Misplaced Pages

#872127

37-448: Simbo is actually two main islands, one small island called Nusa Simbo separated by a saltwater lagoon from a larger one. Collectively the islands are known to the local people as Mandegugusu, while in the rest of the Solomons the islands are referred to as Simbo. Simbo has an active volcano called Ove as well several saltwater lagoons and a freshwater lake. On April 2, 2007, Simbo was hit by

74-844: A function of the rest position x {\displaystyle {\boldsymbol {x}}} and time t {\displaystyle t} . The deformation of the medium at that point can be described by the strain tensor e {\displaystyle {\boldsymbol {e}}} , the 3×3 matrix whose elements are e i j = 1 2 ( ∂ i u j + ∂ j u i ) {\displaystyle e_{ij}={\tfrac {1}{2}}\left(\partial _{i}u_{j}+\partial _{j}u_{i}\right)} where ∂ i {\displaystyle \partial _{i}} denotes partial derivative with respect to position coordinate x i {\displaystyle x_{i}} . The strain tensor

111-471: A measles outbreak was reported and an immunisation program was underway. The island of Ranongga in the New Georgia Group was lifted three meters by the earthquake, causing its beaches to shift outwards of up to 70 meters. Large coral reefs in the area are now largely above the surface and local fishermen are worried that the fishing grounds have been destroyed. However, Australian scientists said

148-534: A tsunami triggered by the earthquake struck the Solomon Islands, wiping out thirteen or more villages. Thousands were left homeless, and damage is estimated in the millions. The largest waves were reported on the northern tip of Simbo Island, where maximum tsunami run-ups were 12 m (39 ft), completely washing away two villages, Tapurai and Riquru, and killing 10 people. In South Choiseul, waves 10 m (33 ft) high swept away villages, gardens and

185-409: A viscoelastic material, the speed of a shear wave is described by a similar relationship c ( ω ) = ω / k ( ω ) = μ ( ω ) / ρ {\displaystyle c(\omega )=\omega /k(\omega )={\sqrt {\mu (\omega )/\rho }}} , however, here, μ {\displaystyle \mu }

222-483: A P wave strikes the boundary of molten and solid cores at an oblique angle, S waves will form and propagate in the solid medium. When these S waves hit the boundary again at an oblique angle, they will in turn create P waves that propagate through the liquid medium. This property allows seismologists to determine some physical properties of the Earth's inner core. In 1830, the mathematician Siméon Denis Poisson presented to

259-483: A field hospital in Gizo, with a total of eight planned for the entire country, and also established three camps for internally displaced persons . Australian and Canadian medical teams have also been deployed across the islands. Papua New Guinea , itself affected by the tsunami, has contributed US$ 340,000 and a light plane that can better access smaller, more remote airstrips. UNICEF issued an appeal for US$ 500,000 for both

296-632: A hospital. About 900 homes were destroyed. The tsunami reached Papua New Guinea , with a family of five reportedly missing from a remote island in Milne Bay Province , which was in the tsunami's path. Beaches and ferry services in Sydney were closed due to a tsunami alert. Aid workers reported that an outbreak of diarrhoea emerged among the survivors. However, the UN reported that the outbreak and other diseases were under control as of 12 April. On 18 April,

333-425: A massive earthquake and tsunami which is now known as the 2007 Solomon Islands earthquake . A 12 m tsunami destroyed two villages, Tapurai and Riquru, on the northern side of the island. Even though the tsunami hit the villages just minutes after the earthquake nearly everyone in the villages ran for safety before the waves hit. Their astonishing response was probably due to a combination of deep ecological knowledge of

370-720: A review of long-term rehabilitation and disaster preparedness plans. The Australian government announced that a network of five tsunami warning buoys will be deployed along its Pacific coast, with two buoys stationed in the Papua New Guinea/Solomon Islands area. [REDACTED]  This article incorporates public domain material from websites or documents of the United States Geological Survey . S wave In seismology and other areas involving elastic waves, S waves , secondary waves , or shear waves (sometimes called elastic S waves ) are

