Final Blog

Due to Costa Rica's geographical location I believe volcanoes and earthquakes are the most dangerous hazards. Costa Rica is in the Caribbean Tectonic Plate with the Cocos Plate to the West. From the rise the plate is pushed eastward and pushed under the less dense Caribbean plate, the process is called subduction. Since 1900, there have been many moderately sized intermediate-depth earthquakes in this region, including the September 7, 1915 M7.4 El Salvador and the October 5, 1950 M7.8. Under Costa Rica, the tectonic plates Nazca, Cocos and Caribbean all converge just off the Pacific Coast.This makes for a lot of seismic activity. An earthquake of magnitude 6.2 struck central Costa Rica in 2009, resulting in the death of 32 people.

A volcano is a rupture in the crust  that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The same plate tectonics involved in creating Costa Rica’s earthquakes create a line of over 130 volcanoes varying from dormant to exuding lava down the northern half of the country. An eruption at Arenal in 2000 killed two people and chased many out of a Resort located along the volcano. In 1968, the village of Tabacon was destroyed and it was reported seventy-eight people had been killed by an eruption. The lava continued to flow over the next forty years. In 2015, Turrialba volcano released ash and cinders to create a large cloud that closed the international airport. Experts predict that it will continue with higher levels of activity and could impact airport operations as far as 2016.

In order to prevent deaths from earthquakes, I would order a reconstruction of homes made from adobe to Masonry buildings because adobe buildings are the riskiest types to build. I would set up community buildings with the purpose of housing individuals while their home is rebuilt. I would provide community training in all towns with basic earthquake training and care packages with water, first aid kits and canned food as well as radios. In the event there was a major earthquake I would have extra trained firemen or paramedics aside from the ones already hired. I would also fund community groups dedicated to checking in on the community and reporting any damage or injuries. In attempt to minimize the volcanic destruction I would immediately send out a warning signal of high alert for volcanic activity since earthquakes can be triggered by strong earthquakes. Volcanic researchers would be in charge of determining if evacuation on towns near volcanoes is necessary or recommended. In turn, shelters as well as assistance would be provided to help evacuate. I would also have emergency crews all around. 

I would target help to the places most at risk and then focus additional help to any other possible at risk towns. In Costa Rica the riskiest areas all towns and resorts near volcanoes. There is a variety of them so it's hard to choose one specifically. Any central valley town also doubles its risk since the forests and mountain ranges make it difficult to travel through. I would prefer to build a home on the Caribbean coast because it is more common for earthquakes to happen on the Central Pacific Coast due to the Ring of Fire, faults lines in the Earth’s crust around the Pacific Ocean, which is a hotspot for earthquake activity. 

Given the geological and geographic variety, this ecosystem is greatly affected by a variety of natural events, not all of them good. It is important to be aware of what could happen and understand how to keep oneself safe. Being in charge of my country I would express the importance of being educated on the consequences an earthquake and volcanoes could bring. In order to save lives and reduce injury I would put into place unlimited funding and resources to the science that would help up determine any signs of possible hazard threats.

Sources:

• https://www.fema.gov/earthquake-safety-home
• Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20
• https://internationalliving.com/best-places-to-live-in-costa-rica-five-top-expat-havens/
• https://costa-rica-guide.com/travel/health-safety/natural-disasters/
• https://www.express.co.uk/news/world/878823/costa-rica-earthquake-san-jose-parrita-usgs-ring-of-fire-pacific-ocean-magnitude

Coastal Hazards in Costa Rica

The coastal environment is one of rapid change. Costal morphology is influenced by plate tectonics. The most serious coastal hazards include strong coastal currents, coastal erosion of beaches, hurricane storm surges, cyclones, and tsunamis. Waves that arrive at coastlines are generated by offshore winds and the size of the wave is related to the speed of the wave, duration of the wind blown by a storm, and the wind distance across the water surface. Wave period remain constant but velocity decreases and height increases. Sea levels are influenced by tectonic movements of the land, water and climatic factors.  Coastal erosion is a serious natural hazard. Erosion at a particular beach can be determined if input of sand exceeds output then the beach will grow, however, if output exceeds input then erosion occurs. Humans try to control coastal erosion by building structures that are designed to minimize erosion but end up causing damage and more erosion to beaches.

