I chose to do my case study on the 2011 Christchurch earthquake in New Zealand. I chose it because I have always been interested in Liquefaction and the damage that is causes to infrastructure. The boundary between the subducting oceanic plate and the Australian plate runs right through the middle of New Zealand. New Zealand is part of the Ring of Fire. The area is highly tectonically active so New Zealand receives a lot of earthquakes. The Christchurch earthquake occurred at 12:51 PM New Zealand time on February 22, 2011. The focus of the earthquake was very close to the surface and it had a magnitude of 6.3. The earthquake was powerful enough to generate its own aftershocks, even though it was technically an aftershock a larger but less destructive earthquake six months previously. The earthquake was caused by a previously unknown fault line that was 6 km from the center of Christchurch. The type of faulting that caused the earthquake is called reverse faulting. The secondary hazard besides the actual earthquake itself is the liquefaction that occurred as a result of the earthquake. The liquefaction destabilize the foundations of the buildings and caused them to partially sink into the ground or collapse. The liquefaction deposited thousands of tons of silty sand all over Christchurch. The liquefaction actually caused more damage than the shaking from the earthquake. 185 people died in the earthquake and 7000 people were injured.
Over the years New Zealand has taken many steps to mitigate the damage caused by earthquakes. They have retrofitted their bridges, and lifelines to hopefully withstand earthquakes. They also practice earthquake drills in schools and teach the children the safest places to be during an earthquake. The problem I caused the most damage was the development of residential neighborhoods in areas that they knew had a high risk of liquefaction. When the earthquake occurred most of the houses in these areas were destroyed from a combination of the liquefaction and the shaking from the earthquake.
Christchurch is still rebuilding from the earthquake and may have completed about half of the Christchurch central recovery plan. It focuses on a few key projects that will help revitalize Christchurch. Christchurch central business district was mostly destroyed so during the rebuilding process they have changed the Central business district hopefully for the better. The government has also bought out the houses in the areas with high liquefaction and there are plans to turn the area into a park.
Christchurch was not caught completely unawares by the liquefaction that occurred during the 2011 earthquake. The earthquake that had occurred in September of the previous year had minor liquefaction and scientists knew that liquefaction was possible in the area. Christchurch was prepared to handle an earthquake but they were not prepared for liquefaction.
Since the Christchurch earthquake, New Zealand’s economy has been bolstered by a booming construction economy. Other earthquakes have hit Christchurch in the last five years and they seem to be slowly rebuilding.
Multiple tornadoes were spotted today in Arkansas and Georgia as a serve thunderstorm continues to make its way across the south today. One EF0 tornado passed through Yell county, Arkansas with sustained winds of 85 mph. “The tornado’s path was half a mile long and it measured about 50 yards in length.” The tornado caused some damage but most the knocked down trees and damaged homes were the result of stronger straight line winds. Two other tornadoes occurred in Montgomery and Pike counties. The tornadoes knocked over trees and damaged power lines and homes. One person was injured when a tornado touched down in Talbot County, Georgia. Three homes were damaged and a large amount of trees were snapped in half or knocked down. A small EF0 tornado touched down in Holdenville, Oklahoma Thursday evening with sustained winds of 68-85 mph.
A squall of severe thunderstorms are moving through Arkansas tonight. The storm has produced wind gusts up to 70 mph. The storm is still moving through Arkansas, but so far it has damaged houses, knocked down trees, produced hail, and spawned a possible tornado. It has also caused roads to close because of flooding. The storm also has a significant amount of lightning.
Flooding from the heavy rain has caused a large hole to open in the middle of Blue Springs Road in Arkansas. The large hole has caused the road to close and they have put barriers in front of the hole to prevent anyone from coming to close.
A severe thunderstorm passed through the D.C. area late on Friday. The small intense thunderstorm did not last long but it did cause a decent amount of damage. As the thunderstorm quickly moved through the area it produced heavy rain, quarter sized hail, strong winds, and lots of lightning. About 4,000 homes and business lost power Friday evening when the thunderstorm knocked down power lines. The hardest hit area were Takoma Park, Maryland and part of D.C. Falling trees caused damage to property and smashed cars. Lucky only minor injures were reported. Two people had to be rescued from Rock Creek State Park because of rushing water.
