Stories tagged Earth Structure and Processes

Feb
08
2012

The Jurassic is a geologic time period of the Mesozoic Era that extends from 199.6± 0.6 Million years ago (Mya) to 145.5± 4 Mya, or from the end of the Triassic Period to the beginning of the Creataceous Period. Scientists from the University of Bristol have examined a katydid fossil from the Jiulongshan Formation (also known as the Haifanggou Formation, dated to be approxiamately 165 million years old) from Shantou Township, Ningcheng County, Inner Mongolia, China, and were able to recreate a sound made by these now extinct insects.

Like some amphibians, katydids (also known as bushcrickets) produce loud sounds by stridulation (rubbing certain body parts together). Mating calls from katydids are produced by rubbing a row of teeth on one wing against a plectrum on the other wing. What that song sounded like was unknown – until now.

Chinese palaeontologists, including Jun-Jie Gu and Professor Dong Ren from the Capital Normal University in Beijing, contacted Dr. Fernando Montealegre-Zapata and Professor Daniel Robert of Bristol's School of Biological Sciences. Dr. Michael Engel of the University of Kansas, a leading expert on insect evolution, also joined the team of reseachers.The Chinese palaeontologists produced a katydid fossil from the Jiulongshan Formation. The stridulating organs of the extinct katydid's wings were well preserved, and the Bristol researchers compared the anatomical construction to 59 living bushcricket species.They concluded that this animal must have produced musical songs.

Male katydids produced a single tone to serenade females. Using biomechanical principles, Dr. Montealegre-Zapata could reconstruct the song made by these insects. A video recording those sounds can be downloaded from the hyperlink below:
https://fluff.bris.ac.uk/fluff/u/inxhj/fqxIALCbZk8r_RBMfny__QRy/Video_S1...

Research article: Wing stridulation in a Jurassic katydid (Insecta, Orthoptera) produced low-pitched musical calls to attract females

Dec
08
2011

Sonar study location along the Tonga Trench
Sonar study location along the Tonga TrenchCourtesy NOAA (with adaptation by author)
Here’s something you don’t see everyday: some very amazing images of a chain of mountains heading toward a subduction zone in the South Pacific. (Make sure you watch the video at the top of this story link - it seems to take a few seconds to load). The pictures were unveiled this week at the annual American Geophysical Union meeting held in San Francisco, California.

Researchers from Oxford and Durham universities took sonar readings along the bottom of the South Pacific northeast of New Zealand that show a chain of underwater mountains being dragged westward on the Pacific plate and subducted into theTonga Trench . This chasm is second only to the Marianas Trench in seabed depth – nearly 11 kilometers (6.6 miles) deep. The computer model created from the data shows one giant volcano at the very edge of the trench breaking into huge blocks and beginning to collapse into the abyss. It’s actually pretty cool to see. Earthquakes occur less frequently near where the volcanoes are being gobbled up, and scientists differ on whether the giant broken chunks of the volcano help or hinder the subduction process, but the images clearly show the mechanism at work.

Illustration of plate boundaries and subduction
Illustration of plate boundaries and subductionCourtesy USGS
According to the theory of plate tectonics both oceanic crust and continental crust ride atop rigid plates that migrate slowly across the globe, colliding with and pulling away from each other. There are three main types of boundary zones created by this movement: convergent (moving toward each other), divergent (moving away from each other) and transform (moving side by side). In the first example, which is the type this article deals with, the lighter oceanic plate (Pacific Plate) is subducting under the heavier continental plate (Indo-Australian Plate). The process is part of the creation and recycling of the Earth’s lithosphere – that is it’s rocky crust along with the uppermost part of the mantle. Some mantle material is forced upward in the process, and the land near these subduction zones – like that in Japan and along the coast of Chile in South America - is often populated with volcanoes. This collision of plates causes tremendous tensions to build up along the contact zone. The extreme pressure can continue building over hundreds or even thousands of years until it's too much, and the plates start to shift. All the pent-up energy is suddenly released in fits and starts in the form of earthquakes and aftershocks, as happened this year (and is still happening) in Sendai, Japan and Christchurch, New Zealand.

