A volcano is a rupture or opening on the surface of the earth where magma breaks through releasing gas, ash, lava and molten rock.  Magma mostly comes from the asthenosphere below the lithosphere.  The asthenosphere is weaker than the lithosphere and close to its melting point. The depth and pressure from above keeps the rocks in the asthenosphere from melting.  When two plates spread, the lithosphere becomes weaker and does not exert as much pressure on the asthenosphere below, resulting in decompression melting and the forming of magma which rises to the surface.  Most volcanoes are located in divergent or convergent plate boundaries.  In subduction zones, volatiles are released as one plate moves under the other.  Volatiles are chemical compounds like water, carbon dioxide and sulfur dioxide that when released can lower the melting temperature of rocks in the asthenosphere causing the magma to rise.

     Madagascar has five volcanoes.  They are Ambre-Bobaomby, Ankaizina, Ankaratra Field, Itasy Volcanic field and Nosy-Be.  All of these volcanoes are dormant.  The last eruption occurred in 6050 BC in the Itasy Volcanic Field.  Since there is no active volcanic activity now or in the recent pass, Madagascar does not have any real preparedness plans in case of an erupting volcano.  Madagascar does have two active volcanoes off its coast.  Both of them are shield volcanoes.  Shield volcanoes are wider than they are taller and produce the most lava flow due to low viscosity. The eruptions are usually not that explosive and are most common in hot spots. The Volcano Piton De La Fournaise on Reunion Island is 300 miles east of Madagascar and is one of the most active volcanoes in the world.  There have been more than 150 recorded eruptions since the 17th century with the most recent eruption on August 1^st of this year. The volcano Karthala on The Comoros islands is around 200 miles northwest of Madagascar and has erupted more than 20 times since the 19^th century with the last eruption on May 29, 2006. Most of the eruptions have been mild but phreatic explosions have occurred in 1918, 1948, 1991 and 2005.  Phreatic explosions occur when magma heats surface water so quickly that it turns to steam causing an explosion of steam, rock, water and Ash.  In 2005, 30,000 residents were evacuated after an eruption because there was a risk of lava flow and deadly volcanic gas.  They returned to their homes and found ash tainted water.  These volcanoes don’t appear to pose much of a threat to Madagascar.  If one of them had a huge eruption causing part of it to fall into the ocean, it could potentially cause a tsunami.  If Karthala had a huge phreatic explosion, ash could potentially reach Madagascar which might pollute the water, damage crops, and cause respiratory problems for animals and humans. 

 REFERENCES

 

Kellor, Edward A., Devecchio, Duane E., (2015) Natural Hazards, Earth's processes as Hazards, Disasters, and Catastrophes (4TH ED).

 

Piton De La Fournaise, www.Wikipedia.org

Mount Karthala, www.Wikpedia.org

Karthola Volcano, Comoros – John Seach, www.volcanolive.com/Karthola.html

Phreatic eruption, www.Wikpedia .org 

 

MADAGASCAR AND TSUNAMIS

     Tsunamis are ocean waves caused by a displacement of ocean water which can be caused by an earthquake on the ocean floor, an underwater land slide that may be triggered by an earthquake, the collapse of part of a volcano that falls into the ocean or a comet or asteroid striking the ocean.  In 2004, an earthquake with a magnitude of 9.1 occurred off the coast of Sumatra, Indonesia.  It was one of the worst natural disasters in recorded history with a death toll of over 230,000. Most of the deaths were caused by the tsunami which followed after the earthquake.  The tsunami affected many countries around the Indian Ocean causing death and damage as far away as Africa.  In Madagascar, waves of up to 33 feet were seen in the southeastern side of the island.  This resulted in one death and left over 1000 homeless.  Most victims around the Indian Ocean were not aware of the tsunami even though it took hours before the waves to arrive because there was no warning systems.  Because of this, The Indian Ocean Tsunami Warning System was constructed and became operational in 2006.

     Sumatra is 5581 miles away from Madagascar.  The Arabian, Indian, Antarctic and Indo- Australian Plate boundaries which surround Madagascar are much closer.  If  an earthquake occurred on one of these plate boundaries close or of a similar magnitude that hit off the northern coast of Sumatra in 2014, the death and destruction in Madagascar would be much greater then what was experienced in 2004.  Madagascar has two active volcanoes off its coast on each side of the island. The volcano Piton De La Fournaise on Reunion Island just erupted on august 1^st of this year and is around 300 miles east of Madagascar.  On the northwest side of Madagascar are the Comoros Islands where the volcano Karthola is located.  About 200 miles distance from Madagascar, it erupted on May 29, 2006.  A volcano that erupts can produce a tsunami if enough of it falls into the ocean and produces substantial waves.  The Davie ridge is an underwater ridge located between southeast Africa and Madagascar.  In May and June of 1985, a sequence of earthquakes occurred with up to a magnitude of 6.4 in the northern part of the ridge.  This did not produce a tsunami but could have if the magnitude was bigger. I could not find any information about a tsunami, other than the one in 2004, striking Madagascar in recent history. The risk of a tsunami may be slight but it could potentially happen if one of the scenarios above took place.   

     Even with The Indian Ocean Tsunami Warning System in place, I don’t know how well the government of Madagascar would be able to disperse this information to a large portion of its population quick enough to save lives.  Madagascar has a poor telecommunication system.  In cities some people own phones and have internet access but not in many rural areas. Only 15% of the population have access to electricity. Most people don’t own phones, televisions or radios because of this and because of extreme poverty could not afford these devices anyway.  In cities there at least would be some people who have access to television and radio but 70% of the population live in rural areas.  By the time many people would get this information, it would be too late.  Also, since most people don’t own a car, most would have to walk inland or go to higher ground so being able to get this information in a timely manner would also be important.    

 REFERENCES

Kellor, Edward A., Devecchio, Duane E., (2015) Natural Hazards, Earth's processes as Hazards, Disasters, and Catastrophes (4TH ED).

Piton De La Fournaise, www.Wikipedia.org

Mount Karthala, www.Wikpedia.org

Madagascar - Wikipedia, the Free Encyclopedia, www.wikipedia.org

2004 Indian Ocean earthquake and tsunami, www.wikipedia.org

Earthquakes in the Davie Ridge-Madagascar region and the…adsabs.harvard.edu/abs/1988jgr…9310439g

Access to electricity (% of population) /data/table. data.worldbank.org

Impact of 2004 in the island of the Indian Oceans...www.hindawi.com/journals/emi/2011/920813

MADAGASCAR - EARTHQUAKE PREPAREDNESS

     Madagascar does experience earthquakes occasionally but none have resulted in the loss of life or much property damage.  The Ankaratra Plateau in the center of the island is the most seismically active area.  In 1985 the area experienced a 5.2 magnitude earthquakes and in 1991 a 5.5 magnitude earthquake. More recently on July 11, 2015, a 5.6 earthquake occurred near Vakinankaratra, which is in central Madagascar. To the north of Ankaratra Plateau is the Aloatra-Ankay rift which is also seismically active.  On Jan. 26, 2013, the town of Tulear in the southwest of Madagascar experienced a 5.3 magnitude earthquake which broke some windows but no loss of life or other property damage was reported.
     I could not find any information in regards to Madagascar making any efforts to prepare for an earthquake catastrophe.  Through my research I have drawn my own conclusions about how prepared Madagascar would be if a major earthquake occurs and the scenario is grim.  Madagascar, even by third world standards, is a very poor country.  Around  90% of the population lives on less than $2 a day.  The vast majority of the population does not have extra food or water stored up or even a handy first aid kit to rely on if a major earthquake hits.  These people are barely surviving daily and would be at the mercy of their government or foreign aid for help.  The government of Madagascar has experienced political problems in the last several years.  An illegal coup in 2009 resulted in a suspension of all foreign aid.  Since foreign aid makes up 70% of the national budget, this was devastating to an already struggling government.  In 2014, elections were held and a new leader was elected which resulted in foreign aid being restored.  Still, the GDP (growth domestic product), had a negative growth last year and Madagascar is in debt 3 billion dollars to the United States.  Madagascar does have a government agency to deal with disasters , The National Bureau of Risk and Disaster Management (BNGRC), which by all accounts is very poorly funded and ill-equipped.  The major disasters in Madagascar that result in loss of life and property damage are caused by typhoons and flooding.  Since earthquakes have not been a problem in the past or currently, the focus of the BNGRC I assume would be directed largely at typhoons and flooding preparation and the aftermath.


     The infrastructure of Madagascar is very poor and in many places not even present.  The population is approximately 22 million with 70% living in rural areas.  Only 17% of roads are paved.  The major cities have paved roads and there are some paved roads between major cities but the vast majority of roads are dirt or gravel.  If a major earthquake occurred, it would take much longer to get help to many areas because of the conditions of these roads.  During the rainy season that occurs between November and April, many of these roads cannot even be used because of muddy conditions and flooding.  Although there are medical centers and hospitals around the island, the majority are concentrated in urban areas.  Madagascar has an average of three hospital beds per 10,000 people and an extremely low percentage of trained medical professionals.  In 2010 the healthcare budget was cut by 30%.  If a major earthquake occurred, Madagascar would not be able to provide medical care for many of the injured because of its already compromised health care system.  Clean water and sanitation are current problems that Madagascar faces.  Around 11 million people in Madagascar don't have access to clean water and only 20% have direct access to a toilet.  This has resulted in many people contracting waterborne diseases like bacterial and protozoal diarrhea, hepatitis A and typhoid fever.  An earthquake would only exacerbate these problems, especially in urban areas where the population is denser.  How would a health care system already overwhelmed by injuries caused by a major earthquake be able to care for people developing various diseases like cholera?


     In 1960, Madagascar gained its independence from France.  The vast majority of government buildings in the capital and regional urban centers were built during colonial times.  I doubt that any of these government buildings, or even hospitals and schools, have been retrofitted for earthquakes since Madagascar does not have a history of major earthquakes and the cost would just be too much.  If a major earthquake occurred, many of these buildings would be vulnerable to damage or be completely destroyed.  This would compromise the government's ability to function which would especially be needed during a time of crisis.  In many of the rural area, homes are built with mud, bricks or bamboo-like material.  If a major earthquake occurred, most of these structures would be destroyed leaving much of the population without shelter.  Even for the very small percentage of wealthier individuals who can afford to build their homes with corrugated metal or cement,  major damage if not complete destruction is very likely during a major earthquake.  Deforestation is a big problem in Madagascar not only threatening wildlife but also creating potential hazards.  Many hillsides are especially vulnerable to landslides, especially when there is a lot of shaking going on during an earthquake.  I could go on and on but I think I will stop here.  The one positive note is that Madagascar does not have a history of major earthquakes and hopefully it will stay that way.


REFERENCES


Madagascar - Wikipedia, the Free Encyclopedia, www.wikipedia.org
Madagascar Plates - Wikipedia, the Free Encyclopedia, www.wikipedia.org
Poverty in Madagascar - the Borgen Project, www.borgenproject.org
Madagascar - the Untold Crisis, www.unric.org
Water Aid Madagascar, www.wateraid.org
BNGRC, www.bngrc.org






 

MADAGASCAR AND TECTONIC PLATES

Madagascar is an island country located off the coast of southeast Africa in the Indian Ocean.  Madagascar is also located in the southwest area of the African Plate.  The Antarctic Plate is south of Madagascar and the Australian Plate is to the east.  The Indian and Arabian Plates are located in the north.  All of these plates have boundaries that are divergent.  Divergent boundaries are the result of plates that move away from each other producing new lithosphere which is the outer layer of earth.  This process is called seafloor spreading and occurs at mid-ocean ridges.  The mid-ocean ridges are the result of hot mantle that rises up when the plates move away from each other.  The majority of earthquakes and volcanoes occur along these plates.  Madagascar is around 750 mile from the Antarctic Plate boundary and 1100 from the Australian Plate boundary.  The Arabian and Indian boundaries are even further.  The distance is my own estimation using the map in the textbook and may not be completely accurate but the bottom line is Madagascar is not close to any of these four plates.






Madagascar does not have any active volcanoes presently or in recent times.  There are two active volcanoes close to Madagascar.  To the east of Madagascar is Reunion Island where one of the most active volcanoes in the world, Piton De La Fournaise, just recently erupted on Aug. 25, 2015.  To the north-west of Madagascar are the Comoros Islands where the volcano Karthala erupted April 2005 and in May of 2006.  The Ankaratra Plateau in the center of Madagascar experienced a 5.2 magnitude quake in 1985 and a 5.5 magnitude quake in 1991.  More recently a 5.3 magnitude quake struck Anakao in the south-east part of the island on Jan 13, 2013.






REFERENCES






Kellor, Edward A., Devecchio, Duane E., (2015) Natural Hazards, Earth's processes as Hazards, Disasters, and Catastrophes (4TH ED).






Piton De La Fournaise, en.Wikipedia.org.




Mount Karthala, en.Wikpedia.org




Madagascar - Earthquakes - Earthquakes Today, www.emsc-csem.org/Earthquake.php?id=302161


Madagascar Plates, en.Wikipedia.org