Severe thunderstorms are causing hail, possible tornadoes, and damaging winds in Arkansas and Oklahoma. The thunderstorms were predicted to have straight line winds, large hail, and possibly create tornadoes. The severe thunderstorms will pass through Arkansas and Oklahoma in two rounds. The first set of storms was moving through Arkansas as of 2:00 pm this afternoon. So far the storm has knocked down tree branches and caused flooding. The second round of thunderstorms will pass through Arkansas late this afternoon and evening and will be gone by Saturday morning. Wind gusts up to 70 mph are expected in addition to 1 to 3 inches of rain in certain areas. Flood warning have also been issued for central Oklahoma. Last night and earlier today severe supercell thunderstorms caused damage in Texas. The thunderstorms are part of a multiple day serve weather event that is crossing the south this weekend.
Before Cyclone Cook made landfall in New Zealand at the Bay of Plenty on Thursday it was predicted to be the worst cyclone to hit New Zealand since 1968. Prior to the Cyclones landfall on the Northern Island, New Zealand authorities declared a state of emergency and people fled their homes. The expected path of the cyclone was forecasted to pass right over the islands. The actual track of Cyclone Cook turned away from New Zealand. Since the cyclone was moving so fast the rain did not last long. Instead New Zealand dodged the bullet and the worst of the storm passed by out at sea.
When Cyclone Cook made land fall at 6:30 PM New Zealand time it caused power outages, extensive flooding, landslides, uprooted trees and caused road closures. Horizon Energy says that its customers should expect to remain without power for 3 days. Luckily there was only one casualty and two people were sent to the hospital. On the South Island in Canterbury Christchurch sustained some of the most extensive flooding due to the Heathcote River overflowing its banks. Christchurch is the area that I am doing my case study for which is why this caught my attention.
The Philippines experienced a earthquake swarm this afternoon at about 3 pm Philippines time. The earthquakes occurred on the island of Luzon near the city of Batangas. Luzon is the largest and most populated island in the Philippines. The third earthquake to hit was the strongest measuring 5.9 mm. The USGS said the quake was at a depth of 42.7 km (27 miles). After the earthquakes the residents fled the coastal city for higher ground because they feared the earthquake could produce a Tsunami. “Residents in the coastal villages in two towns have evacuated to safer ground after the earthquakes,” Lito Castro, head of the provincial disaster council, told local radio. “The people were afraid the earthquakes would generate a tsunami.” I find this fact interesting because if the earthquake occurred in a non coastal location peoples reaction to the earthquake would possibly be different. The people of the Philippines are aware of the of earthquakes causing tsunamis so they immediately know to flee to higher ground. ” The area is still experiencing aftershocks. Fortunately, so far there are no reports of casualties.
A mudslide occurred overnight in Bogata, Colombia. The mudslide was caused by, “Sudden, heavy rainstorm happened around midnight in Mocoa, a provincial capital of about 40,000 tucked between mountains near Colombia’s southern border with Ecuador.” Three rivers burst their banks and sent muddy water rushing through the town in the middle of the night sweeping away houses and uprooting trees. It also carried larger rocks and sediment surging down the mountain toward the town. “Many residents did not have enough time to flee. An avalanche of water from three overflowing rivers tore through a small city in Colombia while people slept, destroying homes, sweeping away cars and killing at least 193 unsuspecting residents.” The red cross says that 202 people are injured and 220 people are missing. The president of Columbia has declared a state of emergency. They are still looking so the death toll will probably rise.
An out break of severe weather last night and this morning in Texas and Oklahoma caused lots of damage. The storm flooded roads and knocked out power for over 200,000 people in northern Texas. The thunderstorm also produced damaging wind sheer that knocked over trees and caused property damage. The same storm also produced baseball size hail that shattered car wind shields casing people to be sent to the hospital. Along with the flooding, hail, and wind sheer the thunderstorm also spawned at least 14 tornadoes. Which is very impressive. All of the tornadoes were in Texas, so the damage sustained in Oklahoma was not a tornado but due to the wind sheer over 95 mphs. So far there has only been one person reported dead.
Earlier today a 6.6 mm earthquake occurred off of Russia’s east coast near the Kamchatka peninsula at 11:00 am EST (4 am UK time). The focus of the earthquake was at a depth of 22.8 km. There was the possibility of a 1.5m Tsunami but Russia’s emergencies ministry later recalled the warning.