Most natural hazard specialists believe the key to reducing losses is to use our existing knowledge of the ways earthquakes occur, and where, to implement measures that increase awareness, preparedness and resilience. The real focus needs to be on dealing with the social, political and economic barriers that prevent effective disaster risk reduction. While speculative research on prediction is an interesting exercise, and might yield unintended benefits, it is not the magic bullet that will reduce losses, no matter how appealing it might seem at first glance.
This shows the largest of the newly detected graben found in highlands of the lunar farside. The broadest graben is about 500 meters (1,640 feet) wide and topography derived from Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) stereo images indicates they are almost 20 meters (almost 66 feet) deep. Credit: NASA/Goddard/Arizona State University/Smithsonian Institution (via NASA)
Fig. 1 in P. Hammer et al., GSA Today, 21, 6 (2011): Location of transcontinental corridor (yellow lines) on a simplified tectonic age map of northern North America. Tectonic age is defined as the time since the most recent episode of tectonic deformation. Red arrows show along-strike offsets linking profile segments. The interpreted cross section incorporates Earth curvature and is displayed using a vertical exaggeration of 2:1. At this scale, features are difficult to identify; see 1:1 version extended to full lithospheric depth.
What’s it Like at the Centre of the Earth? - Horizon: The Core - BBC Two (by BBC)
http://www.bbc.co.uk/programmes/b0148vph The earth’s inner core is made of iron nickel alloy. But what happens to it under the immense temperatures and pressures found there? Professor Kei Hirose spent 10 years devising an experiment to recreate these extreme conditions. Here he reveals the results…
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.
September Nature Geoscience cover photo: Stretching of the continental crust can double its surface area, but it is unknown whether similar amounts of extension occur at depth. Seismic results from the central Basin and Range province, western USA, reveal a thick root of lithospheric mantle that has not been extended and indicates that crustal stretching is decoupled from extension at depth. The image shows badlands in Death Valley, California. See “Differential motion between upper crust and lithospheric mantle in the central Basin and Range”, by Schulte-Pelkum et al., p. 619-6326. Photo by Ian Parker.
by renowned seismologist Susan Hough:
- 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.”
- 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.”
- 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.”
- “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.”
- 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.”