The underwater volcanic chain spreads across the ocean bottom in a southeasterly direction for several thousands kilometers as each mountain makes it way westward toward the trench at the rate of about 6cm per year. That's about as fast as your fingernails grow in two months. The sonar images were taken at a depth of six kilometers below the ocean surface as part of a project funded by Australia’s Natural Environment Research Council (NERC) to help determine if the massive debris from the crumbling volcanoes have any effect on the frequency of earthquakes and tsunamis in the area.

SOURCE
BBC report

Nov
22
2011

Sakurajima is a stratovolcano and former island, now connected to the mainland. It is part of the Kirishima-Yaku National Park, and its lava flows are a major tourist attraction. Sakurajima volcano has frequently produced eruption plumes with significant visible electrical discharges (volcanic lightning). Its eruption in 1914 was the most powerful in 20th-century Japan. Eruptions from Sakurajima have also affected air traffic from the airport in the nearest city, Kagoshima. Large lapilli has broken the windshields of planes on several occasions, although no major incident has occurred.

The eruption at 1min 20 sec is particularly interesting.

See video

Nov
16
2011

If you look at the U.S. Nuclear Regulatory Commission’s interactive map of nuclear power plants in the United States, you will see several in states bordering the Atlantic Ocean. This prompted the Nuclear Regulatory Commission to request the U.S. Geological Survey (USGS), along with other governmental and academic partners, to research the potential for tsunamis to strike the U.S. Atlantic and Gulf of Mexico coasts, and prepare maps using sonar (originally an acronym for SOund Navigation And Ranging). Note that the March 11, 2011 earthquake near Honshu, Japan, created a tsunami that resulted in a nuclear disaster that is still being remediated.

NOAA Research Ship Nancy Foster: Nancy Foster supports applied research primarily for NOAA's National Ocean Service and Office of Oceanic and Atmospheric Research.
NOAA Research Ship Nancy Foster: Nancy Foster supports applied research primarily for NOAA's National Ocean Service and Office of Oceanic and Atmospheric Research.Courtesy National Oceanic and Atmospheric Administration
Through this research, initiated about five years ago, the leading potential source of dangerous tsunamis to the East Coast was identified as landslides, either originating in submarine canyons or on the continental slope of the submerged margin of the continent of North America.

According to USGS marine geologist Jason Chaytor, many years of data collection and integration of existing data sets was needed in order to produce seafloor maps with the resolution needed to identify all of the relevant features for this study. The first field effort of this project was a multibeam bathymetric mapping cruise conducted aboard the National Oceanic and Atmospheric Administration (NOAA) Ship Nancy Foster from June 4 to June 16, 2011. Using echosounders installed on the hull of Nancy Foster, the science team mapped canyons and shelf regions at high resolution over more than 380 square miles (1,000 square kilometers) of seafloor from south of Cape Hatteras, located offshore of North Carolina, to the eastern tip of Long Island in New York.
Bathymetric Map of Continental Slope 150 km Southeast of New Jersey: High-resolution multibeam bathymetry collected in and between Baltimore and Accomac Canyons during the June 2011 cruise. Color key at left shows depths (in meters).
Bathymetric Map of Continental Slope 150 km Southeast of New Jersey: High-resolution multibeam bathymetry collected in and between Baltimore and Accomac Canyons during the June 2011 cruise. Color key at left shows depths (in meters).Courtesy United States Geological Survey


A number of submarine landslides, some previously unknown, were either partly or completely mapped. Characteristics collected include the size and number of landslides, soil and rock properties, the water depth they occur in, and the style in which they fail. This information is often used in numerical modeling of tsunamis generated by landslides.

The scientists detailed their findings in the September/October issue of the USGS newsletter Sound Waves.

Nov
11
2011

On November 10, 2011, at 17:25 UTC (or 11:25am Central Standard Time), a shallow quake occured in Greece about 11.8 miles NE of the town of Patras. According to the European-Mediterranean Seismological Centre, this earthquake had a magnitude of 5.1 (later downgraded to a 4.6) and was a relatively shallow quake at 5 km (approximately 3.1 miles) below the Earth's surface.

