A West Coast Shake Up Call

Los Angeles Seismograph 7:10 AM EST – Credit ABC TV7

 

# 6780

 

Residents in Southern California and the Baja Peninsula were on the receiving end of a significant seismic shock overnight, as a 6.3 temblor struck 160 miles off the coast at 2:36 am (local time).

 

No tsunami was generated, and no warnings went out from the Pacific Tsunami Warning Center. Light to moderate shaking (Max CDI=V) was reported in San Diego and Ensenada according to the USGS.

 

There were originally reports of a second 6.1 shock, but that may have been a false reading as it no longer appears on the USGS earthquake feed.

The epicenters of these quakes were well off shore, and not along the famous San Andreas Fault which runs through much of California.

 

The USGS posted this Tectonic Summary.

 

The December 14, 2012 M 6.3 earthquake 250 km southwest of Avalon, California occurred as a result of shallow normal faulting within the oceanic lithosphere of the Pacific plate. This event is located some 400-450 km west-southwest of the plate boundary between the Pacific and North America plates – the San Andreas fault system in southern California – and is not associated with that fault system.

Instead, this earthquake represents intraplate faulting along northeast-southwest trending normal faults within the crust of the Pacific plate, just to the west of California’s continental shelf. The causative fault is not known at this time. At the location of this event, the Pacific plate moves to the northwest with respect to the North America plate at a velocity of approximately 54 mm/yr.

While the broad region surrounding the December 14, 2012 event experiences frequent earthquakes along the San Andreas and associated faults in southern California, the area offshore and within 250 km of this earthquake has not hosted any events greater than M 6 over the past 40 years. The largest nearby earthquake was a M 5.1 event 200 km to the northeast in June of 2004, 80 km west of the border between the US and Baja California. A M 3.3 earthquake struck approximately 35 km to the northeast in April 1981, representing the closest event in the USGS earthquake catalog.

 

While this morning’s wake up calls are unlikely to have caused any significant damage, they are a reminder that much of California (along with much of the world) is seismically active.

 

In 2010 (see Revised Risk Of `The Big One’ Along San Andreas Fault) scientists using better tools and techniques, determined that big earthquakes occur far more frequently along the San Andreas fault than was previously believed.

 

Major quakes have occurred – on average – every 88 years along the southern section of this fault line, or three times more frequently than prior estimates.

 

Which makes southern California long overdue for `the big one’.

 

Shakeout.org, which promotes yearly earthquake drills and education around the country, has been a leader in earthquake preparedness in California. 

 

And the county of Los Angeles – recognizing the many natural disaster threats that face their residents – has produced an excellent L. A. County Emergency Survival Guide.

Well worth downloading, and using, no matter where you live.

 

To become better prepared as an individual, family, business owner, or community to deal with these types of disasters, I would invite you visit the following preparedness sites.

 

FEMA http://www.fema.gov/index.shtm

READY.GOV http://www.ready.gov/

AMERICAN RED CROSS http://www.redcross.org/

And finally, some of my own preparedness articles include:

 

When 72 Hours Isn’t Enough

In An Emergency, Who Has Your Back?

An Appropriate Level Of Preparedness

The Gift of Preparedness 2012

»» Read More

USGS: Eastern Earthquakes - Rare But Powerful

Map shows earthquakes (circles) greater than magnitude 3.0 since 1974 plotted on the 2008 USGS National Seismic Hazard Map for the central and eastern United States. Warmer colors on this map indicate areas of higher hazard. Larger earthquakes are represented by larger circles.

# 6700

 

 

Although big earthquakes are rare in the Eastern United States, historic accounts have suggested that when they occur the shock waves are felt much farther away from the epicenter than with earthquakes in places like California.

 

The Charleston earthquake of 1886, which was estimated to be between a 6.6 and a 7.3 magnitude, was reportedly felt (cite) as far away as Boston, Massachusetts, Milwaukee, Wisconsin, Chicago, Illinois, Cuba and Bermuda.

 

The 1811-12 New Madrid earthquakes were reportedly felt over much of the Eastern United States, with the USGS reporting that:

• People were awakened by the shaking in New York City, Washington, D.C., and Charleston, South Carolina.

 

Although this phenomenon has been talked about for years, direct measurements of a relatively large east coast seismic event have been lacking due to their relative rarity. 

 

All that changed last year when a 5.8 quake struck central Virginia.

 

The following shake map from the USGS shows the areas reporting shaking from two recent quakes, a 6.0 in Central California, and the recent 5.8 Virginia quake. By an incredibly large margin, the smaller eastern quake was felt over a much bigger area.

 

 

For more on this phenomenon, the USGS has details on a study, that is slated to be published next month in the Bulletin of the Seismological Society of America.

 

New Evidence Shows Power of East Coast Earthquakes Virginia Earthquake Triggered Landslides at Great Distances

Released: 11/6/2012 8:30:00 AM

Earthquake shaking in the eastern United States can travel much farther and cause damage over larger areas than previously thought.

 

U.S. Geological Survey scientists found that last year's magnitude 5.8 earthquake in Virginia triggered landslides at distances four times farther—and over an area 20 times larger—than previous research has shown.

 

"We used landslides as an example and direct physical evidence to see how far-reaching shaking from east coast earthquakes could be," said Randall Jibson, USGS scientist and lead author of this study. "Not every earthquake will trigger landslides, but we can use landslide distributions to estimate characteristics of earthquake energy and how far regional ground shaking could occur."

 

"Scientists are confirming with empirical data what more than 50 million people in the eastern U.S. experienced firsthand: this was one powerful earthquake," said USGS Director Marcia McNutt. "Calibrating the distance over which landslides occur may also help us reach back into the geologic record to look for evidence of past history of major earthquakes from the Virginia seismic zone."

 

This study will help inform earthquake hazard and risk assessments as well as emergency preparedness, whether for landslides or other earthquake effects.

 

This study also supports existing research showing that although earthquakes are less frequent in the East, their damaging effects can extend over a much larger area as compared to the western United States.

