismographs in the urban areas that have sprung up in many seismically active areas. Traditional seismographic stations often require:

additional construction, such as a poured concrete foundation,
vandal-proof enclosures,
costly equipment that takes up the same space as a refrigerator, and
costs about $50 to transmit seismic data per station per month.

The NetQuakes instrument, in contrast, comes in an aluminum box the size and shape of a car battery. The instrument is attached to a metal baseplate that is bolted onto a foundation or floor. Rather than using GPS to keep accurate time as many traditional seismographs do, NetQuakes uses the network time protocol used by personal computers, which queries established Internet servers.

The instruments communicate occasionally with USGS computers, and telemetry is free to the USGS because hosts allow the instrument to communicate over their household Internet service. A 2GB-flash drive stores two weeks of data in case Internet communications fail in an earthquake. The instruments rely on power from a wall outlet, but contain an easily replaced internal battery to power the instrument for up to 36 hours should electricity fail.

The researchers are not looking to NetQuakes to record low-magnitude earthquakes or for rapid determination of location and magnitude, which is the role of the existing seismographic networks. Rather, they want to record how ground motion varies across a densely spaced array of high-quality sensors — especially during the largest earthquakes, which can produce ground accelerations up to three times the acceleration of gravity (3g).

Economically deploying large numbers of instruments has required some compromises. “Tradeoffs include levels of sensitivity and a few minutes of response-time,” Luetgert said. “The data are available within 10 minutes after the earthquake and are automatically incorporated into ShakeMap updates.”

For the first deployments, organizers sought a few volunteers from engineer and scientist friends near Stanford University and the University of California at Berkeley, where the Hayward Fault runs right through California Memorial Stadium. Today there are more than 130 NetQuakes instruments in the San Francisco Bay Area. Instruments have also been distributed to each of the regional networks in the USGS Advanced National Seismic System (ANSS). Luetgert noted that great progress has also been made in the Seattle area, which now has more than 80 NetQuakes instruments hosted by volunteers.

Traditional seismic stations such as this one require a source of power (solar here), a poured concrete foundation and several square feet of space. They are not always practical to install in urban areas, and that's where NetQuakes comes in.

The Portability of NetQuakes Has Advantages

Interest elsewhere has followed earthquake activity. Three years ago a swarm of small earthquakes in central Oklahoma occurred in an area devoid of seismic instruments, so Luetgert sent five instruments to NetQuake volunteers in that area. NetQuakes instruments were also deployed in the epicentral region of the August 2011 M5.8 earthquake near Charlottesville, Va., to locate aftershocks, as well as in the damaged National Cathedral in Washington, D.C. Three NetQuakes instruments were deployed near Youngstown, Ohio, to record earthquakes suspected to be induced by fluid injection in a deep well.

NetQuakes data are also being used to help resource managers and public agencies monitor shaking at critical facilities. The East Bay Municipal Utility District is partnering with the USGS to monitor ground motion at its suburban dams and reservoirs near the Hayward Fault in the eastern San Francisco Bay Area.

“Magnitude 6.8 earthquakes rupture the Hayward Fault on average every 140 years, and one may be coming due,” Luetgert noted. “We would like to be ready to record that earthquake with high-quality seismic instrumentation from a dense network to document the effects of the shaking in an urban area. This will enable engineers to better understand why buildings didn’t stand up to the shaking, and ultimately how to build structures that can resist shaking from future quakes. NetQuakes provides a cost-effective way to achieve that goal with the help of the public.”

Join Citizens and scientists tracking the pulse of our planet

Is the recent increase in felt earthquakes in the central U.S. natural or manmade?

Oklahoma struck by series of quakes

5.8 earthquake in Virginia

Earthquake Hazards Program deformation data sites:

Parkfield

San Francisco Bay Area

Southern California

Is the Recent Increase in Felt Earthquakes in the Central U.S. Natural or Manmade?

ademas — Wed, 11 Apr 2012 19:55:16 +0000

A map showing significant earthquakes in the midcontinental area analyzed for links between felt earthquakes and energy development.