This region is characterized by a high level of seismicity, and small tremors are continually recorded along the coast of Patras. Another interesting aspect of Patras is that in antiquity, there was an ancient oracle, over a sacred spring, dedicated to the goddess Demeter. Professor Iain Stewart from the University of Plymouth has been studying a supposed link between ancient. sacred places in Greece and Turkey and seismic fault lines. Many ancient temples and cities lie along those fault lines and this may not be merely due to chance, but they may have been placed there deliberately.The Temple of Apollo at Delphi with Mount Parnassus in the Background
The Temple of Apollo at Delphi with Mount Parnassus in the BackgroundCourtesy Wikimedia Commons

For example, the Oracle at Delphi has been given a geological explanation. The Delphi Fault (running east-west) and the Kerna Fault (running SE-NW) intersect near the oracular chamber in the Temple of Apollo. In that area, bituminous limestone (i.e. limestone containing bitumen, a tarlike deriviative of petroleum) has a petrochemical content as high as 20%. Analysis of spring water in the area showed the presence of hydrocarbon gases, such as ethylene. Geologists have hypothesized that friction from fault movement heats the limestone, causing the petrochemicals within to vaporize. It has been suggested that exposure to low levels of the sweet-smelling gas ethylene would induce a trance, or euphoric state. Could the naturally occuring ethylene account for the strange, prophetic behavior of the Pythia (the priestess at the Temple of Apollo)?

The Delphi research is certainly persuasive, and received favorable coverage in the popular press and Scientific American, but it has come under criticism. Critics argue that the concentrations of ethylene identified by the researchers would not be sufficient to induce a trance-like state, and thus the connection to the mantic behavior of the Pythia is dubious.

Report: Geomythology: Geological Origins of Myths and Legends
Article: Breaking the Vapour Barrier: What Made the Delphic Oracle Work?
Report: Oracle at Delphi May Have Been Inhaling Ethylene Gas Fumes

Related Report: Earthquake Faulting at Ancient Cnidus, SW Turkey

Oct
28
2011

What do a banana and a chunk of coal have in common? Carbon!

Dr. Peter Griffith, Director of NASA's Carbon Cycle and Ecosystems office, spoke to twenty of us training to be Earth Ambassadors for NASA about why it's important to teach people about the way carbon moves around on our planet, in order to help them understand climate change.

He showed us this fantastic video that describes the Carbon Cycle on earth and describes how "young, fast carbon" like that in a banana differs from "old, slow" carbon, like that in coal and other fossil fuels.

See video

Dr. Griffith also described how you can tell the difference between objects containing old carbon and young carbon by looking at the radioactive decay of carbon 14. Carbon in its normal state is called carbon 12, or C12. However, cosmic rays, like those from the sun, convert some atmospheric carbon into a slightly radioactive form called carbon 14, or C14. Over time, this carbon decays back into Carbon 12.

All living plants and animals contain some C14, since they constantly take in atmospheric carbon dioxide.

Fossil fuels like coal and oil, which have been underground for millions of years, contain only C12 (fully decayed Carbon,) while a banana still contains some C14 from atmospheric carbon dioxide the banana tree absorbed.

It is not surprising that the carbon downwind of power plants burning coal is mostly C12. Trees can also lock up carbon in their trunks and branches in for many years.

The carbon released by burning fossil fuels and setting tropical forests ablaze is carbon that would naturally have remained "locked" up. Human activities like these are creating an excess of long-lived carbon dioxide gas in the atmosphere and are causing our world's climate to warm.

NASA and other scientists are working hard to study the science of climate change. How our planet and its inhabitants will respond to the challenges resulting from this change remains to be seen.

Oct
27
2011

Servicio Nacional de Geología y Minería (SERNAGEOMIN) raised the alert status for the Cerro Hudson volcano in southern Chile recently. The Chilean government reported that before this morning nearly 900 volcanic earthquakes were noticed, most of which were not felt by residents living in the area. 119 people are currently evacuated from the Lake Caro area, and authorities are trying to evacuate another 13 individuals.

There are now three steam vents on the volcano, one of which is also emitting ash. Some photos taken from a recent flyby of the volcano can be seen here.