407-588: A solid medium is considered isotropic if its strain (deformation) in response to stress is the same in all directions. Let u = ( u 1 , u 2 , u 3 ) {\displaystyle {\boldsymbol {u}}=(u_{1},u_{2},u_{3})} be the displacement vector of a particle of such a medium from its "resting" position x = ( x 1 , x 2 , x 3 ) {\displaystyle {\boldsymbol {x}}=(x_{1},x_{2},x_{3})} due elastic vibrations, understood to be

SECTION 10

#1732851283873

444-561: A type of elastic wave and are one of the two main types of elastic body waves , so named because they move through the body of an object, unlike surface waves . S waves are transverse waves , meaning that the direction of particle movement of an S wave is perpendicular to the direction of wave propagation, and the main restoring force comes from shear stress . Therefore, S waves cannot propagate in liquids with zero (or very low) viscosity ; however, they may propagate in liquids with high viscosity. The name secondary wave comes from

481-599: Is a complex, frequency-dependent shear modulus and c ( ω ) {\displaystyle c(\omega )} is the frequency dependent phase velocity. One common approach to describing the shear modulus in viscoelastic materials is through the Voigt Model which states: μ ( ω ) = μ 0 + i ω η {\displaystyle \mu (\omega )=\mu _{0}+i\omega \eta } , where μ 0 {\displaystyle \mu _{0}}

518-463: Is more than twice the speed β {\displaystyle \beta } of S waves. The steady state SH waves are defined by the Helmholtz equation ( ∇ 2 + k 2 ) u = 0 {\displaystyle \left(\nabla ^{2}+k^{2}\right){\boldsymbol {u}}=0} where k is the wave number. Similar to in an elastic medium, in

555-485: Is related to the 3×3 stress tensor τ {\displaystyle {\boldsymbol {\tau }}} by the equation τ i j = λ δ i j ∑ k e k k + 2 μ e i j {\displaystyle \tau _{ij}=\lambda \delta _{ij}\sum _{k}e_{kk}+2\mu e_{ij}} Here δ i j {\displaystyle \delta _{ij}}

592-1251: Is the Kronecker delta (1 if i = j {\displaystyle i=j} , 0 otherwise) and λ {\displaystyle \lambda } and μ {\displaystyle \mu } are the Lamé parameters ( μ {\displaystyle \mu } being the material's shear modulus ). It follows that τ i j = λ δ i j ∑ k ∂ k u k + μ ( ∂ i u j + ∂ j u i ) {\displaystyle \tau _{ij}=\lambda \delta _{ij}\sum _{k}\partial _{k}u_{k}+\mu \left(\partial _{i}u_{j}+\partial _{j}u_{i}\right)} From Newton's law of inertia , one also gets ρ ∂ t 2 u i = ∑ j ∂ j τ i j {\displaystyle \rho \partial _{t}^{2}u_{i}=\sum _{j}\partial _{j}\tau _{ij}} where ρ {\displaystyle \rho }

629-904: Is the density (mass per unit volume) of the medium at that point, and ∂ t {\displaystyle \partial _{t}} denotes partial derivative with respect to time. Combining the last two equations one gets the seismic wave equation in homogeneous media ρ ∂ t 2 u i = λ ∂ i ∑ k ∂ k u k + μ ∑ j ( ∂ i ∂ j u j + ∂ j ∂ j u i ) {\displaystyle \rho \partial _{t}^{2}u_{i}=\lambda \partial _{i}\sum _{k}\partial _{k}u_{k}+\mu \sum _{j}{\bigl (}\partial _{i}\partial _{j}u_{j}+\partial _{j}\partial _{j}u_{i}{\bigr )}} Using

666-506: Is the wave equation applied to the vector quantity ∇ × u {\displaystyle \nabla \times {\boldsymbol {u}}} , which is the material's shear strain. Its solutions, the S waves, are linear combinations of sinusoidal plane waves of various wavelengths and directions of propagation, but all with the same speed β = μ / ρ {\textstyle \beta ={\sqrt {\mu /\rho }}} . Assuming that