In Cieneguuta, Costa Rica on March 28th 2017, a government initiative that allowed the construction of a paved coastal street with a bicycle lane, playground, and sports space.  However, the 2.5 million-dollar investment is threatened by coastal erosion and the rise in the level of water in the sea that occasionally floods the new street. "The most conservative estimates put the sea level rise between 20 and 60 centimetres by 2100, but new studies point to a still higher increase, which would irremediably damage the life of the whole town, whose inhabitants make a living fishing or working on the docks of Puerto Limón" according to Diego Ortiz. Community leaders and local residents grow a fear of the waves eroding the foundations of the road and bicycle lane and end up destroying the new streeet. The waves reach the doors of the houses at high tide and residents use sandbags in order to guard their houses. The rest of Costa Rica’s Caribbean coastline has similar problems with erosion, said oceanographer Omar Lizano, of the University of Costa Rica’s Centre for Research in Marine Sciences and Limnology (CIMAR). Lizano has been monitoring the beaches on the Caribbean and observing how the waves have gained metres and metres of sand for many years. A study published in 2014 by the Climate Change and Basins Programme of the Center for Tropical Agricultural Research and Education (CATIE) determined that "the sea rises on average two millimetres per year along the coast of the eastern province of Limón, which covers the country’s entire Caribbean coast, and whose capital is Puerto Limón." The people of Cienaguita are asking for more resources to design new protective structures. Costa Rica is in the initial stages of its National Adaptation Plan, a broad document that will define the path that the country will take to protect itself from the worst impacts of climate change, and urban settlements and coastal areas shall be priorities. Unfortunately the government claims to have no funds but does have resources dedicated to monitoring sea levels and reporting their findings. 


Sources:

• http://www.cimar.ucr.ac.cr
• https://www.catie.ac.cr/en/
• http://www.ipsnews.net/2017/03/costa-rican-town-fears-that-the-sea-will-steal-its-shiny-new-face/
• Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20

Extreme Weather in Costa Rica

Hurricane season in Costa Rica lasts from June to November. The danger of hurricane season comes from heavy rains that accompany the severe weather pattern. This could result in landslides, mudslides, flooding and disruptions to essential services. Landslides and flooding occur mostly in the Atlantic section of the country. Costa Rica has two seasons, rainy and dry. The rainy season occurs from May to November and the dry season from December to April. The excess rain in extremely humid areas or even in dry areas where the soil can't handle the amount of water may cause floods that can devastate crops, destroy houses and even result in deaths. In November of 2010 heavy rains caused landslides that killed 27 people and injured many others. Many roads were flooded or blocked by landslides.

Sources

https://www.costaricantimes.com/risk-for-extreme-weather-in-costa-rica/33732

https://www.twoweeksincostarica.com/weather-costa-rica/

Costa Rica Mass Wasting Hazards

Mass wasting is a comprehensive term for any type of downslope movement of earth materials (Keller 216). The most common landforms are slopes they are evolving systems where surface material if often moving downslope this process is call mass wasting. Landslides are often complex combinations of sliding and flowage. The forces that produce landslides are determined by the type of material on the slope, topography, and slope angle, climate, vegetation, water and time (Keller 218). 

The danger of hurricane season lies with the heavy rains that accompany this severe weather pattern which could result in landslides, mudslides, flooding and disruptions to essential services. Landslides and flooding occur mostly in the Atlantic section of the country. In November 2010 heavy rain caused deadly landslides that killed more than a dozen people and injured several others. Many roads were flooded or blocked by landslides.