This graph shows the cumulative number of earthquakes M 3 or greater in the midcontinental United States. The number of M3 or greater earthquakes increases steadily at about 21 events per year until around 2000, when it increases about 50% to 31 events per year. By 2008, the number increased sharply to about 151 events per year.

USGS scientists have been investigating the recent increase in the number of magnitude 3 and greater earthquakes in the midcontinent of the United States. Beginning in 2001, the average number of earthquakes occurring per year of magnitude 3 or greater increased significantly, culminating in a six-fold increase in 2011 over 20th century levels.

An increase in earthquakes such as this prompts an important question: are they natural, or man-made? To address this question, a team of USGS scientists analyzed changes in the rate of earthquake occurrence in the midcontinent using large USGS databases of earthquakes recorded since 1970.

Our scientists then took a closer look at earthquake rates in regions where energy production activities have changed in recent years. To learn more about their findings, please visit Deputy Secretary of the Department of the Interior David Hayes’ blog post here.

To learn more about the link between deepwell fluid injection, a method of the disposal of wastewaters from practices like hydraulic fracturing, and triggered earthquakes, please visit our FAQs.

Magnitude 8.6 Earthquake Strikes Northern Sumatra, Indonesia

ademas — Sun, 01 Apr 2012 15:07:20 +0000

A map showing the population exposure from the M 8.6 earthquake that struck off the west coast of northern Sumatra on April 11, 2012

A magnitude-8.6 earthquake struck off the west coast of northern Sumatra Wednesday, April 11, 2012, at 8:38 a.m., UTC. It was followed by a M-8.2 earthquake at 10:43 a.m. UTC. The estimated depths of these earthquakes are 14 and 10 miles respectively.

The M 8.6 event caused low to moderate shaking in the Sumatran cities of Sinabang and Meulaboh general alarm in costal areas of northwestern Sumatra where people rushed to higher ground. The National Oceanic and Atmospheric Administration issued a tsunami watch for both the M 8.6 and the M 8.2 earthquakes, but subsequently cancelled both.

The current version of the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) estimate is that economic losses are most likely to be less than $1 million range, and there are no expected fatalities.

A map showing the responses to the USGS Did You Feel It? tool following the April 11, 2012 M 8.6 earthquake off the west coast of northern Sumatra

The earthquake struck near the eastern edge of the Indian Ocean off the west coast of northern Sumatra. As of this writing, 1,912 people in 245 cities throughout northern Sumatra and the surrounding region had responded on the USGS Did You Feel It? website.

History of strong earthquakes

Sumatra is located in a tectonically active area, and it experiences frequent significant earthquakes. In 2004, this area experienced a M 9.1 earthquake that resulted in a significant tsunami. In total, 227,898 people were killed or were missing and presumed dead and about 1.7 million people were displaced by the earthquake and subsequent tsunami in 14 countries in South Asia and East Africa.

Magnitude 7.4 Earthquake Strikes Oaxaca, Mexico

ademas — Tue, 20 Mar 2012 20:02:54 +0000

A magnitude-7.4 earthquake struck in the Mexican state of Oaxaca Tuesday, March 20, 2012, at 12:02 p.m., local time at the epicenter. It was followed by a subsequent M-5.1 earthquake at 12:35 p.m. local time.

The earthquake occurred at a depth of 12 miles (20 km) and caused moderate shaking in Acapulco and Oaxaca. As of 3:13p.m. ET, the National Oceanic and Atmospheric Administration has issued no warning of tsunami activity.

The current version of the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) estimate is that economic losses are most likely to be in the $10-100 million range, and fatalities are equally likely to be in the 10-100 range.

The earthquake struck in the southwestern part of Mexico between Acapulco and Oaxaca. As of this writing, 859 people in 144 cities throughout Mexico and the surrounding region had responded on the USGS Did You Feel It? website.

History of strong earthquakes

Mexico is one of the most tectonically active countries in the world, and it experiences frequent significant earthquakes. This earthquake is a reminder of the many seismic events that Mexico has experienced in the recent past.

