Magnitude 7.2 Earthquake Rocks Turkey

It had been estimated that more than 600 people were crushed dead and more than 2.600 injured in a strong earthquake that rocked eastern Turkey. On October 23, 2011, the earthquake registered a magnitude of 7.2 and hit the Van province that was in close proximity to the Iranian border.   USGS revealed that the epicentre of the earthquake was 16 km north-east of Van in eastern Turkey.  After the main quake, approximately 1,400 aftershocks struck the region. One of the major tremors included the 5.6-magnitude quake that shook the Van province on November 9, 2011.
Turkey is subject to frequent earthquakes as it sits atop major geographical fault lines. Two earthquakes with magnitudes of more than 7 occurred in 1999, killing more than  20,000 people in the densely populated areas in the north-west territories of Turkey. The October 23, 2011 earthquake was triggered by the collision of the Arabian and Eurasian plates. The Arabian plate converges with Eurasia at a rate of 24 mm/year.













The strongest impacts of the quake were felt in Van and neighbouring towns. Serious damage and causalities were witnessed in the Celebibag district. 2,262 buildings were destroyed in the Turkish quake. Collapse of schools remain a key concern in the Turkish quakes and draws the attention of government agencies. As October 23 was a Sunday, the impacts of the Turkish quake could be more catastrophic if the earthquake were to strike on Monday morning instead. The tremors in the aftermath of the 7.2-magnitude main quake further weakened building structures, and even brought down two hotels and 16 other buildings.
One of the hotels that collapsed was Bayram Hotel, Van’s most reputable hotel that was at least 40 years old. It was one of the hotels that accommodated journalists and aid workers involved in recovery efforts following the main quake. Since the onset of the October 23 main quake, many residents had been putting up in tents despite the cold weather. This was so due to the fear of returning to their own homes.  

The quake had also exposed problems such as the paucity of earthquake-safe buildings. According to the national chamber of mechanical engineers, two out of three buildings in Turkey were illegally constructed without permits or supervision. It was also revealed that of the 18 million buildings in Turkey, 40% were not earthquake safe. Such a problem was sustained by greed and incompetence among builders, coupled with corruption and the lack of supervision by the relevant authorities.
Such a problem was further aggravated by the lack of awareness among the people of the safety of their current residences. The phenomenon of people residing atop earthquake fault lines and not requesting for safety inspection could be attributed to poverty and insufficient legislation. Furthermore, fatalism is embedded within the Anatolia culture, viewing quake occurrences as an act of God and that people could not exert influences on their own lives.
Authoritarian relations between the state and citizens had caused the Turks to develop dependence on the state instead of taking initiatives for their own safety. Many Turks perceive that the state would have to come in to intervene in issues pertaining to earthquake safety. Given the inherent mindset among the people, consequences caused by quakes would remain disastrous.
 
References:

• http://earthquake-report.com/2011/10/25/new-insights-into-the-october-2011-van-turkey-earthquake-detailed-analysis-by-the-cedim-forensic-earthquake-analysis-group/
  
• http://www.huffingtonpost.com/2011/11/11/turkey-earthquake-2011-hotels_n_1088614.html
  
• http://www.dailymail.co.uk/news/article-2059592/Turkey-earthquake-2011-25-dead-second-quake-hits-south-Van.html
  
• http://www.bbc.co.uk/news/world-europe-15425268
  
• http://www.guardian.co.uk/world/2011/oct/23/earthquake-hits-eastern-turkey
  
• http://www.nytimes.com/2011/11/03/world/middleeast/03iht-M03-TURKEY-QUAKE.html?_r=2&pagewanted=all

Sendai Earthquake-Tsunami 2011

Overview

A magnitude 8.9 earthquake struck about 400 km northeast of Tokyo at 0546 GMT (1446 Japanese local time), on March 11, 2011. The shallow depth of the earthquake was registered at 24 km deep (USGS, 2011), bringing detrimental impacts. The earthquake was found to be the fifth largest in the world since 1900 and it is the most devastating earthquake to hit Japan since official records were kept in the late 1800s. The magnitude 8.9 quake  triggered about 10 m tall of tsunami waves, coupled with more than 160 aftershocks and many of them registered a magnitude of more than 6.0. Japan’s Kyodo news agency reported a 10 m tsunami wave striking the Sendai port, driving ships, vehicles and other debris inland. Many villages and cities along a 2,100 km stretch of coastline were devastated by violent tremors that reached as far as Tokyo, which is hundred of kilometres from the quake’s epicentre.

