2009 Pacific Tsunami

2009 Pacific Tsunami

1. Natural Processes

   • Tectonic
     • 1. Magma, heated by the earth's core (5000°C) moves in convection currents in the mantle.
     • 2. Convection currents cause the Pacific Plate to subduct west below the Indo-Australian Plate at a rate of 86mm/yr, creating the Tonga Trench
     • 3. Friction and pressure built up at the Tonga Trench, causing two earthquakes (Mw = 8.1) 18km deep to occur on the outer rise of the Pacific Plate, 6.48am local time. A piece of the Pacific Plate flicked upwards 14m.
   • Oceanic
     • 4. Vast quantities of seawater were displaced by the fault rupture. Waves radiated out from the epicentre of the quake at a rate of 800km/hr
   • Coastal
     • 5. As the waves scoured the sea floor their wave length decreased and wave height increased. 2-3 waves collided with Samoa 10 minutes after the initial earthquake

2. Effects

   • Natural
     • Samoa
       • Coastal Erosion
         • Caused the beach profile to drop up to 1.5m at Lalomano
       • Coral Reef
         • severely damaged when waves carrying sand and silt were forced against them
       • Sea Grass Beds
         • Sea Turtles who feed on sea gras were washed ashore
       • Landslides
         • Occured where the tsunami waves hit the steep cliffs. At Lalomanu a 15m landslide occured
       • Coconut trees
         • Uprooted and exposed at Poutasi. Trees were bent and broken
       • Salinisation
         • Prevented plants from growing at Manoa
       • Maximum runup height was 14m at Lep
       • Bluff Erosion occured at Aufaga
       • Coastal Erosion
         • In front of Coconuts resort on South East coast of up to 1m
     • American Samoa
       • Soil and sand was inundated by 2m of seawater. Soil became covered in silt and salt.
       • Salinisation
         • This means that the soil becomes very salty. The salt is left behind when the tsunami wave recedes. Salinised soil is very hard to grow crops like taro on.
       • Scouring
         • occured along the beachfront and 2m scarps were formed.
       • Mangrove Forests
         • Sand and other loose material such as boulders were forced against the mangrove forest as the wavepproached and retreated.
       • Flooding 500m up the Vaipito River
     • Tonga
       • Coastal Erosion
         • caused 4m of sand to be removed leaving the dry coralexposed below.
       • Debris
         • 4m high piles od debris
       • Forest
         • Tafahi forest was destroyed(6% of the island's total land area. All tree roots were uprooted or snapped at the base.
   • Cultural
     • Tonga
       • Death
         • 9 dead. 7 were riding in a pick up truck parallel to the coastline.
       • Infrastructure
         • 50% of all houses were destroyed.
         • Water and sanitation systems completely destroyed and filled with silt.
         • Local prison housing 10 people was destroyed and the prisoners were evacuated.
       • Healthcare
         • Healthcare facilities badly damaged.
       • Agriculture
         • Agriculture and fisheries inn the area damaged, many villagers were fishermen and planters of taro and root crops
       • Water
         • fresh water springs were infiltrated with seawater.
     • Samoa
       • Mental Health
         • Studies report Post Traumatic Stress Disorder (PTSD), fear of the sea, difficulty sleeping and wanting to move inland.
       • Infrastructure
         • Wooden buildings were torn from their foundations (concrete church remained standing in Lepa).
         • Taufua beach fales reduced from 100 to none.
         • Damage to community buildings, roads, power lines and water supply along the coastline was estimated to cost NZ$53 million.
         • 119 villages wiped out.
       • Tourism
         • 18 accommodation sites were wiped out including high end resorts such as Coconuts and Sinalei.
         • Samoa depends on Tourism for 75% of its income.
       • Death
         • 149 people were killed. A mother at Taufua saw her 3 babies swept away.
         • On the 8th of October a national funeral was held for the victims at Apia Park.
     • American Samoa
       • Infrastructure
         • Water system damaged and water supply disrupted. Tanker trucks had to bring in fresh water. Residents warned to boil until safe.
         • Main street in Pago Pago flooded, cars overturned, shops damaged.
         • Main electricity generator in Satala destroyed.
       • Displacement of people
         • 220 people moved to 7 shelters across the island.
         • Looting was observed in Pago Pago.
       • Economy
         • It cost $2 million to remove debris from the island.
         • The population here is reliant on fishing. Fish are caught for processing and canning in American-owned factories. Canned tuna accounts for almost all of American Samoa export income.
         • Cleaning of the Satala power plant was estimated at $48 million.
       • Death
         • 34 dead

