Though less frequent, earthquakes on the East Coast can typically be felt over a much larger area than those with a similar magnitude on the West Coast. The bedrock in California, for example, is fractured, causing seismic waves that travel through it to dissipate faster. In the eastern half of the United States, the bedrock is less fractured and stronger, allowing earthquake energy to travel farther. (via NYTimes)
Pop-upView Separately

Though less frequent, earthquakes on the East Coast can typically be felt over a much larger area than those with a similar magnitude on the West Coast. The bedrock in California, for example, is fractured, causing seismic waves that travel through it to dissipate faster. In the eastern half of the United States, the bedrock is less fractured and stronger, allowing earthquake energy to travel farther. (via NYTimes)

Fuente: The New York Times

Shishikura’s team took soil layer samples along the Tohoku coast and checked them against disaster accounts recorded in ancient chronicles. This helped them conclude that major temblors and tsunami repeatedly slam Tohoku over a cycle of between 500 and 1,000 years. Shishikura had planned to visit the Fukushima Prefectural Government last March 23 to explain this danger. Shishikura’s team even drew up maps of the areas flooded by the 869 tsunami and planned to distribute copies to residents along the coast. The maps turned out to be nearly identical to the areas that were inundated on March 11. “We could have saved some lives if the tsunami had come just a month later,” he lamented. (via The Japan Times Online)
View Separately

Shishikura’s team took soil layer samples along the Tohoku coast and checked them against disaster accounts recorded in ancient chronicles. This helped them conclude that major temblors and tsunami repeatedly slam Tohoku over a cycle of between 500 and 1,000 years. Shishikura had planned to visit the Fukushima Prefectural Government last March 23 to explain this danger. Shishikura’s team even drew up maps of the areas flooded by the 869 tsunami and planned to distribute copies to residents along the coast. The maps turned out to be nearly identical to the areas that were inundated on March 11. “We could have saved some lives if the tsunami had come just a month later,” he lamented. (via The Japan Times Online)

Fuente: japantimes.co.jp

As part of a project funded by the Southern California Earthquake Center, David Lynch (USGS), Kenneth Hudnut (USGS), David Dearborn (LLNL) and John Bayless (First Point Scientific Inc.) have made a number of low altitude photographic flights over the San Andreas Fault and parts of the Banning Fault. The goal is to obtain imagery with a spatial resolution of just a few centimeters on the ground; for planning field operations, to document the surface state of the fault before a major earthquake, and to provide many examples of fault landforms for education. (…) Together, they form a continuous record from the Salton Sea in Imperial County to central California, near California State Highway 198 in Monterey County. All photographs are in the public domain and can be used by anyone for any reason. Credit: David K. Lynch. (via EPOD)
Pop-upView Separately

As part of a project funded by the Southern California Earthquake Center, David Lynch (USGS), Kenneth Hudnut (USGS), David Dearborn (LLNL) and John Bayless (First Point Scientific Inc.) have made a number of low altitude photographic flights over the San Andreas Fault and parts of the Banning Fault. The goal is to obtain imagery with a spatial resolution of just a few centimeters on the ground; for planning field operations, to document the surface state of the fault before a major earthquake, and to provide many examples of fault landforms for education. (…) Together, they form a continuous record from the Salton Sea in Imperial County to central California, near California State Highway 198 in Monterey County. All photographs are in the public domain and can be used by anyone for any reason. Credit: David K. Lynch. (via EPOD)

Fuente: epod.usra.edu

Earthquakes - Shock Waves (by USGS)

Source: http://gallery.usgs.gov/videos/438. This short excerpt is from a USGS/Bay Area Earthquake Alliance produced television program “Shock Waves: 100 Years After the 1906 Earthquake”. This specific segment describes some of the history behind our modern understanding of the earthquake process. The program received numerous industry awards and was nominated for a regional Emmy Award in the Bay area. It aired twice on KPIX CBS5 and its affiliate station around the time of the April 18, 2006, 100 year anniversary of the Great San Francisco Earthquake. The full program is streamed at the link:http://earthquake.usgs.gov/regional/nca/1906/shockwaves/

Fuente: youtube.com

QuakeCaster Trailer (por volkansevilgen)

QuakeCaster is an interactive, hands-on teaching model that simulates earthquakes and their interactions along a plate-boundary fault. QuakeCaster contains the minimum number of physical processes needed to demonstrate most observable earthquake features. This tool, which is designed so that students or audience members can operate it and record its output, enables people to test and explore hypotheses for earthquake occurrence.