Global Impacts

The Pacific Tsunami Warning Centre reported tsunami waves with amplitudes (peak and trough of waves) of up to 7.3 m on the coast of Japan. Even out in the open ocean, the specialist warning buoys recorded wave amplitudes of 1 m. Thus, waves would have travelled across the Pacific, towards the Philippines, Hawaii and even recorded on the landmasses of North and South America. Tsunami waves began hitting the western coast of United States (US) and communities from southern Oregon to Los Angeles braced themselves for swells and rough sea conditions. The harbour and dock area of Crescent City, California, was entirely damaged but the tsunami impacts on the US were blunted as it struck during the lowest tide point of the day.

Devastation in Japan

Thousands of residents living in the vicinity of Fukushima nuclear plant have been ordered to evacuate after the earthquake as nuclear officials reported that pressure within a boiling water reactor was running higher than normal after the failure of the cooking system. 11 units of thermal power plants were shut and 22 hydro plants were halted. Japan’s Fukushima No.1 nuclear power plants exploded on March 12, 2011, located about 250 km northeast of Tokyo. Residents in the vicinity were  strongly encouraged to remain indoors and fears of a meltdown were ignited.

More than 10% of Japan’s populace were left without electricity and and rail service in Tokyo was suspended overnight and elevated highways were shut. Thousands of commuters had to spend their nights in shelters with the breakdown  in transport networks and services. Air travel was also disrupted by the quake, leaving 13,000 people stranded in the Narita airport  and 10,000 were stuck at the Haneda airport.

As of March 12, 2011(midnight Japanese local time), the official death toll exceeded 687, leaving 784 people missing and 1,128 injured. Between 200 and 300 bodies were found along the coast of Sendai, the largest city in the proximity of the quake’s epicentre. Since the occurrence of the quake, more than 1 million households do not have water access and they are mainly concentrated in northeast Japan. About 5.57 million households experienced were cut off from power supplies.

Strong waves devastated Japan's Miyagi and Fukushima prefectures, damaging dozens of coastal communities. A 10 m tsunami wave struck Sendai, inundating farmlands and sweeping cars across the airport’s runway. Surges of debris-filled water reached far inland, sweeping off ships, cars and houses on its path. The tsunami roared over embankments, washing anything in its path inland before reversing directions and carrying the cars, homes and other debris out to sea. In Iwate Prefecture, most areas of the coastal city of Rikuzentakata were submerged and tsunami waters reached up to the third floor of the city hall. A large fire erupted at the Cosmo oil refinery in Ichihara city in Chiba prefecture and burned uncontrollably with thick flames whipping into the sky. Fires also remained a problem in residential areas such as Kesennuma in Miyagi prefecture, which battled 3 large-scale fires. Fires could be attributed to the rupture of gas pipes. About 3,400 buildings were already destroyed. Car manufacturers Toyota Motor Corp., Nissan Motor Co. and Honda Motor Co. all planned to suspend production at Japanese plants on Monday (14th March) due to difficulties of obtaining parts.

 

 References

• The Straits Times (March 12,2011). ‘Monster Tsunami’.
• The Straits Times (March 12,2011). ‘Wall of water leaves trail of destruction’.
• The Straits Times (March 12,2011). ‘Massive disruption nationwide’.
• The Straits Times (March 13, 2011). ‘Nuclear Scare’.
• The Straits Times (March 13, 2011). ‘Cries heard from under the rubble’.
• http://www.seisvol.kishou.go.jp/eq/eng/fig/info.html
• http://www.bbc.co.uk/news/science-environment-12710999
• http://www.bloomberg.com/news/2011-03-11/tokyo-buildings-shaken-by-7-9-earthquake-highest-tsunami-warning-issued.html
• http://edition.cnn.com/2011/WORLD/asiapcf/03/11/japan.quake/index.html
• http://www.thestar.com/news/world/article/953035--explosion-at-japan-nuclear-plant-triggers-fear-of-meltdown?bn=1
• http://www.bbc.co.uk/news/world-asia-pacific-12709598
• http://www.foxnews.com/world/2011/03/11/massive-7-magnitude-earthquake-strikes-japan/
• http://www.news.com.au/world

