Transcript 投影片 1 - Academia Sinica

Earthquake Information
Summary:
Magnitude Mw 7.9
Region
SOLOMON ISLANDS
Date time
2007-04-01 at 20:39:55.2 UTC
Location
8.33 S ; 156.92 E
Depth
10 km
Distances
1078 km E Port moresby (pop 283,733 ; local time 06:39 2007-04-02)
278 km SE Arawa (pop 40,266 ; local time 06:39 2007-04-02)
27 km S Gizo (pop 6,154 ; local time 07:39 2007-04-02)
credit EMSC
Page created by W. G. Huang
2007-04-01 at 20:39:55.2 UTC
Mw=7.9
Page created by W. G. Huang
Quick Moment Tensors solutions
2007-04-01 at 20:39:55.2 UTC
Mw=7.9
Page created by W. G. Huang
Tectonic summary
Location of the earthquakes relative to Australia.
Credit USGS
Regional schematic plate boundary map
Page created by W. G. Huang
Regional topographic map showing the Solomon Islands, and
the surrounding trenches
The Solomon Islands are located between
156° and 170° E longitude and 5° and 12° S
latitude, and form a long (1200 km), thin
(250 km) archipelago oriented NW - SE.
They are positioned in the collisional zone
between the Australian and Pacific plates,
and consist of a complex series of crustal
units. Deep ocean lies to the north-east and
south-west. The islands are geologically
bound by two trenches: the Vitiaz trench in
the north-east, and the New Britain-San
Cristobal trench in the south-west.
The Vitiaz trench is over 3000 km long, with depths up to 6000 m (6 km). The New Britain-San
Cristobal trench reaches depths of up to 9000 m (9 km). Subduction (or sinking) of the Australian
plate beneath the Solomon Island occurs along the New Britain-San Cristobal trench.
Credit National Geographic
Page created by W. G. Huang
Solomon Islands Map
the earthquake struck near Gizo
credit NEWS.com.au
The Solomon Islands is a nation in Melanesia,
east of Papua New Guinea, consisting of nearly
one thousand islands. Together they cover a land
mass of 28,400 square kilometres (10,965 sq mi).
The capital is Honiara, located on the island of
Guadalcanal.
The Solomon Islands are believed to have been
inhabited by Melanesian people for thousands of
years. The United Kingdom established a
protectorate over the Solomon Islands in the
1890s. Some of the most bitter fighting of World
War II occurred in the Solomon Islands campaign
of 1942-45, including the Battle of Guadalcanal.
Self-government was achieved in 1976 and
independence two years later. The country
remains a Commonwealth Realm.
Since 1997 ethnic violence, government
misconduct and crime have undermined stability
and civil society. In June 2003 an Australian-led
multinational force, the Regional Assistance
Mission to the Solomon Islands (RAMSI), arrived
to restore peace and disarm ethnic militias.
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Areas affected by the main and aftershock earthquakes
Credit USGS
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Houses float in sea of devastation
A transport boat is grounded in Gizo, in the
Solomons.
the first aerial footage shows the destruction in
Gizo left by yesteray's tsunami
credit NEWS.com.au
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Tsunami Event - April 1, 2007 Solomon Islands
credit ReliefWeb
Earthquake and tsunami wipe out whole
communities in Solomons
· 8.0 magnitude shock kills 12, with many missing
· 10m wave washes away whole villages
Walter Nalangu in Honiara, and Reuters
Tuesday April 3, 2007
A powerful earthquake and tsunami struck the tiny Solomon Islands yesterday,
swallowing entire villages and killing 12 people, with many more reported missing.
The quake, with a magnitude of at least 8.0, leveled buildings and damaged a hospital
on the island of Gizo, northwest of the Solomons capital, Honiara. A tsunami
described by a witness as being the height of a two-storey building sucked homes into
the sea as thousands of panicked residents fled for higher ground.
At least seven people died in Gizo, many trapped in their homes when waves swept
through the town. Other bodies could be seen but not reached because of huge waves
crashing ashore. "The wave was up to 10 metres (32ft) high in some villages,"
government spokesman Alfred Maesulia told Reuters. "Some villages have been
entirely washed away."
credit The Guardian
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Solomons' disaster management authorities said two-way radio communications
problems were preventing an assessment of damage on the island of Simbo, where
residents reported waves hitting houses 200m inland.
Geological agencies, including those in Australia and Japan, put the magnitude of
the quake at 8.1 while the US Geological Survey (USGS) revised its earlier estimate
to 8.0. The initial tremor was followed around seven minutes later by a second one,
centred further to the west, of magnitude 6.7, USGS said.
Gary Gibson, who chairs the International Seismological Centre executive
committee, said the quake was the biggest to hit the Solomons since 1900. "An
earthquake of this size would involve a rupture of more than 10,000 square
kilometres of fault area ... about 100 kilometres by 100 kilometres," he said.
Kevin McCue, director of the Australian Seismological Centre, said there was a
strong chance that there would be more earthquakes in coming days on an undersea
trench west of the Solomons. "This region typically has double earthquakes, six
sets of them since 1907," Mr McCue said, adding residents and rescue teams
should be on alert for more quakes of up to magnitude 7.5.
The Solomons lie on the so-called Pacific Ring of Fire where volcanic activity and
earthquakes are fairly common.
credit The Guardian
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Research animations of the April 1, 2007 Solomon Islands tsunami propagation created with
experimental runs of the MOST tsunami forecast model and including DART™ buoy data.
Yellow squares indicate DART™ buoy locations.
Propagation in the Pacific Ocean
(14.2 MB animation)
Maximum wave height distribution
credit NOAA / NOAA Center for Tsunami Research
The animation and graphic display
qualitative and quantitative information
about the tsunami propagation including
tsunami wave interaction with ocean floor
bathymetric features, and neighboring
coastlines. The tsunami radiation pattern is
indicated with color coded information
about the maximum wave height at different
locations throughout the Pacific Ocean.
The timer and moving yellow squares
indicate time elapsed since time of the
earthquake, providing an estimate of
tsunami arrival time at different locations
(left). Please note that part of the 1 minute
data of 52403 DART is missing and is
displayed as a straight line on the animation
plot.
Page created by W. G. Huang