Fuente: youtube.com

Five myths about earthquakes

by renowned seismologist Susan Hough:

  1. Animals sense impending earthquakes: “Every pet owner understands that, say, cats and dogs sometimes behave strangely for no apparent reason; that’s what cats and dogs do. And if an earthquake had not subsequently struck, you can bet we would not be talking about strange animal behavior this week — because we wouldn’t have noticed anything out of the ordinary.”
  2. The frequency of large-scale earthquakes has spiked: “The number of earthquakes greater than magnitude 7.0 has been somewhat high in recent years but well within the range throughout the 20th century.”
  3. Small earthquakes are helpful because they release pressure and prevent larger ones: “For each unit increase in magnitude (i.e., going from 5.5 to 6.5), the energy released rises by a factor of about 30. (…) If enough stress has built up on a fault to generate a magnitude-7.0 earthquake, say, it would thus take about 1000 earthquakes with a magnitude of 5.0 to release the equivalent energy. The Earth doesn’t work that way. (…) If there is significant strain energy to be released, it must be released in large earthquakes.”
  4. “Don’t worry, it was just an aftershock.”: “The implication is that an aftershock is somehow a less worrisome event. Yet, as far as we understand, an aftershock of a certain magnitude is no different from an independent temblor of a similar magnitude. The shaking and rupture are the same; the energy released is the same. And aftershocks can be more damaging than larger “mainshocks” if they strike closer to population centers.”
  5. Earthquakes are a West Coast problem: “As millions of people on the East Coast were just reminded, less active does not mean inactive. By the end of the 19th century, two of the most notable temblors in the United States were the 1886 quake in Charleston, S.C., and a sequence of large events centered near the boot-heel along the New Madrid Fault of Missouri in 1811-1812. We don’t know exactly when or where the next Big One will hit the United States, but the central and eastern United States will inevitably experience large quakes in the future. (…) You have been warned.”
After an earthquake, heavier sand set loose in landslides settles first, while water is still sloshing around, forming recognizable patterns; thicker layers of mud settle on top in calmer waters over a longer time. This core was taken from the sea floor in the Canal de Sud, off the coast of Hispaniola. Source: McHugh et al., 2011. (via LDEO)
Pop-upView Separately

After an earthquake, heavier sand set loose in landslides settles first, while water is still sloshing around, forming recognizable patterns; thicker layers of mud settle on top in calmer waters over a longer time. This core was taken from the sea floor in the Canal de Sud, off the coast of Hispaniola. Source: McHugh et al., 2011. (via LDEO)

Fuente: ldeo.columbia.edu

This is very cool: seismometers deployed across the United States detected the seismic waves from the magnitude 5.9 earthquake that hit Virginia on August 23, 2011. In this animation showing the data you can actually see the wave rippling across the country! (via Bad Astronomy)

Fuente: blogs.discovermagazine.com

The earthquake’s epicenter was about 60 km (~40 miles) northwest of Richmond, Virginia and occurred in the central Virginia seismic zone- an area of modest (or so we thought), but persistent seismic activity in the Piedmont. This region is laced with ancient faults that formed 200 to 300 million years ago when Virginia was at the frontline in an ugly collision between tectonic plates. I study these fault zones. Today’s temblor makes it clear that these faults are 1) not inactive and 2) have the potential to produce significant and damaging earthquakes. We have much to learn about the stresses that cause faults to slip this far from modern tectonic plate boundaries (in this case at the Mid-Atlantic Ridge some 3,000 km from central Virginia) and the hazards that these old, but restless, faults pose. It’s why we do research at William & Mary. (via Chuck Bailey)
Pop-upView Separately

The earthquake’s epicenter was about 60 km (~40 miles) northwest of Richmond, Virginia and occurred in the central Virginia seismic zone- an area of modest (or so we thought), but persistent seismic activity in the Piedmont. This region is laced with ancient faults that formed 200 to 300 million years ago when Virginia was at the frontline in an ugly collision between tectonic plates. I study these fault zones. Today’s temblor makes it clear that these faults are 1) not inactive and 2) have the potential to produce significant and damaging earthquakes. We have much to learn about the stresses that cause faults to slip this far from modern tectonic plate boundaries (in this case at the Mid-Atlantic Ridge some 3,000 km from central Virginia) and the hazards that these old, but restless, faults pose. It’s why we do research at William & Mary. (via Chuck Bailey)

Fuente: blogs.wm.edu

Earthquake location and magnitude (by GNSscience)

John Ristau shows how seismic waves are analysed to find the source location and magnitude of an earthquake.

Fuente: youtube.com

A 3-D view of the surface rupture of the April 4, 2010, El Mayor–Cucapah Earthquake (red line) reveals a new fault line connecting the Gulf of California with the Elsinore fault, which is likely to become the main fault at the boundary between the Pacific and the North America plates. Credit: Caltech’s Tectonics Observatory. (via Caltech)
Pop-upView Separately

A 3-D view of the surface rupture of the April 4, 2010, El Mayor–Cucapah Earthquake (red line) reveals a new fault line connecting the Gulf of California with the Elsinore fault, which is likely to become the main fault at the boundary between the Pacific and the North America plates. Credit: Caltech’s Tectonics Observatory. (via Caltech)

Fuente: mr.caltech.edu

Top