 

The research is being presented today at the Geological Society of America conference, and will be published in the December 2012 issue of the Bulletin of the Seismological Society of America.

(Continue . . . )

 

 

People who live on, or near, major fault lines are usually cognizant of the dangers, although not everyone is prepared to meet them. Those of us who live away from these seismic zones rarely give earthquakes much of a thought.  

 

But this study shows that a large eastern U.S. quake - even one that occurs several hundred miles away - can be felt, and potentially do structural damage.

 

Just as you don’t have to live on the coastline to be impacted by a hurricane, you don’t have to live on a fault line to be hit by an earthquake. 

 

Which is why emergency officials urge that while it is important to identify probably threats in your area, you really need to adopt an `All hazards’ approach to preparing.  You really can’t know if the next disaster to strike will be a tornado out of the sky, a shift in the earth’s crust, or a massive winter storm.

 

 

For more on how to prepare against `All Hazards', including those you may not automatically assume are a threat where you live, you should visit the following sites:

 

FEMA http://www.fema.gov/index.shtm

READY.GOV http://www.ready.gov/

AMERICAN RED CROSS http://www.redcross.org/

 

And lastly, you may wish to revisit some of my preparedness essays, including:

 

In An Emergency, Who Has Your Back?

An Appropriate Level Of Preparedness

NPM11: Are You Earthquake Prepared?

»» Read More

Shaken, And Hopefully Stirred

Location of last weekend’s Earthquake - USGS

 

# 6691

 

The 7.7 quake last weekend (see Haida Gwaii Quake & Tsunami Advisories) off the northern coast of British Columbia was a not-so-gentle reminder that the Pacific Northwest is not immune to strong earthquakes.

 

While the San Andreas fault in Southern California is better known, the Cascadia fault that runs along the Northern California, Oregon, Washington, and B.C. coast (well south of last week’s quake) is believed capable of generating a massive earthquake/tsunami combination, much like we saw with Japan’s Great Earthquake of 2011.

 

Based primarily on the fact that it’s happened before.

 

Last year, in Just A Matter Of Time, I described how records showed that 312 years ago an orphan tsunami struck the coast of Japan, without an accompanying earth tremor being felt.

 

It’s origin remained a mystery for years, but today scientists - looking at sediment levels and tree growth rings – can easily see evidence of a great quake (8.7-9.2)  occurring along the Cascadia fault at that time.

 

 

Although at the time of my previous blog there was evidence of a series of major quakes along this fault line, going back thousands of years, in August of 2012 a new study was published that suggests another quake is `overdue’.

 

The study, was published by the USGS, and may be read at the link below:

 

Turbidite Event History—Methods and Implications for Holocene Paleoseismicity of the Cascadia Subduction Zone

By Chris Goldfinger, C. Hans Nelson, Ann E. Morey, Joel E. Johnson, Jason R. Patton, Eugene Karabanov, Julia Gutiérrez-Pastor, Andrew T. Eriksson, Eulàlia Gràcia, Gita Dunhill, Randolph J. Enkin, Audrey Dallimore, and Tracy Vallier

 

 

For those who would prefer not to wade through the paper, we have a press release from the Oregon State University, that explains the findings.  Excerpts follow:

 

13-year Cascadia study complete – and earthquake risk looms large

8-1-12

CORVALLIS, Ore. – A comprehensive analysis of the Cascadia Subduction Zone off the Pacific Northwest coast confirms that the region has had numerous earthquakes over the past 10,000 years, and suggests that the southern Oregon coast may be most vulnerable based on recurrence frequency.

 

Written by researchers at Oregon State University, and published online by the U.S. Geological Survey, the study concludes that there is a 40 percent chance of a major earthquake in the Coos Bay, Ore., region during the next 50 years. And that earthquake could approach the intensity of the Tohoku quake that devastated Japan in March of 2011.

 

“The southern margin of Cascadia has a much higher recurrence level for major earthquakes than the northern end and, frankly, it is overdue for a rupture,” said Chris Goldfinger, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences and lead author of the study. “That doesn’t mean that an earthquake couldn’t strike first along the northern half, from Newport, Ore., to Vancouver Island.

 

“But major earthquakes tend to strike more frequently along the southern end – every 240 years or so – and it has been longer than that since it last happened,” Goldfinger added. “The probability for an earthquake on the southern part of the fault is more than double that of the northern end.”

 

The publication of the peer-reviewed analysis may do more than raise awareness of earthquake hazards and risks, experts say. The actuarial table and history of earthquake strength and frequency may eventually lead to an update in the state’s building codes.

(Continue . . . )

 

 

Since we can’t prevent earthquakes, and accurate prediction of when they will occur is beyond our technology, our only recourse is to prepare for them.

 

In January of 2011 I profiled a Washington state based preparedness educator Carol Dunn, who maintains an excellent website on the hazards faced by those living in the Pacific Northwest called 2Resilience.

 

You’ll find numerous resources geared for professional first responders, citizen volunteers, and families, individuals, and businesses looking to improve their level of knowledge and preparedness.

 

Many of us who follow @Caroldn on Twitter find her dedication and enthusiasm on preparedness issues to be quite contagious.  And if your interests lie in that direction I’d certainly recommend you include her feed.

 

Another resource I strongly recommend is Shakeout.org, which promotes yearly earthquake drills and education around the country.

 

For more on how you can prepare for `the big one’ (even if you live someplace other than Los Angeles), I would recommend you download, read, and implement the advice provided by the The L. A. County Emergency Survival Guide.

 

And to become better prepared as an individual, family, business owner, or community to deal with these types of disasters: visit the following preparedness sites.

 

FEMA http://www.fema.gov/index.shtm

READY.GOV http://www.ready.gov/

AMERICAN RED CROSS http://www.redcross.org/

 

Because no matter where you live, its just a matter of time before the next disaster strikes.

