RING OF FIRE QUAKES INTENSIFY
June 26 According to Indonesia's Meteorology and
Geophysics Agency, a 6.4 magnitude earthquake has hit, centered
about 53 kilometers (33 miles) northeast of Waren, a town on the
northern coast of Papua.
Last week there were a significant number of quakes of 5 or
above throughout the Ring of Fire, including a major 7.2
earthquate late Thursday, July 23, in Alaska, USA.
The other nations to record moderate to strong earthquakes
last week include Japan, Fiji, Panama, Papua, New Guinea,
Indonesia, Costa Rica, Solomon Islands, Vanuatu, Tonga, Samoa,
Chile, Peru, Bolivia, Argentina and Antarctica.
Last week four earthquakes measuring in excess of 5.0 on the
Richter Scale struck Alaska. A large earthquake (magnitude 6.7)
struck off the coast of Honshu, Japan, Wednesday night, June 22.
A series of large tremors measuring greater than 5 have been
recorded there since Wednesday night.
A 6.2 magnitude earthquake struck the Solomon Islands Friday
morning, June 24. It was the third strong earthquake to hit the
region last week.
On Thursday night Tonga was hit by a moderate earthquake.
On Wednesday night a magnitude 5.2 earthquake was recorded
in Fiji. The region was also hit by 5.5 and 5.1 magnitude quakes
on Saturday and Sunday.
The Catamarca region of Argentina was hit by a moderate
earthquake on Wednesday.
A 5.2 magnitude quake struck the South Island of New Zealand
on Tuesday.
Also on Tuesday, northern Sumatra in Indonesia was shaken by
a magnitude 5.2 tremor.
A strong earthquake struck the Antofagasta region of Chile
Monday afternoon.
A 5.4 magnitude quake hit the island nation of Vanuatu on
Monday.
On Sunday a 5.1 magnitude earthquake struck Panama.
A 4.9 magnitude quake was recorded along the
Pacific-Antarctic Ridge on Sunday afternoon.
On Saturday night the northern coast of Peru experienced a
moderate 5 magnitude earthquake and on Saturday morning a
magnitude 5.2 tremor was recorded in Papua New Guinea.
OBAMA BUDGET CUTS WILL KILL: PORTLAND CONFERENCE SAYS WEST COAST
UNPREPARED FOR INEVITABLE CASCADIA SUBDUCTION ZONE QUAKE
At the American Institute of Architects
conference held at Portland State University in Portland, Oregon,
scientists argued June 24 that within the next 50 years,
Washington state and northern Oregon face a 10 to 15 percent
probability of an offshore quake powerful enough to kill
thousands and launch a tsunami that would level coastal cities.
Off southern Oregon, the probability of an 8-or-higher magnitude
earthquake is greater -- 37 percent.
Oregon State University's Chris Goldfinger, one of the
world's top experts on subduction-zone quakes, and other
authorities, said the Northwest is dangerously unprepared for a
massive quake they consider inevitable. Oregon is not nearly as
prepared as Japan for a major earthquake, let alone a tsunami. At
least 300,000 Oregon children attend school in buildings
vulnerable to collapse when the Big One comes. Oregon stores much
of its liquid fuel, for example, in tanks on soil prone to
liquefaction along the Willamette River north of Portland.
Goldfinger and his colleagues have advanced the field of
paleoseismology, examining sediments and rocks for signs of
ancient earthquakes. They took core samples recently in Japan's
Sendai plain, confirming that the Jogan tsunami in the year 869
swept farther than the March 11 wave, stopped only by hills 3
miles inland in what is now Sendai city.
Goldfinger's team has used similar techniques to date and
fingerprint 19 undersea ruptures that have occurred during the
last 10,000 years along the entire tectonic-plate margin from
California to British Columbia.
Twenty-two more earthquakes have occurred along the southern
parts of the Cascadia zone off Oregon. Cascadia quakes also seem
to trigger activity along the San Andreas fault line to the
south.
The largest Cascadia quake, known as T11, hit 5,900 years
ago. The most recent one, called T1, occurred around 9 p.m. Jan.
26, 1700. The roughly 9-magnitude quake sent a tsunami to Japan.
That was 311 years ago. The farther south along the Northwest
coast, the more frequently quakes occur.
An 8.5-magnitude earthquake would kill an estimated 5,000
Oregon residents at minimum, said Yumei Wang, geohazards team
leader at the Oregon Department of Geology and Mineral
Industries. Many would probably die in unreinforced masonry
structures prone to collapse, she said, including school
buildings. State grants to upgrade schools and emergency
buildings have lapsed.
Many Oregon bridges are also vulnerable, said Peter Dusicka,
a PSU civil engineering professor. His modeling projects Oregon
bridge damage exceeding $1 billion from a 9-magnitude Cascadia
quake. A less powerful 6.5-magnitude earthquake in the Portland
hills would cause more than $1.5 billion in bridge damage,
Dusicka expects.
"It wasn't really until the 1990s that a worthwhile
earthquake load was considered for bridges" in Oregon, Dusicka
said. "Yet most of the building was in the '60s and '70s."
Engineers have learned, Dusicka said, that seismic
retrofitting can reduce bridge damage. Portland's Marquam Bridge,
built in 1966, had a basic retrofit in 1995 to prevent such damage.
Showing posts with label earthquake portland cascadia oregon. Show all posts
Showing posts with label earthquake portland cascadia oregon. Show all posts
Monday, June 27, 2011
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