Earth's Inner Inner Core

Reading seismic waves that resonate in the aftermath of an earthquake, seismologists have discovered the dense, inner core at the center of the Earth has itself a distinct inner core of about half the diameter, both cores composed of iron crystals but with different and unique properties, possibly different crystalline phases.

Earthquake Lights Explained

New research finds that mysterious lights reported for centuries before or during seismic activity are associated with areas of geological rift zones, and are theorized to be electrical charges generated from stresses between rocks that travel vertically along fault lines.

Seismic Waves Reveal Hotspots

Scientists have taken advantage of a previously unknown type of slow-moving seismic waves to map channels of heat flow and "hotspots" of volcanic surfacing in Earth's mantle using new models similar to computerized tomography (CT) scans of the human body.

Meteor Shockwave Circled Globe

The shockwave from a 17-m, 10,000-ton meteor that burned up over Chelyabinsk, Russia, in February was powerful enough to circle the Earth twice, as measured by an International Monitoring System designed to detect ultra-low frequency acoustic waves (infrasound) from nuclear tests.

Moon Being Pulled Apart

NASA's Lunar Reconnaissance Orbiter (LRO) has found small valleys called graben on the Moon's surface caused by the crust stretching and breaking along these faults, with this activity considered still active as it is estimated to have occurred less than 50 million years ago.

Interior of the Moon

A new study using data from Apollo-era seismic equipment and rock samples returned from those missions has determined the deepest parts of the lunar mantle to be up to 30% molten yet the absence of active volcanoes on the surface is prevented as this lunar magma is too dense to rise to the surface.

Japan Quake Shifted Satellites

The Tōhoku earthquake that struck Japan last March was so strong as to alter Earth's gravitational field enough to change the orbit of the twin Gravity Recovery and Climate Experiment (GRACE) satellites, sensitive NASA instruments designed to map Earth's gravity field from 500 km above the surface.

Earthquake Shifts Japan

The March 11th earthquake near eastern Japan was so powerful that it moved the entire island nation down and out into the sea, with some towns such as Ishinomaki shifting 17 feet southeast and sinking by 4 feet, creating new tide schedules and flooding for many coastal towns.

Earthquake from Space

The February 22nd earthquake in Christchurch, New Zealand, has been mapped by a Japanese spacecraft in orbit, building a synthetic aperture radar interferogram showing the deformation of Earth's crust due to the magnitude 6.3 event.

Swarm of Saudi Earthquakes

With more than 30,000 earthquakes recorded between April and June 2009 in the northwest corner of Saudi Arabia, an ancient lava field known as Harrat Lunayyir, this area is shown to be unexpectedly volcanically active.

Earth's Inner Core Shifting

New theories suggest that Earth's solid inner core is slowly shifting eastward relative to its surrounding liquid outer core, which may explain discrepancies in seismic properties and a reevaluation of how the planet's magnetic field is generated and the age of the inner core.

Laptops as Earthquake Detectors

Researchers at UC Riverside and Stanford University have developed a novel method of distributed computing called the Quake-Catcher Network, which takes advantage of accelerometers built into commercial laptops and shareware to act as a low-cost earthquake warning system.

Aftershocks from Last Century

The small, sporadic earthquakes experienced recently in the American Midwest states are actually long-felt aftershocks from the devastating New Madrid earthquakes of 1811 and 1812

Elephants in Estrus Emit Low-Frequency Seismic Calls

Researchers at the Stanford University School of Medicine have discovered that female elephants in estrus can issue a low-frequency seismic call that travels through the soil.

In addition to their audible sounds, female elephants also produce low-frequency calls that can travel up to several kilometers through surface soils. Elephants have two systems that are highly developed for detecting such sounds: bone conduction, in which the low-frequency signals are detected by the bones in the feet and travel internally to the middle ear; and somatosensory reception, in which specialized nerve cells in the feet send signals directly to the brain.

Bull elephants can detect these low-frequency signals by using their feet and placing their trunks to the ground. Experiments showed that elephants placed their bodies perpendicular to the direction of the sound, creating the maximum distance between detection points to distinguish the source. Placing the trunk to the ground allows another detection point, allowing the elephant to triangulate the origin of the sound.

Seismic communication has been found to be used in some insect species but this is the first evidence for its application in mammals. Humans also possess both methods of sound detection, although our ability to use vibrations for communication is much less developed.

These results were originally announced in 2007 by the Stanford University School of Medicine.

Source: ScienceDaily

Major New Fault Discovered in Eastern Arkansas

Scientists at the Arkansas Earthquake Center at the University of Arkansas at Little Rock have discovered a major, previously unknown fault in Arkansas that could trigger up to a magnitude 7.0 earthquake.

The new fault is near the town of Marianna in eastern Arkansas, about 100 miles east of Little Rock. It was indicated by stretches of fine sand with fertile soil, the result of liquefied sand bubbling up through underground vents. Ground radar and samples confirmed the existence of the fault, which likely formed within the past 5000 years. This fault is separate from the New Madrid Seismic Zone, an area stretching south into Arkansas from New Madrid, Missouri. This zone is a major fault line and was responsible for the widely destructive New Madrid earthquakes of 1811 and 1812, estimated to be around magnitude 8.0.

Researchers have expressed concerns over natural gas pipelines and other industrial conduits crossing this fault. This infrastructure is not required to have the more robust safety features as similar equipment in earthquake-prone southern California.

These results were presented on January 21st at a luncheon at the University of Arkansas Clinton School of Public Service.

Source: Yahoo!; Photo: Wikipedia