3. Vulnerability

   • Samoa
     • Relief
       • flat coastal plains backed by steep cliffs causing back wash, 15m landslides and 1.5m of coastal erosion.
     • Awareness
       • Tsunami evacuation signs were present but did not tell people where to go.
     • Transport
       • roads ran parallel to the coastline so people could not get away. 7 people were killed in a pick-up truck.
     • Infrastructure
       • wooden fales were vulnerable to damage.
     • Coral Reef
       • fragile ecosystem easily damaged by wave action.
   • American Samoa
     • Population Distribution
       • concentration of population on flat coastal land close to ocean resources, which is vulnerable to coastal erosion.
     • Relief
       • the shape of the harbour caused the wave height to increase from 2m to 8m.
     • Relief
       • low lying coastal land was vulnerable to salinisation.
   • Tonga
     • Relief
       • highest point only 157m, allowing tsunami to travel 600m inland (causing destruction of entire forest 6% total land area)
   • Alarm
     • Pacific Tsunami Waning Centre (Hawaii) was 16mins late in sounding alarm.
   • Technology
     • Local radio stations broadcasted alarm but many did not hear it.
   • Location
     • the islands are located in the Pacific Ring of Fire, 200km radius from the Tonga trench.

4. Response

   • Short Term
     • Individuals
       • Panic!
       • Got into cars
       • Otele Samuelu (Lalomanu) When he felt the quake he rushed to warn tourists at the Taufua Beach Fales where he worked.
       • Tried to run to high ground e.g. Lalomanu
       • Locals and tourists tried to search for bodies
       • Massive clean up effort in the days following the quake
       • New Zealanders with family members missing travelled to try and find them
     • Communities
       • Communities banded together
       • Held funerals e.g. Taufua family held a funeral Sept 30th for their 14 family members that died.
       • Communities stuck together and moved into shelters together.
     • Aid Organisations
       • Red Cross sent first aid kits and volunteers set up shelters. Used $1.4 million from NZ donations to do this.
       • Oxfam sent an Emergency team who helped set up fresh water supply by collecting rainwater. Used $4.4 million from NZ donations to do this
     • Governments
       • US President Barack Obama declared major disaster in American Samoa, gave funding to safety and rescue teams; sent drugs, food and water
       • John Key visited W. Samoa. Sent an air force Orion to search for bodies. Sent Hercules with medical supplies. Sent scientists from NZ Civil Defence
       • Government of Samoa provided funding for families. Evacuated Apia immediately after Tsunami.
   • Long Term
     • Individuals
       • Choosing to build strong “European- style” homes
       • Choosing to build reinforced vegetable gardens in protected areas to replace lost crops
     • Governments
       • Long term funding from NZ government for researh into the effects of the Tsunami in Samoa
     • Aid Organisations
       • Red Cross has an education awareness program about Tsunamis.
       • Oxfam continues to provide support to 2500 people who lost their livelihoods. They do this by teaching them to grow new cash crops
     • Communities
       • Entire communities moved inland (e.g. Saleapaga)
       • Monument build at Saleapaga to honor those who died
       • Strong social and religious fabric has allowed people to recover quickly
       • Escape routes for communities being built up steep cliffs at Lalomanu