The ice-filled caldera (10-km-wide, or ~ 6.2 miles) of the Cerro Hudson volcano was not recognized until its first 20th-century eruption in 1971. Cerro Hudson is the southernmost volcano in the Chilean Andes related to subduction of the Nazca plate beneath the South American plate, and is 280 km (~ 174 miles) east of the Nazca-Antarctic-South American triple junction. An eruption about 6700 years ago was one of the largest known in the southern Andes during the Holocene, and a 1991 eruption was Chile’s second largest of the 20th century.

News report: Hudson Volcano forces evacuations in Southern Chile
Eruptions blogpost: Alert Status Raised to Red at Chile’s Hudson

See video

Oct
06
2011

[SETTING: Ted and Lily are in line at the cafeteria.]

Ted: [Leans over a little, like he’s sharing a secret.] I just heard from SAHRA that the National Science Foundation is funding another Critical Zone Observatory at the University of Arizona. That’ll make six CZOs.

Lily: [Shocked.] Sounds serious!

Ted: Well, yeah. I mean, the critical zone is basically the area along the Earth’s surface between the treetops aboveground and the groundwater table belowground. That’s where we do our day-to-day living and a lot of really important life-sustaining natural processes happen, like water and nutrient cycling.
Variety is the spice of life
Variety is the spice of lifeCourtesy cafemama

Lily: I was talking about Sarah. Who’s she?

Ted: [The miscommunication dawns on him.] Not Sarah, SAHRA. The Sustainability of semi-Arid Hydrology and Riparian Areas. They’re a Science and Technology Center based at the University of Arizona.

Lily: [Relieved.] Oh. Gotcha. Back to the Important Area Thingamabob. It sounds like a really big area with a whole lot going on. How’s anyone going to observe it?

Ted: You’re right. The critical zone is a massive area and studying it is daunting, but the NSF’s got something going on with these CZOs.

Lily: [Slightly annoyed.] Please chew with your mouth closed. You’re getting alphabet soup all over my shirt.

Ted: [Indignant.] What? Just ‘cause you can’t swim in my alphabet soup…

[Lily glares at Ted.]

Ted: [Sheepish.] Anyway, I was saying about how the Observatories are intended to be a resource for international collaborations between science disciplines. You know, interdisciplinary, multi-disciplinary, and such. This will allow scientists from geology, ecology, hydrology, etc to work together so we can understand how all the components interact in the Critical Zone.

Lily: Ah-ha! So the Observatories are like a potluck. Everyone brings their specialty to the table to make a whole meal.

Ted: Sure. And the best potlucks happen when lots of people bring something to share and there’s a variety of deliciousness.

Know what else? Each of the six Observatories is located in a different climate. More variety! By comparing the same processes in different climates, scientists will be better able to figure out how the critical zone will change under climate change.
Lily and Ted: On the set
Lily and Ted: On the setCourtesy pchow98

Lily: Huh. I had no idea that science news could make me so hungry.

Ted: Did you even hear what I just said?

Lily: [Mumbles to herself.] Where do you suppose I can get a recipe for tater tot hot dish? [To Ted.] Wait… whatdidjasay?

Ted: [Sighs.] Nevermind. I’m going to get some chocolate pudding. Want some?

Oct
05
2011

You are Cordially Invited

Publication Party, Public Reading, and Book Signing Event

for
FOOL ME TWICE: Fighting the Assault on Science in America
by
SHAWN LAWRENCE OTTO

Introduction by Don Shelby
Emcee Jim Lenfestey

"A gripping analysis of America's anti-science crisis."
Starred Kirkus Review
“In this incredible book, Otto explores the devaluation of science in America.”
Starred Publishers Weekly Review

You know you want to read it. Click here for more info
You know you want to read it. Click here for more infoCourtesy Shawn Lawerence Otto

Tuesday October 18, 2011 at 7PM
Target Performance Hall, Open Book
1011 Washington Avenue South, Minneapolis
(click here for directions and free parking)
This event is free and open to the public

sponsored by
the Loft Literary Center
the Science Museum of Minnesota

no reservation required, but click here to RSVP to help us plan

Beer, wine and light refreshments served
Books for sale at the event
Free book by drawing. To qualify: A) post about the event on Facebook B) tweet at the event with hashtag #FoolMeTwice and mention @ShawnOtto

