From the University of Utah a press release with a shaky basis, since all hurricanes create some micro-seismicity. But, our friends will likely try to make something of it.
Superstorm Sandy shook the US
‘Standing waves’ in Atlantic caused seismicity as far as Seattle
SALT LAKE CITY, April 18, 2013 – When superstorm Sandy turned and took aim at New York City and Long Island last October, ocean waves hitting each other and the shore rattled the seafloor and much of the United States – shaking detected by seismometers across the country, University of Utah researchers found.
“We detected seismic waves created by the oceans waves both hitting the East Coast and smashing into each other,” with the most intense seismic activity recorded when Sandy turned toward Long Island, New York and New Jersey, says Keith Koper, director of the University of Utah Seismograph Stations.
“We were able to track the hurricane by looking at the ‘microseisms’ [relatively small seismic waves] generated by Sandy,” says Oner Sufri, a University of Utah geology and geophysics doctoral student and first author of the study with Koper. “As the storm turned west-northwest, the seismometers lit up.”
Sufri was scheduled to present the preliminary, unpublished findings in Salt Lake City Thursday, April 18 during the Seismological Society of America’s annual meeting.
There is no magnitude scale for the microseisms generated by Sandy, but Koper says they range from roughly 2 to 3 on a quake magnitude scale. The conversion is difficult because earthquakes pack a quick punch, while storms unleash their energy for many hours.
The shaking was caused partly by waves hitting the East Coast, but much more by waves colliding with other waves in the ocean, setting up “standing waves” that reach the seafloor and transmit energy to it, Sufri and Koper say.
While many people may not realize it, earthquakes are not the only events that generate seismic waves. So do mining and mine collapses; storm winds, waves and tornadoes; traffic, construction and other urban activities; and meteors hitting Earth.
“They are not earthquakes; they are seismic waves,” says Koper, a seismologist and associate professor of geology and geophysics. “Seismic waves can be created by a range of causes. … We have beautiful seismic records of the meteor that hit Russia. That’s not an earthquake, but it created ground motion.”
While Sandy’s seismicity may be news to many, Koper says microseisms just as strong were detected before and after the superstorm from North Pacific and North Atlantic storms that never hit land but created “serious ocean wave action.”
Koper adds: “Hurricane Katrina in 2005 was recorded by a seismic array in California, and they could track the path of the storm remotely using seismometers.”
In a related study set for presentation on Friday at the seismology meeting, Koper and geophysics undergraduate student YeouHui Wong found preliminary evidence that seismometers near Utah’s Great Salt Lake are picking up seismic waves generated either by waves or winds on the lake.
Koper says researchers wonder if microseisms from storms and other causes might trigger tiny but real earthquakes, but “that hasn’t been investigated yet,” he says.
Earthscope Picks up Seismic Waves from Ocean Wave Collisions
The microseisms generated by Sandy were detected by Earthscope, a National Science Foundation-funded array of about 500 portable seismometers that were first placed in California in 2004 and have been leapfrogging eastward so that most now are located east of line running from Minnesota to east Texas, and west of a line from Lake Erie to Florida. Some remain scattered across the Midwest and West, with a heavier concentration in the Pacific Northwest.
Earthscope’s purpose is to use seismic waves from quakes and other sources to make images of Earth’s crust and upper mantle beneath North America – similar to how X-rays are used to make CT scans of the human body. To do it accurately, scientists must understand all sources of seismic waves.
Sufri says the new study included Earthscope data from Oct. 18 to Nov. 3, 2012, “which coincides with the passage of Hurricane Sandy, and we tried to understand microseisms that were generated.”
Sandy caused a damaging storm surge due to its size – almost 1,100 miles in diameter for tropical-storm-force winds – more than its intensity, which was 3 when it hit Cuba and 2 off the Northeast coast.
“The energy generated by Sandy is going to be used to image the crust and upper mantle under North America,” says Koper, noting that Earthscope uses years of seismic data to construct images. “We are using seismic waves created by ocean waves to make images of the continent.”
Normal ocean waves “decay with depth very quickly,” says Koper. But when Sandy turned, there was a sudden increase in waves hitting waves to create “standing waves” like those created when you throw two pebbles in a pond and the ripples intersect. “Pressure generated by standing waves remains significant at the seafloor,” he says.
“When Sandy made that turn to the northwest, although wind speeds didn’t get dramatically bigger, the seismic energy that was created got tremendously bigger because the ocean’s standing waves were larger from the wave-wave interaction,” he adds.
Not only did the seismic waves become more energetic, “but the periods got longer so, in a sense, the sound of those seismic waves got deeper – less treble, more bass – as the storm turned,” Koper says.
Seismic Tracking of Hurricanes
Seismologists can track Sandy and other big storms because seismometers detect three components of motion: one vertical and two horizontal. If most of the energy on a seismometer is detected with a north-south motion, it means the source of the energy is north or south of the device.
“If you have enough seismometers, you can get enough data to get arrows to point at the source,” Koper says.
He says the seismologists didn’t track Sandy in real time, but the seismographic data of the storm suggests it might be possible to help track storms in the future using their seismicity.
Sufri speculates that seismic tracking of storms might allow observations that satellites can miss, and perhaps could help researchers “understand how climate is changing and how it is affecting our oceans – are we seeing more intense storms and increasing numbers of storms?”
Koper says the Sandy study “is exploratory science where we are trying to learn fundamental things about how the atmosphere, oceans and solid Earth interact.”
Video of seismic activity from superstorm Sandy may be viewed here:
The Seismological Society of America Salt Lake City meeting website, including study abstracts, is at: http://seismosoc.org/meetings/2013/
Related articles
- Superstorm Sandy literally shook the United States (rdmag.com)
- Superstorm Sandy shook the US (esciencenews.com)
- Superstorm Sandy shook the U. S., literally (sciencedaily.com)
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I would start with a “duh” of course a massive atmospheric event can cause vibrations on the crust. We all knew that already.
Why should we care about seismic tracking of hurricanes? Is there a shortage of satellites?
The last question about this causing earthquakes is so bogus and dumb, could they start by providing statistically relevant examples of post hurricanes quake?
This is the kind of bogus undergraduate paper I would write to get a pass mark, just word padding and a hell lot of “possible scenarios ” that never happened.
Without a comparison to the impact of other hurricanes, this particular study is worthless. And, according to the article they have seismic data on other storms but only address Sandy which tells me that Sandy wasn’t anything spectacular or they’d be trumpeting the comparisons.
Not part of the CISPA protest today then Anthony? Disappointing.
REPLY: First I’ve heard of it. I had to search for it to know what you are talking about.
http://thenextweb.com/insider/2013/04/22/anonymous-leads-200-websites-in-april-22-blackout-to-protest-cispa/
– Anthony
Living on the beach in Japan certainly gives one an interesting perspective on the power of mother nature in terms of earthquakes, typhoons and typhoon-induced seismic activity.
It also gives me a healthy respect for insurance companies and power companies as I see half my roof on top of my car following a massive typhoon or broken creature comforts and rolling blackouts following massive quakes.
It also creates severe eye-muscle fatigue from excessive eye rolling as I read “papers” (another word comes to mind) like this one tying desperately to tie earthquakes to CAGW….
Oh, the stupidity…. It hurts….
Somebody please make it stop!
“But, our friends will likely try to make something of it.”
My friends won’t make anything out of this at all. Now my enemies might try. But all it really is, is a testament to the sensitivity of modern equipment.
“caused seismicity”: I do laugh at the increasing use of abstract nouns. No longer do sports commentators say that Fred should run faster; nowadays Fred has to show increased pace.
Sounds incredible, and probably is.
The planet is constantly singing with seismicity so how these small swings could be detected in this noise I have no idea.
“there was a sudden increase in waves hitting waves to create “standing waves”” and “– less treble, more bass – ” is “too much for the body” as we literally say in Spain 😉
“The shaking was caused partly by waves hitting the East Coast, but much more by waves colliding with other waves in the ocean, setting up “standing waves” that reach the seafloor and transmit energy to it, Sufri and Koper say.”
A standing wave is a fixed wave pattern (hence the name!) They do not “collide” with anything and hence cannot cause seismic waves or similar.
This is probalby best charactered as “fundamental” since, as in the orginal of where if comes from.
. “Pressure generated by standing waves remains significant at the seafloor,” he says.
Which would be measureable with bottom pressure meter not a siesmograph. I guess he’s just not very good at expressing himself.
All this pressure has to be creating a whole lotta heat…
No doubt it’ll show up on the ARGO’s as an increase of .0000000nn Kelvin-Joule/nanometer/hour
(an as yet unused metric, awaiting licensing to Penn State’s Nobel Atmospheric Tree Ring Institute)
Class of 1980, College of Mines and Mineral Industries, Department of Geology and Geophysics.
These bozos have become a supreme embaressment to me.
One Bachelor’s in Geology, one in Geophysics, and I can outhink the entire department!
Mark H.
“There is no magnitude scale for the microseisms generated by Sandy, but Koper says they range from roughly 2 to 3 on a quake magnitude scale. The conversion is difficult because earthquakes pack a quick punch, while storms unleash their energy for many hours.”
If they are tracking ‘energy’ as this suggests, then the power of a 6-hour storm would have to be multiplied by 3600 to calculate the energy (energy = power * time) to be comparable in energy output to the power of a 6-second earthquake. If the storm has 1/3600th the power of a magnitude 2 earthquake, it’s equivalent Richter scale magnitude is NEGATIVE 1.5, as significant as a gnat’s hair.
for wws @ur momisugly 1:45 am.
You read my mind! Careful where you go in there; some parts may/will shock you.
Your comment refers to instrument sensitivity. I speculate the whole global warming cabal is caused by this change. Not very long ago temperture was measured in whole degrees; now in hundreths or even thousandths. The change gave desk bound “scientists” a whole new playground. Since warming is measured in [at most] tenths of a degree without more “precise” measurements the idiots would have nothing to rant about. Makes one wonder if global warming is just ” a tempest in a teapot”.
Ok. Now show us Katrina.
Seismicity?
Perhaps they really mean ‘sound waves’ also known as ‘vibrations’.
A far cry from a ‘shock wave’ and any seismic researcher guessing at total seismic power is a buffoon. Otherwise we’d hear terms like; “The magnitude 7.4 quake was followed quickly by 6.3 and 5.8 aftershocks, that adds up to a magnitude 19+ total destruction earth movement folks!”. Bogus!
Supposedly the Chinese were able to hear armies marching by listeners in specially dug pits. I guess they heard all of the seismic marches thundering.
Then I visualized watching a hurricane hit a coastline (three times in sixty years now). Waves are uncountable. There is no giant massive wave colliding with the shoreline or other waves; there are long discontinuous chains of waves peaking and rolling at different times along many miles of coast. Perhaps in a straight blow, waves might merge into massive waves as were described in ‘The Perfect Storm’ by the U.S. Coast Guard helicopter rescue teams, (supposedly 100 ft, (30.5 meters) from crest to trough). Otherwise, all the shaken stuff seems to be what’s left of some researchers mental components rattling around.
I love those parts about; “…Koper says researchers wonder if microseisms from storms and other causes might trigger tiny but real earthquakes, but “that hasn’t been investigated yet,” he says…”
and
“…The microseisms generated by Sandy were detected by Earthscope, a National Science Foundation-funded array of about 500 portable seismometers that were first placed in California in 2004 and have been leapfrogging eastward so that most now are located east of line running from Minnesota to east Texas…”
Oh!? NSF funded and the line of ‘portable’ seismometers manned by ‘students’?; manned meaning they dig them in, dig them out and collect the recordings. Plus a small alarm blurb about ‘triggering’ earthquakes needing investigation.
Translated as, “Give us more money!!”.
All I can say is, that if seismic centers were listening, all they heard was a long continuous mumble sound from a whole lotta shaking going on. Which means any USGS seismic center should be able to provide a graph of disturbances.
I can see how waves will shake the crust of the earth when there are seawalls in place now that were beaches and marsh land in the past. One video that was a good one to show the waves crashing on a seawall 3 hours before high tide and Sandy’s storm surge came ashore in union beach NJ.. Sick
Until the last bit where they try to tie the work in with climate change this was a good article on the sensitivity of modern seismic equipment. At least they ask if storms are getting more intense and we are seeing more of them rather than assuming they are. Maybe they see the writing on the wall that CAGW is loosing its credibility.
MJP
It is my understanding that a portion of the South African coastline has cliffs which, when the wind is just right, get pounded by waves creating seismic disturbances that can be detected almost anywhere in the world. It should be noted that the southern oceans are provide a very long reach which allows storms to generate very large waves.
A southern hemisphere storm even managed to reach far enough north to impact Long Beach.
http://journals.tdl.org/icce/index.php/icce/article/viewFile/927/024_Kaplan
“… Between April 20 and
24, 1930, prior to the construction of the Middle (Los Angeles-Long Beach) detached
breakwater, large waves entered the Bay and caused extensive damage to the
inner Long Beach breakwater (O’Brien, 1950). In 1939, waves of destructive amplitudes
caused great damage to the then partially completed detached breakwater and
some damage to the San Pedro breakwater. In the first case, the swell was engendered
by a southern hemisphere storm …”
I would imagine that tossing 10 ton boulders around would make the earth shake at least on a local basis.
Is this unprecedented? Sheesh!
“The shaking was caused partly by waves hitting the East Coast, but much more by waves colliding with other waves in the ocean, setting up “standing waves” that reach the seafloor and transmit energy to it, Sufri and Koper say.”
Waves do not “collide” on the open ocean. They pass through each other — that is, the force moving through the water one way is utterly uninhibited by the force through the water the other way. In an ocean wave the actual water does very little moving except for up and down in a basically circular fashion as an elementary school science experiment showed 45 years ago.
At most these “collisions” cause a bit of spray in the are and a piling up of the water in a temporary heap. The minimal amount of water that is piled up due to these waves would hardly amount to anything in terms of gravitational pull on the ocean floor. The spray of the waves would cause even less of a rumble. Utter rubbish.
correction: “spray in the air”
Surf-beat. We see it in generated on the continental shelf any times there are storms at sea. Move along…nothing to hear, here.
Hey! I left the College of Mines and Mineral Sciences in November 1980, didn’t get the dissertation approved until March 1982–very bad thing to leave loose ends like that. Glad to hear from a fellow Runnin’ Ute.
I think many of the comments above are overly harsh. I see nothing in the press release claiming that Sandy (or even Katrina) were “unprecedented” or even special. This reads to me as a straight-up report on the capability to detect and isolate the vibrations caused by ocean storms at continental distances and through bedrock. That’s a darned impressive capability. The fact that ocean waves create vibration in the earth is obvious but the fact that we can now detect them is amazing.
Previous seismic renderings of the earth’s core have been based on infrequent point sources of vibration. Either deliberate explosions set for the purpose or “natural experiments” such as analyzing the readings after an earthquake. The potential increase in frequency, area and resolution from being able to use mere storms as sources is significant.
And, no, I am not put off by the closing speculation about how this could “help researchers understand how climate is changing”. More relevant is the rest of the quote where the author asks neutrally “are we seeing more intense storms [or] increasing numbers of storms?” If this research enables another line of evidence that debunks the “extreme weather” myth, I’m all for it. And if, contrary to my hypothesis, the research shows that storms really are getting more severe, then we need to know that, too.