»» Read More

7.1 Magnitude Earthquake Strikes Columbia

 

USGS Real time earthquake monitor

 

NOTE:  USGS now shows the quake to be a 7.3 mag

# 6598

 

A 7.1 magnitude quake struck the southeastern region of Columbia around 12:31 pm EST (16:31 UTC) today - roughly 61km (38mi) SSE of Popayan, Colombia – the capital of of the Columbian department of Cauca, with a population of roughly 250,000 people.

 

The USGS shakemap indicates moderate shaking could have been expected in Popayan and surrounding communities.  This was a deep quake (162 km), and so that may have substantially lessened its impact.

 

 

 

We’ve no word on damage, or injuries as yet. 

The Pacific Tsunami Warning Center has issued a statement saying:

TSUNAMI INFORMATION STATEMENT NUMBER 1 NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI 639 AM HST SUN SEP 30 2012

EVALUATION BASED ON ALL AVAILABLE DATA A DESTRUCTIVE PACIFIC-WIDE TSUNAMI IS NOT EXPECTED AND THERE IS NO TSUNAMI THREAT TO HAWAII. REPEAT. A DESTRUCTIVE PACIFIC-WIDE TSUNAMI IS NOT EXPECTED AND THERE IS NO TSUNAMI THREAT TO HAWAII. THIS WILL BE THE ONLY STATEMENT ISSUED FOR THIS EVENT UNLESS ADDITIONAL DATA ARE RECEIVED

»» Read More

USGS: New Real-Time Earthquake Map

 

New Real-Time USGS Earthquake Map

 

# 6289

 

 

The USGS has introduced an impressive real-time earthquake map on their Earthquakes Hazards Webpage, that allows the user to customize how the data is delivered. 

 

The control panel (see below) allows the user to filter out quakes based on minimum display parameters.

 

 

And the map has the ability to pan and zoom, allowing the user to drill down to the local level (including information on cities, streets, and fault lines).

Close up View of seismic activity around Tokyo, Japan

 

The global map display lists the most recent earthquakes (based on your criteria), and you can click on each event to get more information.

 

 

 

For more on the unveiling of this new tool, we have the following press release from the USGS.

 

Enhanced Real-time Earthquake Information Now Online

Released: 4/17/2012 1:53:48 PM

 

New U.S. Geological Survey webpages featuring more robust, real-time earthquake information are now available.  Whether the earthquake is minor or major, earthquake.usgs.gov visitors will see a unique, interactive earthquake map that regularly updates, can be individually tailored, and provides saved settings for future map visits.

 

In 2011, the website logged almost 48 million unique visitors and nearly 468 million pageviews.

 

"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 webpages supply 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, users can access Latest Earthquakes  to zoom into and pan the world map to select different basemaps, as well as overlays such as plate boundaries, faults, and earthquake hazards. Information can be fine-tuned to display earthquakes on the map by time window, magnitude, depth, and maximum recorded intensity.  A list below the map updates for the current map view and settings and is sortable by any data column. Users can also download earthquake lists into other map interfaces like GoogleEarth (KML format) and Excel (CSV).

 

The event page when an earthquake is selected has also been upgraded and it provides interactive features and more information, including downloadable data files in various formats for each earthquake product, such as ShakeMap, Did You Feel It?, etc. This new event-centric view allows the visitor 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 utilize the same user interface to search a comprehensive earthquake catalog populated with all existing USGS earthquake data, presenting a seamless view of recorded world-wide earthquakes current and historic.  It is anticipated that this product will be released in beta later this year.

»» Read More

USGS: Spate of Large Earthquakes Not Related

 

# 5948

 

 

Since 2004 the earth has seen an increase in the number of extremely large earthquakes (over the numbers recorded in the previous hundred years) which has led some people to wonder if they might be connected, or part of a pattern.

 

The chart below, from the USGS, shows twelve  8.0 magnitude or greater quakes since 2004, or about 50% more than would normally be expected.

 

 

This pattern has led to a great deal of speculation – particularly on the internet - that we have entered an `age of earthquakes’.

 

The USGS posted a short analysis – based on a recently published paper in the GRL (Geophysical Research Letters)- that states that this rise in seismic activity in within the range that one might expect from pure chance.

 

First the USGS statement, then a link to the article.

Spate of Large Earthquakes Not Related

Released: 11/7/2011 4:00:00 PM

MENLO PARK, Calif. – The magnitude-7.2 earthquake on October 23^rd in Turkey and the magnitude-9.0 quake that impacted Japan in March are leading many to wonder if these events are part of a larger global trend toward giant earthquakes. After combing through 110 years’ worth of global seismic records, USGS seismologist Dr. Andrew Michael concluded that the recent increase in the number of large earthquakes may just reflect random occurrence.

 

Using three distinct statistical tests, Dr. Michael studied whether variations in the number of large, global earthquakes could be explained as a random fluctuation, once local aftershocks of the large earthquakes are taken into account. In a recently published paper, he explains how he tested whether the intervals between earthquakes have followed a clustering pattern that would be suggestive of quakes related to each other. He then developed a specific earthquake-triggering statistical model to determine if global seismicity increased after the largest earthquakes, examining the effect of the largest earthquakes on smaller ones. Finally, he tested for clustering in the energy released by earthquakes.

 

In each test, he found that the apparent clustering among large earthquakes can be described as a random fluctuation and cannot be used to predict future events.

 

"Large earthquakes, in statistical terms, do not happen very often, even though they are noteworthy for their enormous consequences. In events that do not happen very often, random processes are highly variable and may appear clustered even if they are not," said Dr. Michael. "While the probability of future large mainshocks has not increased, neither has it decreased."

 

Dr. Michael concludes that global forecasts of earthquakes and the damage they inflict should use the longest possible historical record, rather than just the record from the recent past.

 

"This research is a good example of how science can empower our decisions with knowledge rather than fear," said USGS Director Marcia McNutt. "Those who live in earthquake country should work to make their surroundings as safe as possible and know what to do if an earthquake happens regardless of how quiescent or active the rest of the planet may be."