There has been implementation of mapping out the risky areas in Costa Rica. The Costa Rica Red Cross initiated a community training programme in disaster preparedness and prevention, community first aid and psychological support. The idea of the early warning system was put to the community on the understanding that the community itself would operate and follow through with this system. Establishing identification, prevention and correction procedures can help minimize the landslide hazards (Keller 236). Careful engineering practices can minimize the danger of natural slides. By identification grading codes have been put into place in order to reduce landslide damage. A drainage program lowers water pressure in slopes. It is expected that although preventions and procedures have been put into place, landslides are said to increase throughout this century (Keller 239). 

Sources:

• http://www.welovecostarica.com/costa-rica-landslides-watch-out/
• https://www.preparecenter.org/resources/landslide-early-warning-costa-rica
• Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20

Volcanic Hazards in Costa Rica

Volcanic activity is related to plate tectonics. Most volcanoes are located near active plate boundaries (Keller 128). About two thirds of Earth's active volcanoes are above sea level located within the "Ring of Fire". Features of volcanoes are vents, craters, and calderas. Eruptive behavior of specific volcano types can be predicted (Keller 133). The Volcanic Explosion Index, VEI, is a relative scale where the different eruptions can be compared "based on quantitive and qualitative observations of explosivity" (Keller 134). There are different kinds of volcanoes such as:

The stratovolcanoes are cone shaped and occur above subduction zones. These volcanoes are characterized by explosive eruptions (Keller 134).

Lava Domes are smaller than stratovolcanoes. These domes can be explosive and nonexplosive.

Shield volcanoes are the largest. They are common in mid ocean ridges and over mid plate hot spots (Keller 137). They are usually nonexplosive lava flows.

The continental caldera volcanoes are created by violent eruptions. They often present a volcanic hazard for the next million years.

Effects of volcanic activity include lava flows, pyroclastic hazards, emissions of poisoned gases. Loss of land and property can result from lava flow. Pyroclastic hazards involve ash falls and in turn ruin agriculture land. Secondary effects include debris flows and mudflows. Volcanoes are also linked to fires, earthquakes, landslides and climate change (Keller). However, volcanoes provide fertile soils, mineral resources and new land.
Today we minimize the danger of volcanic activity by forecasting and Volcanic Alert Codes. Costa Rica is home to several volcanoes and is apart of the "Ring of Fire". Poas remains one of Costa Rica's largest and most active volcanoes. Although the last major eruption was in 1910, the volcano remains steadily active to this day, and visitors can still see geysers exploding into the air, some reaching as high up to 820 ft (Arenal.net). Costa Rica's tallest volcano is Irazu and is located in the highlands. Costa Rica's volcanic activity has taken them to sending out alerts in case of any threats. They use cell phone alerts as well as broadcasting them through television as well as non profit groups to help the elderly in case of evacuations. They have scientists dedicated to follow the activity of volcanoes in Costa Rica such as the Volcanological and Seismological Observatory of Costa Rica (OVSICORI) and the National Seismological Network (RSN).

Sources:

• https://www.arenal.net/volcanoes-costa-rica
• as-turrialba-volcano-erupts-again-scientists-warn-of-increased-health-risks-economic-damage
• Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20

Earthquakes

The constant movement of Earth's tectonic plates have reshaped continents and oceans over the past billion years. If the movement beTtween adjacent plates was smooth and continuous we would be unaware of the movement between the plates. Unfortunately, that is not the case. Plates move "episodically"(Keller 53) every few hundred years. "These large episodic movements of the plates cause the violent ground shaking we know as an earthquake" (Keller 53).  There are three key factors that determine the shaking you feel during an earthquake: 

