Earthquakes Flashcards
What is the Seismic gap theory?
The assumption that all parts of a fault will move eventually, meaning that an area of fault that hasn’t had any seismic activity in a significantly long time will be the next area for large seismic activity to take place.
Haiti Earthquake Stats
-GDP of £15.8 Billion
-GDP per capita of £968
-Capital of Port-Au-Prince
-Life Expectancy around 64 years
-Population in 2010 of 10 million, 3 million in the capital.
-Located on conservative Caribbean-N.American boundary
-Magnitude 7 on Richter scale
-Shallow focus, 13km
Literacy rate of 49% in 2006
Haiti Earthquake impacts
-230,000 deaths
-300,000 injured
-1.5 million displaced
-Widespread cholera outbreak killing 10,000
-2 million without food/water
-50% of buildings in capital destroyed
-Damages of $8 billion, 120% of GDP
-8 hospital destroyed
-Worsened political situation, leading to civil unrest from 2018 onwards
Haiti Earthquake Preparation
-72% of Haiti on <$2/day, limiting access to preparation resources.
-Haiti’s government was already heavily indebted and reliant on international aid, couldn’t really afford to prepare.
-over 90% of buildings in Haiti were non-engineered/informal settlements and so weren’t earthquake resistant.
-Poor education meant there was limited disaster awareness
-Food insecurity meant emergency stockpiles were low/non-existent.
-Last major Hurricane was 1860 so most of available preparation went towards the more frequent flooding.
-Overall, very little preparation.
-Since them, USGS helped implement seismic education programs in schools.
Haiti Earthquake Prediction
-Not Predicted specifically in terms of timing or magnitude, but was identified as being an area of high seismic risk.
-Absence of recent seismic activity indicated as seismic gap
-Due to the poverty in Haiti, it couldn’t afford the necessary infrastructure needed for prediction, such as GPS monitoring stations.
Haiti Earthquake monitoring
-There was a lack of understanding about how different geographical systems worked. Low income levels meant it was impossible to invest in improving this.
-Only one official seismic monitoring station.
-USGS has been supporting Haiti with earthquake awareness since 2010 (cut under trump?)
-In 2013, 15 seismic monitoring stations were opened.
-network of seismometers called the ‘Raspberry shake’ network installed across Haiti. Based on Raspberry Pi’s so very cheap.
Japan Earthquake Stats
-GDP in 2011 of $6.2 trillion
-Magnitude 9.0 occurred on March 11 2011
-Fourth most powerful earthquake ever recorded globally.
-Epicenter 72km east of Oshika Peninsula at a depth of 32km
-located along the Pacific ring of fire where the Pacific plate subducts under the North American and Eurasian plates
-15,000 Fatalities.
-Physical Displacement of crust caused a massive Tsunami
-Tsunami reached heights of up to 40 meters.
-Fukushima power plant damaged, causing severe environmental impacts.
Japan Earthquake Preparation
-Japan suffers ~1/5 of the worlds most powerful earthquakes so people are generally prepared.
-Strict building codes means that many buildings have built in shock absorbers or deep foundations to prevent collapse.
-Early warning systems are in place
-Regular emergency drills are carried out in schools and workplaces.
-Many households have an emergency earthquake kit ready.
-The EEW systems means that bullet rains can stop safely during an earthquake.
-Investment in sea walls incase of tsunamis
-nuclear reactors in affected areas automatically shut off.
Japan Earthquake Preparation evaluation
-The scale of the 2011 earthquake was underestimated so some preperations weren’t effective.
-Sea wall wasn’t tall enough for the 40m Tsunami in some places.
Some of the evacutaion centers overwhelmed.
-In some affected areas, mobile and landline communication cut off which limited responses and negated some effectiveness of preperation.
-65% of fatalities were elderly so the preparation may not have been equally effective for all demographics.
Japan Earthquake Prediction
-There was an inability to predict the earthquake specifically due to the lack of preceding smaller earthquakes and general difficulty in predicting earthquakes.
-Being located along the pacific ring of fire, Japan is prone to seismic activity so people were aware of the possibility of an earthquake.
-Impossible to predict a 9.0 magnitude earthquake.
-the EEW system detected the initial seismic waves and send out a warning within seconds.
Japan Earthquake monitoring
The Japanese meteorological agency (JMA) is in charge of the system compromising 200 seismographs and 600 seismic intensity meters.
-They used InSAR to monitor ground deformation.
-Monitoring is used to target relief and makes responses more effective, reducing the impacts.
-Japan is in a very strong economic position which means that it is able to have such an advanced monitoring system.