Sep
20
2011

There’s been some buzz about the relationship between clouds and climate recently, prompting Andrew Revkin of the New York Times’ Dot Earth blog to get his panties in a twist about the “…over-interpretation of a couple of [scientific] papers…”

What gives? I wanted to know too, so I’ve done a bit – ok, a lot – of research and this is what I can tell you: The heart of the discussion is not whether there is a cloud-climate connection (that’s clear), but rather over what that relationship behaves like. There are at least three possible theories, but before we get to those, let’s review some important background concepts.

Gimme the Basics First

Cloud Formation

First, scientists think of air as units of volume called air masses. Each air mass is identified by its temperature and moisture content. Clouds are basically wet air masses that form when rising air masses expand and cool, causing the moisture in the air to condense. You can see the process in action yourself just by exhaling outside on a cool morning. The Center for Multiscale Modeling of Atmospheric Processes has a webpage to answer your other questions about clouds.

Earth’s Energy Budget
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow).  Outgoing energy is radiated (red).  The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.
Earth's energy budget: Incoming solar energy is either absorbed (orange) or reflected (yellow). Outgoing energy is radiated (red). The arrows show the direction and magnitude of movement where thick arrows signify bigger movements.Courtesy NASA

Energy from the Sun is essential for life on Earth. Let’s pretend the Earth has an “energy budget” where solar energy is like money, absorption is like a deposit, reflection is like a transfer, and radiation is like a withdrawal. It’s not a perfect analogy, but it’ll work for starters: Most of the incoming solar energy (money) is absorbed by (deposited into) the ocean and earth surface, but some is absorbed or reflected (transferred) by the atmosphere and clouds. Most of the outgoing energy is radiated (withdrawn) to space from the atmosphere and clouds. The figure to the right illustrates this process.

The Greenhouse Effect

Thanks to the greenhouse effect, our planet is warm enough to live on. The greenhouse effect occurs within the earth’s energy budget when some of the heat radiating (withdrawing… remember our budget analogy from above?) from the ocean and earth surface is reflected (transferred) back to Earth by greenhouse gases in the atmosphere. Greenhouse gases include carbon dioxide, methane, and water vapor. This National Geographic interactive website entertains the concept.

Climate Change

Climate change is occurring largely because humans are adding more greenhouse gases to the atmosphere. More greenhouse gases in the atmosphere means more heat reflected back to earth and warmer temperatures. Warmer temperatures might sound pretty good to your right now (especially if you live in Minnesota and could see your breath this morning as you walked to school or work), but it’s not. Why? Check out NASA’s really great website on the effects of climate change.

Alright, already. What’s the climate-cloud relationship?

From what I can tell, there are three possible theories about the climate-cloud relationship:

  • Clouds actively drive climate change. This is a linear process where clouds reflect too much heat back to Earth, which increases the average global temperature and causes climate change.
  • Clouds passively blunt climate change. This is a cyclical process where more climate change includes increasing average global temperature, which increases average global evaporation, which creates more clouds. More clouds absorb more heat, keeping the average global temperature from rising even faster and lessening climate change. This slows down (note: it does not stop) the rate of climate change.
  • Clouds passively amplify climate change. This is a cyclical process where more climate change includes increasing the average global temperature, which increases average global evaporation, which creates more clouds. More clouds reflect more heat back to Earth, which raises the average global temperatures and worsens climate change. This speeds up the rate of climate change.
  • So which is it? Probably NOT Theory #1. Maybe Theory #2… or maybe it’s Theory #3? Scientists aren’t quite sure yet, so neither am I, but the evidence is stacking against Theory #1 leaving two possible options. The next big question seems to be surrounding the size of the effects of Theory #2 and Theory #3.

    Using what you just read about cloud formation, the earth’s energy budget, greenhouse gases, and climate change (Woah. You just learned a lot!), what do you think? What’s the climate-cloud relationship?

    If you want, you can read more about what scientists are saying about the climate-cloud relationship here: