Joe Namath
LARGEST QUAKES -
This morning -
None 5.0 or higher.
Yesterday -
2/26/11 -
5.2 CENTRAL EAST PACIFIC RISE
5.2 EASTERN HONSHU, JAPAN
5.2 NEAR EAST COAST OF HONSHU, JAPAN
5.1 OFF EAST COAST OF HONSHU, JAPAN
5.9 SANTA CRUZ ISLANDS REGION
5.2 LOYALTY ISLANDS
2/25/11 -
5.0 KEP. MENTAWAI REGION, INDONESIA
5.7 VERACRUZ, MEXICO
NEW ZEALAND - That wasn't an aftershock," a geologist says of the earthquake that struck Christchurch with deadly force last week. He has questions about whether last week's tremor was an aftershock of last September quake or a new quake in its own right. "It might be a separate earthquake, part of a sequence of earthquakes. It is quite far from the Darfield aftershock cloud, and its fault plane solution is different. However, there are a number of examples of earthquake sequences migrating along a fault plane. One rupture builds up strain on other parts of the fault, and causes other parts to rupture. Analogous to pulling buttons off a shirt."
It generally takes many years before seismic activity can be considered a new quake rather than an aftershock of a previous one. "That's a point of debate among seismologists. But you can't paint all aftershock series with the same brush." More detailed investigations will have to wait until the search and recovery operation was completed.
Although in the South Island the Hope, Marlborough and Alpine faults are better known, earthquakes near or under Christchurch were not unexpected. The NZ Earthquake Commission in 1991 predicted moderate earthquakes under the Canterbury Plains and Christchurch itself. It also signalled liquefaction. With the benefit of hindsight, perhaps a seismic survey of the Christchurch metropolitan area might have given some warning. Tuesday's quake caused so much damage because the shaking was very intense. Peak ground acceleration was up to 2.2 times gravity. "Most cities in the world would be totally flattened by such acceleration." "You have to realise that New Zealand has some of the strongest building codes in the world, and those building codes are respected. That means you have loss of life, but it's in the dozens or maybe 100 or 200. If the same earthquake were to happen under a city of that size in a developing country, the number of deaths would be in the thousands, if not tens of thousands. Turkey, for example, had great building codes but that didn't keep tens of thousands of people from getting killed in the 1999 Izmit 7.6-magnitude earthquake. Because they weren't paying attention to those codes."
Did demolition work affect the Canterbury Television building? - The scene of the biggest loss of life in last Tuesday's earthquake is likely to be examined by an inquiry into the disaster as a possible factor in the building's collapse. Questions have been raised as to whether the building was weakened by the demolition work the day before the earthquake struck. Contractors clearing a site next door to the building drilled holes in the back wall of CTV, next to the Cathedral Square side, along the ground floor and also the second storey of the building. The holes were meant for wooden batons attached to the outside wall to support the neighbouring demolition. "I went down to have a look and said to one of the construction guys, 'This doesn't look too smart, the wall looks pretty flimsy to me'. "And he said, 'Nah, nah - we know what we're doing'.
Fifteen CTV staff are believed to be among an estimated 122 people missing in the building rubble in Madras Street. A formal inquiry will be held into why two of the city's major office buildings collapsed; why the 1960s CTV building and the more modern Pyne Gould Guinness building pancaked during the quake.
The number of confirmed fatalities from Tuesday's 6.3-magnitude quake reached 147 late yesterday, but police fear more than 50 people still listed as unaccounted for lie dead in the rubble of New Zealand's second-largest city, with a population of about 390,000. The initial evidence from Tuesday's quake was that buildings constructed after 1992 had withstood it. The CTV building was built in 1960, just before the updating of the 1931 earthquake code, which followed the Napier quake. The PGG building was built in the mid-80s, and under current laws is not required to be compliant with the 1992 standard. Talk has begun among civic leaders and building experts on whether Christchurch needed to be dramatically remodelled to protect it from a repeat of last week's disaster. "One of the things we are going to need to look at is the psychology of the people who have been in these buildings. There is a lot of people who basically won't work in high-rise buildings again. (photo)
VOLCANOES -
PHILIPPINES - Bulusan - Heavy rains push Bulusan lahar, huge rocks into Irosin river. Despite a relatively calm Mt. Bulusan, lahar started to flow down its slopes into a river in Irosin town on Sunday, hours after the rain that began Saturday night. Close to 100,000 residents in slopes around the volcano, particularly in Irosin and Juban, feared flash floods in case torrential rains followed. But on Sunday that the lahar flows were still confined to the Rangas River channel. Lahar and other volcanic sediments started flowing from the slopes of Mt. Bulusan at 10 a.m. on Sunday, causing widespread fear of lahar overflowing to residential areas close to the river system. “We were alarmed because what we see were mostly lahar, sand and big rocks cascading down the slopes of the volcano at a velocity of about 70 kilometers per hour. There were minimal water component compared to the previous lahar flows in November and December,."
Government volcanologists earlier warned of lahar flows in the event of a downpour as tons of ashes and other volcanic debris were deposited along the slopes of the Cogon gully. Mt. Bulusan dumped some 700,000 cubic meters of debris in an ash explosion on Feb. 21, adding to the stockpile from previous explosions since Nov. 6. 2010. The rain stopped at noon Sunday but the lahar flow continued. The Telemetered Seismic Network recorded five volcanic earthquakes during the past 24 hours. Steam activity was not observed due to clouds obscuring the vents and summit crater. Mt. Bulusan remained at alert level No. 1. This means that the source of activity is hydrothermal and shallow.
Taal - At least seven volcanic quakes were recorded around restive Taal Volcano in Batangas in the last 24 hours, state volcanologists said Friday.
Yale scientists predict volcanic explosions using sound waves - The team created a model that judges the volatility of a volcano, using by the frequency of the sound that it emits. The average volcano emits frequencies between 0.5 and 2 Hz. Minutes before an explosion that frequency jumps to a wider range between 0.5 and 7 Hz. The sound is caused by the magma and gas within the volcano interaction, according to the model. Scientists claim that this could help warn people before a violent explosion, but the model’s usefulness has been fiercely debated. “Is a minute’s warning enough for people living near an explosive volcano?”
TROPICAL STORMS -
No current tropical cyclones.
WESTERN AUSTRALIA - Tropical low spells possible cyclone. The Kimberley and Pilbara are again told to prepare for a possible cyclone, with a tropical low developing. This comes after persistent cyclone Carlos lashed the North of the region.
PHILIPPINES - State weather forecasters are monitoring a low-pressure area that might become the first cyclone to enter Philippine territory this year. The LPA may enter Philippine territory this weekend. "The LPA is not yet active but it is already a full one. It is still outside the Philippine area of responsibility as of Friday but it is closely following a shallow low-pressure area (SLPA) already in Philippine territory." Should the LPA eventually become a cyclone in Philippine territory, it will be codenamed "Amang." The LPA is tailing is at 900 km east of Davao City.