• http://www.latimes.com/news/nationworld/world/la-fgw-japan-quake-death-toll-20110313,0,5963738.story 

Impacts of Christchurch Earthquake

A magnitude 6.3 earthquake struck Christchurch of New Zealand during the lunchtime period, 12.51 pm, on February 22, 2011. New Zealand rescuers worked through the night to save trapped survivors after a catastrophic earthquake that left 400 people dead or missing. In order to rescue survivors trapped under the rubble, rescuers had to amputate their limbs to bring them out of the ruins of the buildings. New Zealand Prime Minister John Key had declared the earthquake event as a national emergency as it is the worst natural disaster in 80 years. The current earthquake was the deadliest to strike New Zealand since the 1931 tremor that took a way 256 lives. It followed six months after a magnitude 7.0 earthquake that weakened buildings in Christchurch on September 2010. Christchurch is New Zealand’s second largest city.

Despite the smaller magnitude of the 2011 quake as compared to the magnitude 7.0 earthquake in 2010, the 2011 earthquake was more destructive as it was closer to the city centre of Christchurch and much closer to the Earth’s surface. This is so as the earthquake occurred at a shallow depth of 5 km during the lunch hour when Christchurch was at its busiest. In comparison, the magnitude 7.0 earthquake in September 2010 had the epicentre occurring around 40 km west of the city, which proceeded to rupture  away from major built-up areas.

The tremor also sent the spire of Christchurch Cathedral, a landmark of the city centre, toppling into the square below. The area outside the cathedral resembled that of a ‘warzone’. The military had already been roped in to facilitate the rescue operations and the New Zealand government has already accepted specialist aid from Australia. Power supplies were disrupted and a series of aftershock of magnitude 5.0  further devastated the city and impeded rescue operations. New Zealand is subjected to more than 14,000 earthquakes annually, of which around 20 of them possessed a magnitude of more than 5.0.  This is so as New Zealand sits on the Pacific Ring of Fire, the zone subjected to frequent events of earthquakes and volcanic eruptions. New Zealand is straddled between 2 major plates: the Pacific and Indo-Australian plates. It had been estimated that the 6.3 magnitude earthquake could bring about losses of up to $12 billion, the most expensive natural disaster following the loss of $19.9 billion when Hurricane Ike struck the United States in 2008.

 

References:

• http://www.vancouversun.com/news/Nearly+dead+missing+Zealand+quake/4322111/story.html
• http://www.bbc.co.uk/news/world-asia-pacific-12533291

Fault System of New Zealand

A fault line is a resultant fracture caused by the movement of the Earth's crust. Major faults in New Zealand would include the North Island Fault System and the Alpine Fault.

The North Island Fault System is a major plate boundary found in the North Island and is subject to constant stress, generated by the movement between the Australian and Pacific plates.At the North Island, the Pacific plate is moving towards and subducted beneath the Australian plate. Deep earthquakes at North Island form a well defined seismic zone.

The South Island houses the Alpine Fault, which carries most of the plate boundary strain. Along the Alpine Fault, plates are sliding past each other and also moving towards one another. The main part of South Island is thrust over the Australian Plate on a bearing of about 250 degrees. The compressional forces result in the uplifting of Southern Alps at a rate hovering around 7 millimetres per year and subsequently forming a high, elongated mountain range that runs parallel to the Alpine Fault.

Records of notable shallow earthquakes in New Zealand

Earthquake in New Zealand

An earthquake struck New Zealand's South Islands on September 3, 2010. The epicentre was 55km, northwest of Christchurch at a depth of 12km, generating widespread damage and power failures.