1. Earthquake magnitude
2. Location in relation to epicenter and direction of rupture
3. local soil and rock conditions

Large earthquakes release enormous amount of energy. Seismologists measure this energy on a magnitude (M) scale. "Earthquakes are given description adjectives based on their magnitude scale" (Keller 61). Most earthquakes are described as major(M 7-7.9) or strong (M 6-6.9) (Keller 61). Earthquakes classified as major can cause "widespread and serious damage" (Keller 61). Whereas, strong earthquakes can cause "considerable damage" (Keller 61). The most powerful earthquake is called a grand (M 8+). The amount of ground motion produced by an earthquake is related to its magnitude, depth and environment where it happens. Buildings more prone to damage are the ones that are constructed on unconsolidated sediment, artificially filled land, water saturated sediment. All are said to amplify the shaking (Keller 63). Also, the buildings that are not designed to withstand significant horizontal acceleration of the ground or have natural vibration frequencies that match the frequencies of the seismic waves are highly subject to damage. 

Earthquake intensity varies with the severity shaking and is affected by proximity to the epicenter, the local geological environment and the engineering of structures (Keller 64). Earthquake intensity is shown in maps and recently the U.S. Geological Survey, USGS opened an online survey, "Did You Feel It?" to solicit reports from people in the US who recently felt an earthquake.

According to the USGS website, along the western coast of Central America, the Cocos plate subduct towards the east beneath the Caribbean plate at the Middle America Trench. Convergence rates vary between 72-81 mm/yr, decreasing towards the north. This subduction results in relatively high rates of seismicity and a chain of numerous active volcanoes; intermediate-focus earthquakes occur within the subducted Cocos plate to depths of nearly 300 km. 

Since 1900, there have been many moderately sized intermediate-depth earthquakes in this region, including the September 7, 1915 M7.4 El Salvador and the October 5, 1950 M7.8 Costa Rica events. The boundary between the Cocos and Nazca plates is characterized by a series of north-south trending transform faults and east-west trending spreading centers. Under Costa Rica, the tectonic plates Nazca, Cocos and Caribbean all converge just off the Pacific Coast.This makes for a lot of seismic activity. In the area where the September 5 quake hit on the Nicoya Peninsula, the Cocos plate was diving beneath the Caribbean plate. Currently, Costa Rica has changed to Masonry buildings rather than adobe ones because adobe buildings were the riskiest  types to build (gfdrr.org). There have been many groups arranging plans snd helping individuals tear their adobe buildings to modern masonry buildings. 

Sources

• https://gemrisk.wordpress.com/2016/03/04/profiling-earthquake-risk-in-costa-rica/
• https://earthquake.usgs.gov/earthquakes/eventpage/us2000bmhe#region-info
• gfdrr.org
• Benz, Harley. “USGS Open-File Report 2010-1083-A: Seismicity of the Earth 1900–2010 Caribbean Plate and Vicinity.” USGS Publications Warehouse, pubs.usgs.gov/of/2010/1083/a/.
• Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20

Tectonic Plate?

Earth's lithosphere is broken into tectonic plates that move relative to one another. Tectonic processes are driven by forces within Earth (Keller 33).  Plate tectonics are often the cause of natural hazards such as volcanoes and earthquakes. All major plates include an ocean basin and a part of the continent. Plates can be small or large There are three types of plate boundaries: divergent, convergent and transform.

1. Divergent: Divergent boundaries occur when neighboring parts of plates are moving away from each other and new lithosphere is being produced (Keller 36). 
   
2. Convergent: Convergent boundaries occur when plates move towards each other (Keller 36). 
   
3. Transform: Transform boundaries occur when the edges of two plates slide past each other like the San Andreas fault in California (Keller 38). 
   

Everything living on Earth is affected by plate tectonics. The types of and properties of the rocks which we depend for land, our mineral and rock resources, and soils in which our food is grown  is determined by the tectonic processes occurring in the plate boundaries (Keller 48).

Costa Rica is in the Caribbean Tectonic Plate with the Cocos Plate to the West. The Cocos plate moves Northeast relative to the Caribbean plate. Frequent earthquakes and volcanic activity happen in Costa Rica due to the competitive movement between the two plates.

Source: 

Keller, Edward A., et al. Natural Hazards, Earth's Processes as Hazards, Disasters, and Catastrophes. Fourth Edition. 20