The most recent significant earthquake to strike Oaxaca was a M-6.5 that struck on Tuesday, February 12, 2008.
The most recent significant earthquake to strike Mexico was a M-7.2 that struck in Baja California on Sunday, April 4, 2010. There were two confirmed fatalities and 233 injured in the Mexicali area.
In September 1985, an earthquake measuring 8.1 on the Richter scale and centered in the subduction zone off Acapulco killed more than 4,000 people in Mexico City, more than 300 kilometers away.

Did You Feel It? Individuals report on the intensity of shaking

Tectonics of this earthquake

The March 20, 2012 earthquake occurred as a result of thrust-faulting on or near the plate boundary interface between the Cocos and North America plates. The focal mechanism and depth of the earthquake are consistent with its occurrence on the subduction zone interface between these plates, approximately 100 km northeast of the Middle America Trench, where the Cocos plate begins its decent into the mantle beneath Mexico. In the region of this earthquake, the Cocos plate moves approximately northeastwards at a rate of 60 mm/yr.

For the most recent information on this earthquake, maps, and scientific and technical information, visit Magnitude 7.4 – Oaxaca, Mexico.

The March 11 Tohoku Earthquake, One Year Later. What Have We Learned?

Aqsa Ahmed — Fri, 09 Mar 2012 12:00:46 +0000

March 11, 2011

The ground in Japan began rumbling March 9, 2011, with a series of large foreshocks measuring over magnitude 6 and peaking at magnitude 7.2. But it was not until two days later that the main event, which would trigger the tsunami responsible for the bulk of the destruction, occurred. At magnitude 9.0, the massive earthquake is world’s fifth largest earthquake since 1900. In Japan, it is the largest since modern instrumental recordings began 130 years ago. The tsunami even caused over $50 million in damage to nearly two dozen harbors in California.

Strong shaking lasted three to five minutes in some places. The tsunami damaged the Fukushima I Nuclear Power Plant, disabling the emergency generators needed to cool reactors and leading to nuclear meltdowns and radiation leaks. William Ellsworth, of the USGS Earthquake Science Center in Menlo Park, Calif., says photos and video of the tsunami will provide powerful evidence of the implications of hazard risk around the globe. “I no longer need to explain to anyone the power of, or danger posed by, a tsunami,” he said.

This USGS ShakeMap shows shaking intensity along the east coast of Japan during the March 11 magnitude 9.0 earthquake.

In the United States, scientists and staff at the USGS’s National Earthquake Information Center, which monitors all significant global earthquakes, began working around the clock as the Tohoku earthquake and its resulting tsunami occurred. They quickly produced products for emergency responders, the public, the media, and the academic community about the earthquake’s potential impact and damages, as well as provided scientific background for the interpretation of the event’s tectonic context and potential for future hazards.

When the shaking and tsunami subsided, they left staggering destruction behind. Japan reported around 20,000 casualties, making the event the 20^th most deadly earthquake and tsunami in the past 100 years. In addition, the country experienced $200-300 billion in property and infrastructure losses, an economic toll that will affect Japan for years to come.

Experts note, however, that most of the losses were caused not by the quake itself, but by the unexpectedly large tsunami. They estimate that fewer than 5 percent of the damage came from the earthquake, due to Japan’s investment in infrastructure, engineering, and preparedness. Engineered buildings performed well under the high shaking levels, and the Japanese Earthquake Early Warning system provided up to 90 seconds’ warning of the earthquake for some residents in Tokyo.

Lessons from Tohoku

Altough the Tohoku quake did not occur in the United States or its territories, it was one of the most thoroughly recorded seismic events of its magnitude and provides valuable information to U.S. scientists seeking to understand how similar events would affect this Nation.

Tom Brocher, center director for the USGS Earthquake Science Center in Menlo Park, said, “The investment by the Japanese government in earthquake monitoring instrumentation yielded an unprecedented scientific and engineering data bonanza that will help the Japanese to mitigate damage from future earthquakes.”

For example, these data mean that scientists now know more about the probability of similar earthquakes and the potential size of their resulting tsunamis. An unparalleled amount of strong ground motion data were recorded that will help reduce uncertainty in seismic hazard assessments in Japan and elsewhere.

