Archives
Geologists Witness Possible Birth of an Ocean Basin
Posted on Monday, December 12, 2005 @ 10:54 am by Dave Schumaker
A rapidly growing fissure in the Afar Desert of Africa (part of the Great Rift Valley) could signal the beginnings of a new ocean basin according to researchers from Addis Ababa University.
“We believe we have seen the birth of a new ocean basin,” said Dereje of Addis Ababa University. “This is unprecedented in scientific history because we usually see the split after it has happened. But here we are watching the phenomenon.”
[...]
“It’s amazing,” the BBC quoted one of the Afar researchers, Cindy Ebinger of the Royal Holloway University of London, as saying in San Francisco. “It’s the first large event we’ve seen like this in a rift zone since the advent of some of the space-based techniques we’re now using, and which give us a resolution and a detail to see what’s really going on and how the earth processes work.”
This page from the Global Volcanism Program has more information, as well as pictures.
Most Detailed Map of San Andreas Fault
Posted on Wednesday, December 7, 2005 @ 3:04 pm by Dave Schumaker
More news from this years 2005 AGU meeting. Scientists from Ohio State University released the first images of the most detailed survey ever conducted along the San Andreas Fault. Using GPS technology, as well as LIDAR systems mounted in a small aircraft, they flew along 1,000 kilometers of the fault. Their data has 5cm vertical resolution. The hope is to compare this high resolution data of before an earthquake occurs to high resolution data taken after a large earthquake occurs to further characterize what happens during an earthquake.
They loaded their equipment on board a twin-engine Cessna airplane, and covered nearly 1,000 kilometers (621.37 miles) of the fault in two months of flights, during May and August of 2005.
Bevis recalled that the flights required near-heroic effort from the team pilots. “We had to fly low and closely manage the orientation of the aircraft at all times so we knew exactly where the laser on the lidar instrument was pointing,” he said.
SAFOD Insights into the “Earthquake Machine”
Posted on Tuesday, December 6, 2005 @ 3:21 pm by Dave Schumaker
Scientists working with the San Andreas Fault Observatory at Depth will be presenting two talks at AGU this week, detailing new insights to how earthquakes start. Earlier this summer, the SAFOD borehole completed a major goal of drilling through the active fault zone along the San Andreas Fault near Parkfield.
One of the interesting discoveries along the fault involves nonvolcanic tremors that seem to correlate well with actual earthquakes that happen at later point in time.
From 2000 to 2003, before SAFOD drilling began, researchers from the University of California-Berkeley recorded 110 nonvolcanic tremor events along the San Andreas Fault near Parkfield. Their data showed a remarkable correlation between the frequency of tremor events and the subsequent earthquakes. The scientists discovered that an increase or decrease in the number of tremor events over a certain period of time would usually be matched by a similar increase or decrease in the number of microearthquakes (magnitude 2.1 or smaller) several weeks later, suggesting a possible causal relationship.
40 Acres of Hawaii Falls into Ocean
Posted on Monday, December 5, 2005 @ 11:32 pm by Dave Schumaker
Last week, roughly 40 acres of coastline at Hawaii Volcanoes National Park broke apart and fell into the ocean. The U.S.G.S. has some beautiful pictures of lava pouring out of the newly exposed cliff face from lava tubes.
The collapse of solidified lava shelf and sea cliff Monday was the largest since Kilauea Volcano began its current eruption in 1983.
Jim Kauahikaua, scientist-in-charge of the U.S. Geological Survey’s Hawaiian Volcano Observatory, said a collapse warning was issued in June because the shelf had become large and had formed cracks. Large collapses had happened in the area before.
Here is a live view of the Pu`u `O`o crater in Hawaii via a webcam (note that it’s currently evening there as I posted this).
World’s Tallest Building Responsible for Increased Seismicity?
Posted on Sunday, December 4, 2005 @ 11:47 pm by Dave Schumaker
A reader by the name of Lonney submitted the following news item. A geologist working for the Institute of Earth Sciences at the Academia Sinicathe has hypothesized that Taipei 101, currently the world’s tallest building, may be responsible for increased seismicity in the city of Taipei. Since its completion in 1997, there has been an increase in the amount of microearthquakes that have occurred in Taipei.
But the city has experienced more micro-earthquakes (of magnitude 2.0-2.5 on the Richter scale) since construction began on the 508 meter (1,667 foot) skyscraper in 1997, he said.
Two earthquakes of magnitude 3.8 and 3.2 occurred directly beneath Taipei 101 in October 2004 and March 2005, he said.
“There is a distinct possibility of earthquakes being triggered by the recent construction of the world’s highest building, the imposing Taipei 101,” Lin wrote in an article published in the Geophysical Research Letters Vol. 32 on Nov. 30.
Induced seismicity is not unheard of, though it is usually associated with the construction of reservoirs. Also, here is an abstract from Harvard on induced seismicity at The Geysers, California, where geothermal power is produced.