 

The paper "Random variability explains apparent global clustering of large earthquakes" appears in Geophysical Research Letters, a publication of the American Geophysical Union, and is available upon request.

 

The abstract to the article in the GRL may be accessed at the link below:

 

GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L21301, 5 PP., 2011
doi:10.1029/2011GL049443

Random variability explains apparent global clustering of large earthquakes

key Points

• Large global earthquakes are temporally random plus aftershocks
• Apparent global clustering proposed by others is due to random variability
• Current risk of future earthquakes is not elevated except for local aftershocks

Andrew J. Michael

U.S. Geological Survey, Menlo Park, California, USA

 

The bottom line, according to the author:

 

Except for regional aftershocks, which may occur for months or years after a major quake, recent earthquake activity is not a good predictor of the future.

 

Areas that have been seismically quiet for decades can suddenly, and without warning, experience a strong quake.

 

Which is why FEMA, READY.GOV, and other agencies continue to urge everyone to be prepared for all types of emergencies, including earthquakes.

 

Everyone needs an appropriate disaster plan, just as everyone should have a good first aid kit, a `bug-out bag’, and sufficient emergency supplies to last a bare minimum of 72 hours.

 

For more on  disaster preparedness, I would invite you to visit Ready.gov or revisit these blogs:

 

When 72 Hours Isn’t Enough

The L. A. County Emergency Survival Guide

An Appropriate Level Of Preparedness

 

And  reminder that early next year, two regions will be holding major earthquake exercises.

 

The Great Central U.S. Shakeout On February 7, 2012

The Great Utah ShakeOut, April 17, 2012

»» Read More

USGS Statement On The Virginia Earthquake

 

 

# 5778

 

Yesterday’s 5.8 earthquake which rocked much of the eastern United States is a reminder that while rare, earthquakes can and do occur in the eastern half of the country. 

 

Below you’ll find an earthquake hazard map from FEMA’s website covering the central and eastern United States.

 

The colors in the map reflect “seismic design categories” (SDCs), which anticipates the likely intensity of seismic shaking in a region.

 

As you can see, the New Madrid region in Missouri, Tennessee, and Arkansas is considered at highest risk, but the coastal region of South Carolina is also at risk from strong earthquakes.

 

The USGS issued a statement last night on the Virginia quake, with an explanation on why the quake was so widely felt, and a request for `shake reports’ from residents who felt the quake.

 

Magnitude-5.8 Earthquake Strikes National Capital Area

Released: 8/23/2011 6:43:31 PM

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communications and Publishing
12201 Sunrise Valley Dr, MS 119
Reston, VA 20192
National Earthquake Information Center 
Phone: 303-273-8500

A magnitude 5.8 earthquake struck the National Capital Area on Tuesday, August 23, at 1:51p.m. (EDT), causing moderate shaking and potentially significant damage, and was felt throughout Northern Virginia and neighboring areas. No casualties are expected.

 

The earthquake occurred near Louisa and Mineral, Va., approximately 100 miles southwest of Washington, DC. It was a shallow earthquake, and shaking was recorded all along the Appalachians, from Georgia to New England.

 

There have been several aftershocks.

 

The information provided by the USGS is part of a government-wide response effort, in coordination with the Department of the Interior, the Department of Homeland Security, and the White House.

 

The earthquake occurred in the Central Virginia Seismic Zone, which has produced earthquakes in the past. The most notable was an earthquake that occurred in 1875 that scientists believe was about a magnitude 4.5.

 

This earthquake is almost as strong as the strongest recorded earthquake in Virginia, a magnitude 5.9, which occurred in May 1897 in Giles County, Va. The strongest recorded earthquake to strike the East Coast was the 1886 Charleston, S.C., earthquake, which was about a magnitude 7.3.

 

Those who felt the earthquake can go online and report their observations on the USGS Did You Feel It? website. Over 10,000 reports of felt shaking have already been received from more than 3400 zip codes all over the eastern United States.

 

The earthquake was felt so widely because it was a shallow earthquake, and geologic conditions in the eastern U.S. allow the effects of earthquakes to propagate and spread much more efficiently than in the western United States.

 

Western rock is relatively young, which means it absorbs a lot of the shaking caused by earthquakes. Thus, western earthquakes result in intense shaking close to the epicenter, but fade more quickly the farther the earthquakes travel.

 

In the eastern United States, on the other hand, the rock is far older, and so earthquakes can have a much larger and more widespread impact. Earthquake energy can therefore spread farther and have a greater impact.

 

Earthquakes cannot be predicted. Although earthquakes are more commonly associated with the western United States, there have been significant earthquakes in the East too. Scientists cannot predict the timing of specific earthquakes. However, families and communities can improve their safety and reduce their losses by taking actions to make their homes, places of work, schools and businesses as earthquake-safe as possible. The USGS provides information on how you can prepare at the Earthquake Hazards Program Website.

 

For more information on this earthquake, please visit the PAGER reading here.

 

For more information on earthquake and other hazards, please visit the USGS Natural Hazards website. The USGS operates a 24/7 National Earthquake Information Center in Golden, Colo., that can be reached for more information at (303) 273-8500.

»» Read More

Statement From FEMA Spokesperson On East Coast Earthquake

 

 

 

# 5776

 

USGS Community Internet Intensity Map

If you felt the earthquake, report it to the USGS.  It will help with their analysis. Use their Did You Feel It? — Tell Us ! web page.

 

This statement was issued by the Ready Campaign at 4:02 pm EST today, in the wake of the 5.9 earthquake that was felt across much of the Eastern United States.

 

 

Statement from FEMA Spokesperson Rachel Racusen on Earthquake

Ready Campaign sent this bulletin at 08/23/2011 04:02 PM EDT

WASHINGTON-Federal Emergency Management Agency Spokesperson Rachel Racusen issued the following statement on the earthquake that impacted the mid Atlantic Region and other states today:

 

"According to United States Geological Survey (USGS), the mid Atlantic Region of the United States experienced a 5.9 magnitude earthquake. FEMA, along with the entire federal family, is closely monitoring the situation and is in close contact and coordination with our partners in the National Capital Region and our state partners. Though there are no early reports of major damage or requests for assistance at this time, preliminary damage assessments are currently taking place in all affected states and we will continue to work closely with their emergency management officials.