703-438: Is the stiffness of the material and η {\displaystyle \eta } is the viscosity. Magnetic resonance elastography (MRE) is a method for studying the properties of biological materials in living organisms by propagating shear waves at desired frequencies throughout the desired organic tissue. This method uses a vibrator to send the shear waves into the tissue and magnetic resonance imaging to view

740-465: The French Academy of Sciences an essay ("memoir") with a theory of the propagation of elastic waves in solids. In his memoir, he states that an earthquake would produce two different waves: one having a certain speed a {\displaystyle a} and the other having a speed a 3 {\displaystyle {\frac {a}{\sqrt {3}}}} . At a sufficient distance from

777-447: The curl of this equation and applying vector identities, one gets ∂ t 2 ( ∇ × u ) = μ ρ ∇ 2 ( ∇ × u ) {\displaystyle \partial _{t}^{2}(\nabla \times {\boldsymbol {u}})={\frac {\mu }{\rho }}\nabla ^{2}\left(\nabla \times {\boldsymbol {u}}\right)} This formula

SECTION 20

#1732851283873

814-537: The divergence of seismic wave equation in homogeneous media, instead of the curl, yields a wave equation describing propagation of the quantity ∇ ⋅ u {\displaystyle \nabla \cdot {\boldsymbol {u}}} , which is the material's compression strain. The solutions of this equation, the P waves, travel at the speed α = ( λ + 2 μ ) / ρ {\textstyle \alpha ={\sqrt {(\lambda +2\mu )/\rho }}} that

851-832: The nabla operator notation of vector calculus , ∇ = ( ∂ 1 , ∂ 2 , ∂ 3 ) {\displaystyle \nabla =(\partial _{1},\partial _{2},\partial _{3})} , with some approximations, this equation can be written as ρ ∂ t 2 u = ( λ + 2 μ ) ∇ ( ∇ ⋅ u ) − μ ∇ × ( ∇ × u ) {\displaystyle \rho \partial _{t}^{2}{\boldsymbol {u}}=\left(\lambda +2\mu \right)\nabla \left(\nabla \cdot {\boldsymbol {u}}\right)-\mu \nabla \times \left(\nabla \times {\boldsymbol {u}}\right)} Taking

888-615: The Pacific plate. The earthquake's location and focal mechanism are consistent with the earthquake having occurred as underthrusting of the Australia/Woodlark/Solomon Sea plate beneath the Pacific plate, as part of the broader northeast-directed subduction process. The length of faulting was estimated to be about 260±50 km. The Solomon Islands arc as a whole experiences a very high level of earthquake activity, and many shocks of magnitude 7 and larger have been recorded since

925-538: The Solomon Islands and Papua New Guinea. Separately, the Red Cross has issued an appeal for US$ 800,000. The remoteness of some villages meant that aid did not reach them until several days after the tsunami occurred. However, the Associated Press reported on 6 April that Gizo's airport had reopened, easing the delivery of supplies. A Taiwanese fishing boat ran aground on coral reefs while delivering supplies, but it

962-565: The arrival of a huge wave that had washed away several houses and come inland about 200m. This information was passed on by telephone to the Hawaii-based Pacific Tsunami Warning Center who then upgraded their warning to an "expanding regional alert". This was achieved before the 35-minute arrival time of the wave for the capital Honiara, which in the event proved non-destructive. At least fifty-two people were reported to have been killed and sixty reported missing when

999-497: The coast were closed, while many evacuated to higher ground. However, as the epicenter was close to the Solomon Islands, the tsunami hit before the Hawaiian Pacific Tsunami Warning Center released the warning. As high-magnitude ocean waves propagate at high speeds close to 25 meters per second, they traversed the 55-kilometer distance from the epicenter to Gavo in less than 20 minutes. The S waves from

