Solar Eruptions Cause Sunquakes

A study led by UCL's Mullard Space Science Laboratory has shown for the first time that sunquakes can be produced during eruptions of magnetic field and charged particles, as the immense magnetic structure blasts off into the Solar System. 

The results were presented by Dr Sergei Zharkov at the National Astronomy Meeting 2012 in Manchester on Friday 30th March 2012.

The first observation of a sunquake was reported by Kosovichev and Zharkova in the late 1990s. During the last decade it has become well established that explosions in the Sun's atmosphere, known as solar flares, can create sunquakes through the impact of powerful beams of particles which travel into the Sun.

This new study shows that eruptions of material known as coronal mass ejections are also able to produce sunquakes.

The authors studied an eruption that took place on 15 February 2011 and found that sunquakes 1000 times more powerful than the Great East Japan Earthquake (and subsequent tsunami), March 2011, were triggered at the two ends of the erupting rope of magnetic field.

This indicates that the sudden expansion of the magnetic field that takes place as the eruption occurs is likely to play an important role in generating the quakes.

The eruption raced through the Solar System with an average speed of 600 km/s and was Earth directed, driving a geomagnetic storm and a beautiful display of the aurora when it reached us.

"Sunquakes were first predicted in 1972 by Wolff and are seen at the Sun's surface as circular ripples emanating outward, looking much like those produced as a stone is dropped into to a pond. (Wolff referred to them as like 'trapped sound waves')

"However, they are actually caused by sudden a release of energy below the solar surface that produces sound waves which bend and travel up to the surface of the Sun, lifting it and producing the ripples," said Zharkov.

These spectacular events are helping scientists understand how energy and momentum are transported from the Sun's atmosphere down to the surface and into the interior.

With solar activity currently increasing, and due to peak in 2013, more sunquakes will be observed helping unravel the mechanisms that cause them.

HiRise Images: Mars rocks indicate relatively recent quakes, volcanism

Images of a martian landscape offer evidence that the Red Planet’s surface not only can shake like the surface of Earth, but has done so relatively recently.

If Marsquakes do indeed take place, said the scientists who analyzed the high-resolution images, our nearest planetary neighbor may still have active volcanism, which could help create conditions for liquid water.

With High Resolution Imaging Science Experiment (HiRISE) imagery, the research team  examined boulders along a fault system known as Cerberus Fossae, which cuts across a very young (few million years old) lava surface on Mars.

By analyzing boulders that toppled from a martian cliff, some of which left trails in the coarse-grained soils, and comparing the patterns of dislodged rocks to such patterns caused by quakes on Earth, the scientists determined the rocks fell because of seismic activity.

The martian patterns were not consistent with how boulders would scatter if they were deposited as ice melted, another means by which rocks are dispersed on Mars.

Gerald Roberts, an earthquake geologist with Birkbeck, an institution of the University of London, who led the study, said that the images of Mars included boulders that ranged from two to 20 meters (6.5 to 65 feet) in diameter, which had fallen in avalanches from cliffs.

The size and number of boulders decreased over a radius of 100 kilometers (62 miles) centered at a point along the Cerberus Fossae faults.


“This is consistent with the hypothesis that boulders had been mobilized by ground-shaking, and that the severity of the ground-shaking decreased away from the epicenters of marsquakes,” Roberts said.

The study, by Roberts and his colleagues, will be published Thursday in the Journal of Geophysical Research-Planets, a publication of the American Geophysical Union (AGU).

Chile quake produces tsunami alert in Pacific

BBC News - Map: Chile quake tsunami

The Chile earthquake caused a tsunami which surged across the Pacific, as the map below shows.