 

"Due to overload of cell phone usage, there are reports of cell phone congestion.  We request that members of the public use email or text messages if possible to communicate for the next few hours, except in cases of emergency, so that emergency officials can continue to receive and respond to urgent calls. We encourage everyone in the affected areas to listen to the direction of their local officials. More information will be provided as it becomes available."

FEMA's Ready.gov website offers guidance on what to do to stay safe in the event of an earthquake. Click here for more information.

 

Follow FEMA online at http://blog.fema.gov, www.twitter.com/fema , www.facebook.com/fema , and www.youtube.com/fema .  Also, follow Administrator Craig Fugate's activities at www.twitter.com/craigatfema . 

(continue . . . )

»» Read More

5.9 Earthquake Rocks Virginia & D.C.

 

 

Updated

 

# 5776

 

An unusually strong and shallow earthquake struck central Virginia this afternoon, with a preliminary magnitude of 5.9.  It was reportedly felt as far west as Ohio, as far north as New Hampshire, and as far south as Atlanta.

 

While damage reports are yet to come in, media is reporting that JFK airport in New York has been shut down, and the Pentagon has been evacuated.

USATODAY has a running news list on this breaking story:

5.9 magnitude quake rocks East Coast

 

 

Photo Credits USGS

 

 

While large earthquakes in the eastern half of the country are relatively uncommon, they do happen.  This appears to be the largest quake in Virginia since the May 31st, 1897 quake in Giles County, Va.

 

And of course Charleston, S.C. was devastated by a 7.3 magnitude quake in 1886.

 

USGS map

As you can see by the map above, most of the United States is seismically active – with Alaska, Hawaii, the west coast, and the mid-west seeing the most – and strongest, quakes.

 

Few places, however, can claim to be completely immune to quakes.

 

Even in Florida, which is about as seismically quiet as it comes – we’ve recorded quakes.   And of course, quakes in the Gulf of Mexico, Atlantic, or Caribbean are even capable of sending Tsunami’s our way. 

 

For information on how to prepare for an earthquake, you may wish to revisit a few of my earlier blogs on seismic risks:

 

Because It Can Happen Here

Planning To Survive

Shaken And (Hopefully) Stirred

»» Read More

Borne In The USA

 

 

# 5745

 

 

After a unusually quiet first six months of the year – no doubt influenced by the prolonged drought across much of the southern tier of states – mosquito borne threats like Dengue fever and West Nile Virus (WNV) are back in the news again.

 

Last year, you may recall, was a banner year for arboviral disease in the United States (see MMWR: Arboviral Disease Surveillance – 2010) with more than 1,000 cases of West Nile Virus reported.

 

Other viral players included California serogroup viruses (CALV), eastern equine encephalitis virus (EEEV),  St. Louis encephalitis virus (SLEV) and Powassan virus (POWV).

 

As for Dengue fever - Florida recorded a total of 63 locally-acquired cases, and an epidemic in Puerto Rico produced more than 20,000 cases and 31 deaths.

 

While we aren’t seeing those kinds of numbers this year, the rains have recently returned to Florida and other parts of the southland, and so the number of mosquito borne illnesses has begun to rise.

 

A few reports:

 

Our first stop is Martin County, on the lower S.E. coast of Florida, where a case of imported Dengue fever may have led to a locally acquired infection.

 

This is from an announcement by the Martin County Health Department.

 

MARTIN COUNTY HEALTH DEPARTMENT ISSUES HEALTH ADVISORY REGARDING MOSQUITO-BORNE DISEASE

August 9th, 2011

The Martin County Health Department is urging residents to take precautions against mosquito borne illness following a confirmed case of dengue fever. The illness was acquired by a resident of the Rocky Point section of Port Salerno following a recent trip to a Caribbean island. The Health Department is also awaiting test results on a possible second case of the illness in the same household.

(Continue . . . )

 

As of August 6th, Florida’s Arbovirus Surveillance System has reported 10 cases of imported Dengue fever from travelers returning from countries where that virus is endemic. Additionally, 51 cases of imported Malaria have been reported in Florida as well.

 

Similarly, Marion County Florida released a statement yesterday regarding an imported case of Dengue, saying:

 

This is Marion County’s first case of dengue fever this year. The case of dengue fever was contracted
outside of the U.S., but because dengue fever can be transmitted to another human from a mosquito that has bitten a person with the disease, citizens should take every precaution to protect themselves from mosquito bites

 

Next stop is Duval County (Jacksonville) Florida, where over the past two weeks at least 8 cases of West Nile Virus have been reported.  This from the Duval County Health Department.

 

DCHD MOSQUITO-BORNE ILLNESS ALERT

The Duval County Health Department (DCHD) continues its mosquito-borne illness alert for Duval County. Additional human cases of West Nile Virus (WNV) have been confirmed. The most recent cases involve a 38 year-old male and 57 and 38 year-old females. Duval County has eight confirmed cases of WNV in 2011.

 

Lest anyone think that mosquito borne illnesses are only a Florida problem, yesterday Mississippi reported their first WNV fatality of the year, and their 13th known infection (AP article State reports first West Nile virus death of year).

 

Additionally, human infections with WNV have been reported this year in New Jersey, Virginia, California, Arizona, Texas, Colorado, Louisiana, Georgia, North Dakota, South Dakota, and Wyoming.

 

As the MMWR report on West Nile last week stated:

 

Detection and reporting are incomplete, leading to a substantial underestimate of the actual number of cases. Based on previous studies, for every case of WNV neuroinvasive disease, approximately 140 human WNV infections occur, with 80% of infected persons remaining asymptomatic and 20% developing nonneuroinvasive disease

 

 

The USGS maintains series of interactive disease maps showing the confirmed vector-borne illness reports around the country, along with reports of mosquito, bird, sentinel, and veterinary surveillance. 

