Major Earthquake Hits Western China

21 03 2008

BEIJING (AP): A major earthquake struck western China early Friday, but there were no reports of casualties.

The 7.2 magnitude quake hit at 6:33 a.m. (2233 GMT Thursday), about 140 miles southeast of the city of Hotan in southwest Xinjiang province, the U.S. Geological Survey reported.

A spokesman for China’s Earthquake Administration confirmed the earthquake, but said it had a 7.3 magnitude.

There were no reports of anyone hurt so far, he said, and the area is sparsely populated.

There were four aftershocks in the region, ranging from 5.0 to 5.2 magnitude, according to a notice on the Earthquake Administration’s Web site.

Xinjiang is a predominantly Muslim region with a culture that is distinctly different from that of China’s ethnic Han majority.

Dale Grant, a USGS geophysicist, described the area as “very seismically active,” and said Friday’s temblor was the biggest there on record.

The Earthquake Administration said the last earthquake in the Hotan region took place in 1992 and had a 5.9 magnitude.





Eruption at Kilauea Volcano, First since 1924

21 03 2008

USGS HVO News Release
March 19, 2008

At 2:58 a.m. H.s.t on Wednesday, March 19, 2008, a small explosion occurred at Halema‘uma‘u Crater at the summit of Kilauea Volcano in Hawai‘i Volcanoes National Park. This event was erroneously reported as an earthquake earlier this morning. The explosion scattered debris over an area of about 75 acres (30 hectares), covering a portion of Crater Rim Drive and damaging the Halema‘uma‘u overlook. No lava was erupted as part of the explosion, suggesting that the activity was driven by hydrothermal or gas sources.

In addition to damaging the overlook, explosive debris covers the trail to the overlook, the Halema‘uma‘u parking area, and the portion of Crater Rim Drive adjacent to the parking area. On Crater Rim Drive the debris was up to 2 centimeters in size, with the size and thickness of debris increasing toward the overlook. The largest observed block ejected during the explosion was about 1 cubic meter (35 cubic feet) and must have been propelled from the vent located more than 70 m (230 feet) below the crater rim. Small impact craters from 30 cm (1 foot) blocks are abundant in the Halema‘uma‘u overlook area. Rock debris also extends halfway across the floor of Halema‘uma‘u Crater. The debris is composed of rock fragments that were derived from the walls of Halema‘uma‘u Crater. No fresh lava was observed on the floor of Halema‘uma‘u or in the ejected debris.

At 2:55 am, the Hawaiian Volcano Observatory recorded a series of seismic events that may have been shallow, high-frequency earthquakes or minor explosions. The main explosion at 2:58 was associated with long period seismicity. Low frequency sound waves were also detected by the University of Hawai`i infrasound laboratory, operated by Dr. Milton Garces. These signals have persisted through this morning indicating continuing energetic release of gas from the vent in Halema‘uma‘u Crater.

The explosion produced a small crater along the east wall of Halema‘uma‘u that is about 20-30 meters (65-100 feet) in diameter. The crater occupies the area in which incandescence had been observed during the previous week. Sulfur dioxide emissions from the new explosion crater are still elevated, and sounds of rock breaking are frequent.

This is the first explosion in Halema`uma`u crater since 1924 and the first eruption of any kind in Kilauea caldera since September 1982.

Future explosive activity is possible and the Hawaiian Volcano Observatory continues to monitor the activity. Photos, text updates, a new Halema`uma`u crater webcam, and details about the Kilauea 1924 explosive eruption can be found at the HVO website http://hvo.wr.usgs.gov.

Images are at here.

Video from Channel 9 KGMB





The Core of the Matter is the Matter in the Core

18 03 2008

Using both newly acquired data and legacy data, geologists have confirmed the discovery of the Earth’s innermost core, and have created a three-dimensional model that describes the seismic anisotropy and texturing of iron crystals within the inner core.

Composed mainly of iron, Earth’s core consists of a solid inner core about 2,400 kilometers in diameter and a fluid outer core about 7,000 kilometers in diameter. The inner core plays an important role in the geodynamo that generates Earth’s magnetic field.

The solid inner core is elastically anisotropic; that is, seismic waves have different speeds along different directions.

The project took place at the University of Illinois.

Read the whole article here.