1036-585: The coastal waters as well as an uncanny capacity to sense the impeding danger. Some of the historic cultural practices on Simbo are referenced in The Ghost Road , a novel by Pat Barker about World War I . The author used the research of Arthur Maurice Hocart and the psychoanalyst William Rivers . This Solomon Islands location article is a stub . You can help Misplaced Pages by expanding it . 2007 Solomon Islands earthquake The 2007 Solomon Islands earthquake took place on 2 April 2007, near

1073-531: The early decades of the twentieth century. The 2 April earthquake, however, nucleated in a 250 kilometre-long segment of the arc that had produced no shocks of magnitude 7 or larger since the early 20th century. A tsunami warning was issued for the South Pacific Ocean , and advisories issued for Japan and Hawaii. The Australian Bureau of Meteorology issued a warning for Australia's eastern coast, from Queensland's Barrier Reef to Tasmania , and beaches along

1110-465: The earthquake shook the ground and alerted the population, allowing many to flee to high ground before the wave struck. From Honiara, one of the first warnings came from the People First Network 's Simbo email station, situated close to the epicentre. PFnet's Technical Advisor David Leeming relates that 20 minutes after the earthquake, Nickson Sioni from Simbo came on the (HF) radio and announced

1147-625: The exposure of the reefs are a normal part of island building and that careful wildlife management can preserve the reefs that remain. Australia committed to contribute an initial AUD$ 3 million in emergency aid, later increased to 5.7 million as of June 2007. New Zealand gave NZD$ 950,000 during the initial relief period, and committed NZD$ 7.5 million over two years to reconstruction, as of July 2007. The United States contributed US$ 250,000 in aid. Taiwan contributed US$ 214,000 and shipment of 1,000 kg of rice. France has also airlifted supplies via New Caledonia . The United Nations established

Simbo - Misplaced Pages Continue

1184-408: The fact that they are the second type of wave to be detected by an earthquake seismograph , after the compressional primary wave, or P wave , because S waves travel more slowly in solids. Unlike P waves, S waves cannot travel through the molten outer core of the Earth, and this causes a shadow zone for S waves opposite to their origin. They can still propagate through the solid inner core : when

1221-489: The largest of which had a magnitude of 6.2. The Australia , Woodlark , and Solomon Sea plates converge to the east-northeast or northeast against the Pacific plate with velocities of 90–105 millimetres/year. Along much of the plate boundary between the Pacific plate and the Australia/Woodlark/Solomon Sea plates, relative plate-motion is accomplished principally by subduction of the Australia/Woodlark/Solomon Sea plates beneath

1258-500: The medium of propagation is linear, elastic, isotropic, and homogeneous, this equation can be rewritten as μ = ρ β 2 = ρ ω 2 / k 2 {\displaystyle \mu =\rho \beta ^{2}=\rho \omega ^{2}/k^{2}} where ω is the angular frequency and k is the wavenumber. Thus, β = ω / k {\displaystyle \beta =\omega /k} . Taking

1295-703: The provincial capital of Gizo on Ghizo Island , in the Solomon Islands . Its magnitude was estimated at 8.1 on the M w scale, and 7.8 on the M s scale. The tsunami that followed the earthquake killed 52 people. According to the USGS, the earthquake was recorded around 7:39:56 a.m. local time ( UTC+11 ). The focus was 10 km (6 mi) deep and 40 km (25 mi) south southeast of Gizo township on New Georgia Islands in Western Province . There were numerous aftershocks,

1332-416: The source, when they can be considered plane waves in the region of interest, the first kind consists of expansions and compressions in the direction perpendicular to the wavefront (that is, parallel to the wave's direction of motion); while the second consists of stretching motions occurring in directions parallel to the front (perpendicular to the direction of motion). For the purpose of this explanation,

1369-485: Was successfully evacuated by a United States Navy helicopter. The boat's crew managed to free the vessel from the rocks a few days later. Francis Billy Hilly , the MP for Simbo Island where 10 people died, said on 8 April that those who had previously resisted resettlement away from the island's active volcano were reconsidering their options. The national government may also relocate islanders away from low-lying areas pending

#872127