 

 

Reports, as you might expect, can often lag a few weeks behind the current situation. Laboratory tests take time, and there are sometimes other delays in reporting.

 

With the summer rise in mosquito populations, public health departments are urging people to become more diligent about removing breeding places for mosquitoes around their homes.

 

But it isn’t just outside the home where people need to check . . .  some mosquito species are perfectly capable of setting up light housekeeping inside the home as well.

 

While the Aedes aegypti is most commonly associated with spreading disease, the Aedes albopictus or `Asian tiger’ mosquito is quite capable of doing so as well.

 

Aedes Albopictus Photo Credit CDC PHIL

 

The Asian Tiger mosquito has made extensive inroads around the world over the past 40 years, and is considered one of the top 100 worst invasive species according to the Global Invasive Species Database.

 

And unlike its aegypti cousin, the albopictus is also a daytime biter, and can often be found inside the home breeding in flower vases, potted plants, toilets, and neglected swimming pools.

 

 

Dark Blue indicates the A. Albopictus native range, while green indicates new introductions in last 40 years.

Although mosquitoes are pretty much ubiquitous here in Florida, as well as in and many other areas, one shouldn’t panic over being bitten.

 

The vast majority of mosquitoes here in the US are not carrying infectious diseases.

 

The odds of contracting West Nile Virus, Dengue, EEE, or any of the mosquito borne encephalitis viruses are actually pretty small.

 

In order to vector a disease, they first must bite a host(bird, animal, or human) that is viremic – infected and with sufficient viral material in their bloodstream.

 

Still, it only makes sense to take precautions.

 

Like wearing DEET when you are outdoors, wearing long sleeves and pants, and removing breeding places inside and outside of your home.

 

Any container of water . . .  even as small as a bottle cap . . . can breed mosquitoes.  Containers with houseplants appear to be particularly good homes for these pests.

 

For more details on mosquito precautions visit the Florida DOH Mosquito-borne Disease Prevention webpage or the CDC’s  FIGHT THE BITE page.

»» Read More

USGS: Distant Earthquakes Can Trigger Fault `Creep’

 

 

 

# 5547

 

(Credit USGS)

 

 

A little over a month ago in Divining Japan’s Seismic Future I wrote about an article that appeared in the April 9th edition of the  International Business Times, called:

 

Japan warns of massive earthquake and volcanic explosion after the April 7 earthquake

 

You can follow the link and read the (short) article, but the gist of the story is that the massive March 11th earthquake and subsequent aftershocks may have increased the stress on adjacent fault lines and nearby volcanoes, increasing the risks of additional seismic events including volcanic eruptions.

 

The idea that a large earthquake in one part of the world might trigger additional earthquakes (or volcanic eruptions) someplace far away – days, weeks, or even months later - is a controversial one.

 

Can a large earthquake put new stresses on distant (or even adjacent) fault lines, setting them up to fracture sooner rather than later?

 

In doing some research on the matter last month, I found the USGS in their FAQ About Relationships Between Earthquakes and Volcanic Eruptions - Is there a relationship between earthquakes larger than magnitude 6 that occur along major fault zones and nearby volcanic eruptions? stated, in part:

 

After large earthquakes the question of whether such strong events can trigger nearby volcanic eruptions often comes up.  The short answer to this question is: “not very often.”

 

There are a few examples in the historical record that suggest a connection between large earthquakes and volcanic eruptions, but even these, on close inspection, do not show a simple causative relationship

This FAQ goes on to provide some examples of possible seismic events that may have been triggered by large nearby earthquakes. So while saying it doesn’t happen often, this FAQ isn’t completely dismissive of notion of large earthquakes acting as volcanic triggers.

 

In Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance  Silke Eggert and Thomas R. Walter provide a litany suspected seismic trigger events, including:

 

A well-known sequence occurred in South America wherein the volcanoes Cordón Caulle and Puyehue erupted in Chile just one day after the large 1960 Valdivia earthquake (Barrientos, 1994; Lara et al., 2004).

 

Other prominent examples of volcanoes that have been active in association with major tectonic earthquakes are Mount Vesuvius and Mount Etna in Italy (Sharp et al., 1981).

 

 

Fast forward a month and in a somewhat related story, yesterday the USGS posted a press release regarding a study that appears this week in Nature Geoscience.

 

 

Triggered creep as a possible mechanism for delayed dynamic triggering of tremor and earthquakes

David R. Shelly, Zhigang Peng, David P. Hill & Chastity Aiken

 

Here, as the press release explains, scientists looked at the effects of distant earthquakes (as small as 5.4 magnitude) on the San Andreas fault in California.

 

They found that even moderate seismic waves passing through the fault line can induce delayed tremors that may persist for days.  Tremors they believe signify slow-motion fault slippage, that could potentially alter the timing of the next quake on that fault.

 

This from the USGS Newsroom.

 

 

Distant Earthquakes Can Trigger Deep Slow Fault Slip

Released: 5/9/2011 5:12:12 PM

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192
Leslie Gordon
Phone: 650-793-1534

 

MENLO PARK, Calif. — Researchers examining the San Andreas Fault in central California have found evidence that distant earthquakes can trigger episodes of accelerated (but still very slow) slip motion, deep on the fault.

 

While a sudden slip on a fault generates earthquakes capable of strong shaking, a fault can also slip slowly. Sometimes, these slow movements on a fault, known as creep events, are accompanied by a weak ground vibration known as a tectonic tremor, which can be detected on sensitive seismometers.

 

Using data from these seismometers, researchers from the U.S. Geological Survey and Georgia Institute of Technology examined the locations and timing of tremor activity following large distant earthquakes. In some cases, they found evidence that triggered slip and its associated tremor migrated along the length of the fault, and persisted long after the passage of seismic waves from the distant earthquake. The scientists hypothesize that distant earthquakes can act as a trigger for ongoing episodic creep events, sometimes altering their timing.