Researchers also know more about the effects of such earthquakes. For example, many cases of liquefaction were witnessed and filmed for the first time. Liquefaction occurs when soil loses strength and stiffness due to an applied stress like an earthquake and behaves like a liquid, often causing damage to structures and infrastructure.

Seismologists across the globe were surprised by the magnitude of shaking that occurred in the segment of fault responsible for the Tohoku quake. Japanese scientists had not believed a quake of such intensity could occur in that area, which in turn impacted tsunami strength estimates. According to Brocher, the tsunami defenses in the area were built in the event of a tsunami resulting from a magnitude 8.0 earthquake, not a 9.0.

This USGS ShakeMap shows projected shaking along the West Coast in the event of a magnitude 9.0 earthquake occurring along the Cascadia Subduction Zone.

Thus, even though the Japanese had planned and were well-prepared for a 200- or 300-year tsunami, they were not prepared for the 1000-year tsunami (an event that’s likely to occur just once every 1,000 years) that came instead. Consequently, Japan is currently updating its tsunami disaster plans for all of its coastal areas and requiring that all plans take evidence from paleo-tsunami deposits into consideration.

Paleo-tsunami deposits are the sand and mud that tsunamis leave behind. By studying deposits from recent events like the March 11 tsunamis, scientists are able to develop criteria for what those deposits look like and use them to examine coastal areas for records of tsunamis that struck centuries back. They can tell when tsunamis occurred and how far inland they reached by looking at the evidence left behind.

USGS coastal and marine geologists Bruce Jaffe, Bruce Richmond, and Rick Wilson have worked with Japanese scientists over the past year to study these deposits in Japan. Said Jaffe, “Japan has learned from this tsunami that it’s necessary to look at the geologic evidence for tsunamis in conjunction with the current understanding of earthquake potential to accurately assess the future tsunami hazard.” He explained that “Each tsunami brings its own sand and mud. Japan recognizes the value of using the very rich record of past tsunamis to help us understand the hazard for future tsunamis.”

The United States is also conducting its own paleo-tsunami deposit studies in California, Alaska, the Caribbean, Puerto Rico, and the Virgin Islands to better understand the tsunami risk in those areas.

This image shows fish and mud deposited from the tsunami on the road ringing Kawaihae Harbor in Hawaii on Saturday, March 12, 2011, at approximately 02:00 p.m. HST.

In the United States, the USGS and other seismologists are using data gained from Tohoku to better understand and update information on hazards along the Alaska-Aleutian and the Cascadia Subduction Zones, which slant beneath and can affect Alaska, British Columbia, Washington, Oregon, and Northern California. According to Brocher, the Tohoku earthquake had similar characteristics to those that might be expected of giant earthquakes in these subduction zones, which are the points where one tectonic plate moves under another.

Insights gained from the Tohoku earthquake are leading scientists to re-evaluate the way they’ve assumed many other major faults are segmented. This may end up altering some hazard analyses for the West Coast, and will contribute to improved scenario modeling, building code development, and public warnings about tsunami threats.

Moving Forward: The Work Continues in the United States

This 2008 USGS National Seismic Hazard Map shows projected earthquake intensity across the United States, including Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. . Information from these maps is used in building codes, insurance rate structures, risk assessments, and other public policy.

As part of the multi-agency National Earthquake Hazards Reduction ProgramtheUSGS Earthquake Hazards Program has the lead Federal responsibility to notify the public when earthquakes happen in order to enhance public safety and reduce losses through effective forecasts based on the best possible scientific information.

The USGS also monitors seismic activity throughout the Nation in a constant effort to understand what causes shaking, where it will occur, and how it will impact society.

We cannot predict earthquakes, and we cannot prevent them, but we can arm ourselves with information that helps us prepare for them and mitigate damage. As Ross Stein, a USGS geophysicist, said, “Earthquakes are part of our past. They’re part of our future. We will try our best, knowing what we are up against.”

Learn more about USGS research on earthquake hazards.