Damages to buildings due to the magnitude 7.0 earthquake

Christchurch is New Zealand's second largest city with a population size of 386,000. The 7.0 magnitude earthquake brought about a declaration of state emergency in Christchurch. As New Zealand is seated at the southern tip of the Pacific Ring of Fire and is the zone where the Pacific plate converges with the Indo-Australian plate. New Zealand is subjected to approximately more than 14,000 earthquakes annually, whereby 20 of them exceed a magnitude of 5.0. The last deadly earthquake that hit New Zealand was one measuring 7.1 magnitude on the South Island's western coast.Christchurch International Airport was shut as a precautionary measure and several strong aftershocks were felt after the main shock.

Volcanic Structures

Volcanic plugs are formed as a result of congealed magma and fragmented volcanic rock materials in the feeding conduits of a volcano upon the cessation of volcanic activity.Upon the ceasing of volcanic eruptions, the central conduit of the volcano would be plugged with hard, solidified lava.
They are believed to lie atop a body of magma which could be in the liquid or completely solid form, depending on the state of activity of the volcano. They are commonly funnel-shaped and taper downwards into bodies that are elliptical in shape or elongated, disc-like forms.
If the volcano is composed of weaker materials, erosion is able to remove weaker materials on the volcanic cone, leaving the resistant volcanic conduit standing tall as a volcanic plug.



Devils Tower National Monument, Wyoming in USA is a volcanic plug that rises 386m above the surrounding terrain and the summit is 1,558m above the sea level.

Craters are found near the summit of most volcanoes. A caldera is a funnel-shaped depression opening upwards where volcanic gases, ash and lava are ejected from the volcano. A crater is less than 2km in diameter and formed via outward explosion.

However, many shield volcanoes have a much larger depression known as a caldera, which is am elongated crater at the summit of the volcano.  Calderas are circular, steep walled basins that my be several kilometres or more in diameter. They are the resultant features of the partial emptying of a magma chamber and due to inward collapse. Rapid ejection of magma during a large lava or tephra eruption can cause the emptying or partial emptying of the magma chamber. The unsupported roof of the chamber would then succumb and collapse under its own weight. The caldera may later hold a lake when the caldera cools, enabling snow and rain to accumulate, such as Crater Lake in Oregon, USA and Lake Toba in Indonesia.Subsequent events of minor eruptions can result in the production of small volcanic islands within the lake.



Crater Lake in Oregon occupies a circular caldera 8km in diameter and was attributed to a great eruption by Mount Mazama.





The figure shows the formation of Crater Lake due to the eruption of Mount Mazuma in 5677 B.C.E, which emptied a substantial volume of viscous magma, leaving a void inside the weakened mountain and the eventual failure of the unsupported top into the emptied magma chamber.













With reference to:

• Hyndman, D. (2006) Natural Hazards and Disasters
• Abott, P.L. (2007) Natural Disasters
• http://pubs.usgs.gov/dds/dds-72/site/intro.htm

Volcanic Eruption in Iceland

 

The footage above shows the process of the Icelandic volcanic eruption in April 2010, which is the most recent volcanic eruption across the globe. The Eyjafjallajoekull volcano had been dormant for the past 200 years  and it sits above glaciers around the Westman islands, off Iceland's south-western coast.

 

Volcanoes in Iceland are due to the spreading centres along the Mid Atlantic Ocean and the divergence between the North American and Eurasian plates. The Mid Atlantic Ridge is the most volatile zone between the Eurasian and North American continental plates, which experiences significant occurrences of volcanic eruptions and earthquakes. The most typical Icelandic eruptions are lava eruptions where lava is ejected out of long fractures.

                                                                           

Earthquake in Haiti 2010

Poverty stricken Haiti was badly devastated by a 7.0 magnitude earthquake in January 2010, over its capital Port-au-Prince. The epicentre of the quake was only 16km from Port-au-Prince, which houses around 4 million people.Many buildings including schools, churches and even the Parliament Building, resulting many casualties as people are trapped under the debris.