 

The researchers also noted that creep events in other locations can sometimes trigger earthquakes. While they caution that their study was focused on triggered tremor rather than triggered earthquakes, they suggest that prolonged triggered creep episodes could be relevant for both phenomena. In particular, triggered creep episodes could provide a physical explanation for the time delay commonly observed between passing seismic waves and distantly generated earthquakes.

 

Published online this week in the journal, “Nature Geoscience,” the study, “Triggered creep as a possible mechanism for delayed dynamic triggering of tremor and earthquakes,” is the latest of ongoing research on the effects of large earthquakes on distant faults.

 

While distantly triggered small earthquakes are relatively common, another recent study found no evidence for distantly triggered large earthquakes, at least during the first few days after a large event. The current study provides a possible mechanism to explain a range of time delays between a large distant event and triggered earthquakes.

 

 

The `money quote’ here appears to be near the end, which I’ve bolded. 

 

While a large earthquake in Japan or Indonesia may not  trigger contemporaneous large earthquakes elsewhere in the world, the evidence suggests that they may have a long-term delayed effect on distant fault lines.

 

Last month, in UNDP: Supercities At Seismic Risk, I wrote about a study that claimed that half of the world’s supercities (pop. 2-15 million) were located in high seismic regions.  

 

Which makes research like this - that increases our understanding of the dangers of future earthquakes - not only interesting, but vitally important as well.

»» Read More

USGS: Central U.S. Earthquake Preparedness Handbook

 

 

 

# 5527

 

With the Great Central U.S. Shakeout drill scheduled for later this morning, today is a good day to promote the new and revised Central U.S. Earthquake Handbook provided by the USGS.

 

 

Here is the press release, followed by a link to the (large & graphic intensive) PDF file.

 

NOTE: I experienced some difficulties viewing this PDF in my (firefox/Foxit reader) browser, and had to save it to my desktop before viewing.

 

 

Preparing for the Great ShakeOut Drill: Handbook Offers Vital Earthquake History and Preparedness Information to Central U.S. Residents

Released: 4/27/2011 5:48:44 PM

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192

The U.S. Geological Survey (USGS) encourages people to join the millions in 11 states who have signed up to participate in the April 28, 2011, Great Central U.S. ShakeOut drill. The upcoming 200^th anniversary of the New Madrid earthquakes is an opportune time to consider earthquake preparedness and learn about the region’s earthquake history. Go to the ShakeOut website to sign up for the drill, learn preparedness tips and learn how to “Drop, Cover and Hold On” during an earthquake.

 

A newly released handbook from the USGS can assist with preparing for earthquakes in the central United States. “Putting Down Roots in Earthquake Country – Your Handbook for Earthquakes in the Central United States” provides detailed information about the threat of earthquakes in this part of the country, particularly along the New Madrid and Wabash Valley seismic zones.

 

"Everyone has an individual responsibility for earthquake safety, but you're also part of a bigger community," said USGS Director Marcia McNutt. "In addition to saving lives, the goal of this drill is to help develop resilient communities that can recover more quickly after natural disasters.  I encourage you to learn what steps you can take to help the places you live and work ride out the next earthquake with minimal impact."

(Continue . . . )

 

 

Putting Down Roots in Earthquake Country—Your Handbook for Earthquakes in the Central United States

U.S. Geological Survey contributors: Richard Dart, Jill McCarthy, Natasha McCallister, and Robert A. Williams

 

 

 

 

 

 

 

 

This handbook provides information to residents of the Central United States about the threat of earthquakes in that area, particularly along the New Madrid seismic zone, and explains how to prepare for, survive, and recover from such events. It explains the need for concern about earthquakes for those residents and describes what one can expect during and after an earthquake.

 

Much is known about the threat of earthquakes in the Central United States, including where they are likely to occur and what can be done to reduce losses from future earthquakes, but not enough has been done to prepare for future earthquakes. The handbook describes such preparations that can be taken by individual residents before an earthquake to be safe and protect property.

 

 

For more on the seismic threat in the central United States, and today’s Shakeout drill, you may wish to revisit:

 

NEPEC: New Madrid Earthquake Hazard Review

The Great Central U.S. Shakeout

The World Upside Down

»» Read More

USGS: 6.4 Aftershock Rattles Northern Japan

 

# 5446

 

 

 

The strongest aftershock since Wednesday struck northern Japan a short while ago (8:36 pm local time).

 

Local reports have listed the quake as a 6.2, but the USGS is currently showing it as a 6.4.  Magnitude readings are often changed as more data comes in.

 

While strong enough that buildings in Tokyo (nearly 400km to the south) reportedly swayed - no tsunami warning has been issued.

 

 

 

Magnitude 6.4 - NEAR THE EAST COAST OF HONSHU, JAPAN

2011 March 25 11:36:24 UTC

Location 38.763°N, 141.942°E

Depth   39.2 km (24.4 miles)

Region   NEAR THE EAST COAST OF HONSHU, JAPAN

Distances

• 108 km (67 miles) ENE (58°) from Sendai, Honshu, Japan
• 127 km (79 miles) SE (146°) from Morioka, Honshu, Japan
• 172 km (107 miles) NE (48°) from Fukushima, Honshu, Japan
• 395 km (246 miles) NNE (29°) from TOKYO, Japan

»» Read More

Study: The Role Of Migratory Birds In Spreading Bird Flu

 

 

# 5442

 

 

One of the more contentious debates in the world of avian influenza is over exactly what role migratory birds play in the spread of highly pathogenic H5N1.  

 

Bird enthusiasts and naturalists tend to point to the poorly regulated and controlled poultry trade as being the main source of the spread of the bird flu virus, while those in the poultry industry tend to blame migratory birds.

 

Over the years we’ve seen study after study that either implicates migratory birds in the spread of the virus, or minimizes their role.

