teaching them to walk and talk
and the next twelve
telling them to sit down and shut up.**
Phyllis Diller
LARGEST QUAKES -
This morning -
None 5.0 or higher.
Yesterday -
2/24/11 -
5.4 FIJI REGION
5.0 OFFSHORE BIO-BIO, CHILE
5.5 TONGA
NEW ZEALAND - The death toll from Tuesday's deadly magnitude 6.3 earthquake in New Zealand climbed to 98, with 226 people listed as missing. The "loss of life could be more substantial than any one of us had ever dreamed of."
NEW ZEALAND - Christchurch earthquake: Deadly tremors rebounded on city. The hard rock near the quake's epicentre close to Lyttelton may have compounded the effect of the tremor by reflecting greater seismic activity towards the city. Seismologists say the unlikely combination of depth, size and proximity to a populated region all contributed to the devastation. The location of the epicentre close to the Port Hills, which are largely basalt rock, may have also played a role in the catastrophic damage. Seismic activity travels in waves, so it could be compressed, refracted or reflected like an optical waveform. While the waves could be dispersed or absorbed by some properties, they could also rebound off hard surfaces.
"We suspect that the epicentre was probably on the north side of the Port Hills, where a huge amount of energy would have been literally 'pinged' off the basalt rock, almost behaving like a mirror. You can imagine an explosion going off and energy going out towards Christchurch city, but a lot of energy also hitting the hard rock at depth, then being reflected, bounced back and compounding the effect." This event, called seismic lensing, could explain the hotch-potch damage to the city and suburbs. "It'll partly be why there are some parts of Christchurch bizarrely much worse affected than others. A lot depends on that nature of the ground immediately beneath the building, but you have to remember that these waves can behave in strange ways. It could be that the Pyne Gould building, for instance, might have conformed to all the building standards but was hit by an absolute ROGUE WAVE." A previous Californian earthquake, which struck inland, mysteriously brought down several buildings in Santa Monica, a huge distance from the original faultline.
Seismologists are still digging through a wealth of seismic data to understand how a magnitude 6.3 quake produced the largest recorded ground-shaking in New Zealand. The quake - which is an aftershock of the September tremor - reached 9 on the Modified Mercalli intensity scale, which runs to 12. This intensity destroys most buildings of a low standard, and even hurts post-1980s buildings which are specially designed to withstand earthquakes. "What the instruments are telling us is that it was a very energetic earthquake for its size." The previously unknown faultline ran east-to-west from Taylors Mistake to Halswell. It was roughly 3km to 12km deep and 17km long. The aftershocks that were occurring along this faultline were tailing off more quickly than the September quake, but would still continue for months. There have been more than 120 shocks since Tuesday's tremor, the greatest of which was magnitude 5.7.
A team of scientists failed to find a surface rupture in the hills above the epicentre, which meant it was more difficult to understand the nature of the fault and the size of the "stress drop" - the difference between the stress across a fault before and after an earthquake. One, predicted that the fault had been "well-cemented" after lying quiet for thousands of years. "So when it went, it went with a particularly violent bang." While the energy of September's Darfield quake was the equivalent of a car slamming on its brakes sharply, Tuesday's Lyttelton quake appeared to be a longer, heavier release of tension. Satellite images should soon determine how much the earth moved, and the size of the stress drop.
VOLCANOES -
INDONESIA - The mud volcano that has displaced more than 13000 Indonesian families WILL ERUPT FOR AT LEAST A QUARTER OF A CENTURY, emitting belches of flammable gas through a deepening lake of sludge, scientists reported on Thursday.
PHILIPPINES - Government volcanologists yesterday allayed fears of Sorsogon residents of a major eruption of Bulusan volcano, saying that what was ejected last Monday were merely old deposits and not “fresh ones” as earlier reported.
TROPICAL STORMS -
Cyclone CARLOS was 577 nmi NW of Perth, Australia.