 

 

Last September (see Another Migratory Bird Study) a paper appeared in the British Ecological Society's Journal of Applied Ecology, that claimed that the global spread of the H5N1 virus through migratory birds was possible . . . but unlikely.

 

In a blog from 2009, called  India: The Role Of Migratory Birds In Spreading Bird Flu  I wrote about an article entitled  Scientists rule out spreading of bird flu by migrant birds in India  from Xinhua News.

 

And in January of 2008, Reuters carried a report called:

 

Don't blame wild birds for H5N1 spread: expert

BANGKOK (Reuters) - There is no solid evidence that wild birds are to blame for the apparent spread of the H5N1 virus from Asia to parts of Europe, Africa and the Middle East, an animal disease expert said on Wednesday.

 

There was also no proof that wild birds were a reservoir for the H5N1 virus, Scott Newman, international wildlife coordinator for avian influenza at the U.N.'s Food and Agriculture Organization, said at a bird flu conference in Bangkok.

(Continue . . . )

 

 

Despite these statements to the contrary, there have been plenty of other reports that strongly associate migratory birds with the spread of the virus.

A few include:

 

Korea: Migratory Birds Behind Spread Of H5N1

EID Journal: H5N1 Branching Out

Japan: Hooded Crane Positive For H5N1

Not One Of The Usual Suspects

FAO: On The Trail Of Avian Influenza

 

 

Since I don’t have a bird in this fight, I readily concede that both are probably significant contributing factors in the spread of the virus.

 

I see no reason why they should be mutually exclusive.

 

Which brings us to a study that was recently published in PLoS One  called:

 

 

Wild Bird Migration across the Qinghai-Tibetan Plateau: A Transmission Route for Highly Pathogenic H5N1

Diann J. Prosser, Peng Cui, John Y. Takekawa, Mingjie Tang, Yuansheng Hou, Bridget M. Collins, Baoping Yan, Nichola J. Hill, Tianxian Li, Yongdong Li, Fumin Lei, Shan Guo, Zhi Xing, Yubang He, Yuanchun Zhou, David C. Douglas, William M. Perry, Scott H. Newman

Background

Qinghai Lake in central China has been at the center of debate on whether wild birds play a role in circulation of highly pathogenic avian influenza virus H5N1. In 2005, an unprecedented epizootic at Qinghai Lake killed more than 6000 migratory birds including over 3000 bar-headed geese (Anser indicus). H5N1 subsequently spread to Europe and Africa, and in following years has re-emerged in wild birds along the Central Asia flyway several times.

Methodology/Principal Findings

To better understand the potential involvement of wild birds in the spread of H5N1, we studied the movements of bar-headed geese marked with GPS satellite transmitters at Qinghai Lake in relation to virus outbreaks and disease risk factors.

 

We discovered a previously undocumented migratory pathway between Qinghai Lake and the Lhasa Valley of Tibet where 93% of the 29 marked geese overwintered. From 2003–2009, sixteen outbreaks in poultry or wild birds were confirmed on the Qinghai-Tibet Plateau, and the majority were located within the migratory pathway of the geese. Spatial and temporal concordance between goose movements and three potential H5N1 virus sources (poultry farms, a captive bar-headed goose facility, and H5N1 outbreak locations) indicated ample opportunities existed for virus spillover and infection of migratory geese on the wintering grounds.

 

Their potential as a vector of H5N1 was supported by rapid migration movements of some geese and genetic relatedness of H5N1 virus isolated from geese in Tibet and Qinghai Lake.

Conclusions/Significance

This is the first study to compare phylogenetics of the virus with spatial ecology of its host, and the combined results suggest that wild birds play a role in the spread of H5N1 in this region. However, the strength of the evidence would be improved with additional sequences from both poultry and wild birds on the Qinghai-Tibet Plateau where H5N1 has a clear stronghold.

(Continue . . . )

 

 

 

The USGS has released a press statement on this study, (which was funded by USGS, FAO, National Science Foundation and the Chinese Academy of Sciences) that describes the project and the results.

 

New research suggests wild birds may play a role in the spread of bird flu

LAUREL, Md. -- Wild migratory birds may indeed play a role in the spread of bird flu, also known as highly pathogenic avian influenza H5N1.

 

A study by the U.S. Geological Survey, the United Nations Food and Agriculture Organization and the Chinese Academy of Sciences used satellites, outbreak data and genetics to uncover an unknown link in Tibet among wild birds, poultry and the movement of the often-deadly virus.

 

Researchers attached GPS satellite transmitters to 29 bar-headed geese – a wild species that migrates across most of Asia and that died in the thousands in the 2005 bird flu outbreak in Qinghai Lake, China. GPS data showed that wild geese tagged at Qinghai Lake spend their winters in a region outside of Lhasa, the capitol of Tibet, near farms where H5N1 outbreaks have occurred in domestic geese and chickens.

 

This is the first evidence of a mechanism for transmission between domestic farms and wild birds, said Diann Prosser, a USGS biologist at the USGS Patuxent Wildlife Research Center. "Our research suggests initial outbreaks in poultry in winter, followed by outbreaks in wild birds in spring and in the breeding season. The telemetry data also show that during winter, wild geese use agricultural fields and wetlands near captive bar-headed geese and chicken farms where outbreaks have occurred."

(Continue . . . )

 

 

Like most scientific studies, this one increments our knowledge, rather than completing it.

 

While falling a bit short of finding a smoking gun, it documents a plausible mechanism for the H5N1 virus to be spread from domesticated poultry to wild birds during the winter, and from there relayed primarily by asymptomatic birds along the migratory pathways. 

The authors conclude by stating:

Our study identifies QHL and Lhasa as important linkages between wild and domestic transmission of H5N1 and provides new supporting information regarding the role of wild birds in long distance spread of this virus.

 

Further investigation of wild birds and H5N1 transmission within the Central Asian Flyway will increase our understanding of how wild birds may contribute to virus circulation and the unique pattern of outbreaks in this remote region.

»» Read More