Geophysical systems D1.2

Distribution of hazards

Distribution of hazards

What is used to measure earthquakes

Used to use Richter scale

Now they use the moment magnitude scale

• Moment magnitude - current + more accurate measurement 

  Interpret and record a broader segment of seismic systems 

How are recurrence intervals of earthquakes useful for risk management?

1. Recurrence interval = the average time interval that occurs between two recorded events of seismic activity, of equal magnitude, along the same fault.

   2. San Andreas fault = transform boundary |(no volcanoes formed) - two plates moving at different speeds - build up of pressure -- earthquake 

   3. Parkfield section (straight section of the San Andreas fault)  = magnitude 6 

   4. Many fault lines in california 

   5. Recurrence interval = every 20 years 

   6. Scientists use computer simulations to work out if there's going to be an earthquake 

   7. How wide scale, how many people affected, what areas affected, is there any construction that should not be allowed in an area like this - high risk of damage, eg. airport on this land.

   8. San andreas = big threat to san francisco = less to los angeles 

   9. Lower section on fault = recurrence interval is less - 190 years 

How to prepare for an earthquake - Short and long term

Short term - What individuals can do 

1. Schools - special session on what to do if earthquake

   1. In japan - earthquake prepare drill 

2. Families - first aid kits, water and food, radio 

Long term 

1. Reinforce building codes - accentuated 

2. Power lines - reinforce and redundancies 

3. Avoid building highways that collapse - redesign the roads 

4. Hazard zoning

What is used to measure magnitude of volcanoes

• VEI = Volcanic explosivity index - 0 to 8 scale 

• Amount of erupted tephra 

• Eruption column height 

• Eruption type

VEI levels and examples

0 = trickle of lava - Hawaiian volcano of Kilauea - not tallest part of island but erupts more actively - shield volcano 

1 - gentle eruption - italy stromboli = erupted for almost - Strombolian volcano 

2 - several mild explosions - indonesia mount sinabung has been erupting since 2013 

3 - catastrophic - lassen peak northern california 

4 - happen every other year - 2010 iceland Eyjafjallajokull - high in air 

5 - things more dramatic - mt vesuvius + mt st helens - blue top + lost altitude + erupt out of side - Volcanion 

6 - colossal eruptions - krakatoa - triggered tsunami - 1883 

7 - every 1000 years - indonesia mt tambora 

8 every 50,000 - yellowstone caldera would reach this level if it were to erupt again - us - national park - so massive that people don't understand it is a volcano - supervolcano - if it erupted = would make big difference - many deaths, people, animals - climate would change. = Plinian 

Disaster risk equation

Hazard risk factors - Haiti port au prince 2010

Risk

Risk: To be susceptible to physical or even emotional attack

Capacity

Capacity: The ability of a communtity to absorb and ultimately recover from a natrual disaster

Resilience

Resilience: The ability of a community to bounce back after  hazardous event 

• Affected by income of country 

• Japan = better than Haiti

Hazard

Hazard: The exposure of people to hazardous event which make present a potential threat to people or their possessions including buildings and structures

Vulnerability

Vulnerability: 

• Characteristics + circumstances of community, asset or system that make it available to the damaging effects of a hazard.

Aspects of vulnerability: 

• Physical 

• Social

• Economic 

• Environmental 

Examples: 

• Poor design and construction of buildings - due to governance 

• Linadequate protection of asset - people who choose to hold money under bed rather than a bank account - hazard will destroy this 

• lack of public information and awareness,

• limited official recognition of risks and preparedness measures, and

• disregard for wise environmental management. 

Vulnerability varies across communities and within communities - also over time 

4 aspects of vulnerability

4 types of vulnerability: 

1. Physical vulnerability 

   1. Aspects 

      1.  population density

      2. Remoteness of a settlement 

      3. Site 

      4. Design and materials used for infrastruatire/housing

   2. Example: 

      1. Wooden homes are less likely to collapse in earthquake - more vulnerable to fire 

2. Social vulnerability 

   1. Aspects 

      1. Inability of people/organisations/societies oto withstand impacts due to: 

      2. Inherent social interactions/instituions/systems of cultural values 

      3. Linked to level of well being 

      4. Levels of literacy and education 

      5. Existence of peace and security + acess to basic human rights

      6. Systems of good fovernance 

      7. Social equity

      8. Positive traditional values

      9. Customs and ideological beliefs 

      10. Overall collective organisational systems 

   2. Example: 

      1. When flooding occurs some citizens - children/elderly/differently-able - unable to protect themselves or evacuate if necessary 

3. Economic vulnerability 

   1. Aspects 

      1. Economic status of individuals/communities/nations 

      2. Poor = more vulnerable to disasters - bc they lack the recoutrse to build sturdy structures and put other enginneering measures in place to protect themselves from being negatively impacted by disasters 

   2. Example: 

      1. Poorer families may live in squatter settlements because they cannot afford to live in safer (more expensive) areas 

4. Environmental vulnerability

   1. Aspects 

      1. Natural resource depletion 

      2. Recourse degradation 

   2. Example: 

      1. Wetlands - Caroni Swamp - are sensitive to increasing salinity from sea water, and pollution from stormwater runoff containing agriculture 

Progression of vulnerability

People who are more vulnerable than others

• Poor 

• Children 

• Disabled 

• Elderly 

• Females - Carer role 

  • For example, according to an Oxfam survey, four times as many women than men were killed in Indonesia, Sri Lanka, and India during the 2004 tsunami because men were taught how to swim and climb trees at young ages, while women were not.

• Urban populations can have better access to healthcare and their needs can be more easily met following a disaster.

Initiative that could be taken to reduce vulnerability ro natural disasters

• Increase level of preparedness - emergency kits - education 

• building prevention in hazard areas

• Improve quality of housing and infrastructure

What geographic factors contribute to geophysical hazards becoming disasters?

- Geographic factors = physical 

• Slope 

• Location - near coast line → create tsunami 

• Liquefaction = secondary hazard of earthquake 

• Rural vs urban location 

  • If epicentre in urban location = affect more people 

• Time of day 

• Degree of isolation

What geographic factors contribute to geophysical hazards becoming disasters? - examples

2004 Indian Ocean tsunami in Banda Aceh, Indonesia 

• Altitude - how close to sea level

• Location/Direction of the wave = affect land 

• Relief plane - how flat or hilly 
  
  
  

2021 Nyiragongo eruption in Dominican republic of congo 

• Gradient of slope - influence where lava flow goes

  • Valleys were affecting flow of lava  

• Where plumes are - living directly above a plume = must higher risk 

• Type of eruption - lava erupted from flank of volcano 

2010 7.0 earthquake in Haiti 

• Tsunami risk 

• Slope 

• Underlying geology that effects shaking ons surface  

• No liquefaction on hillside but near coast 

• Relief 

2018 in Palu earthquake and tsunami Sulawesi

• When tide goes far out it is a sign of the wave - wave = very large 

- Epicentre triggered earthquake which then caused tsunami which channelled into that small area - waves became bigger because less space bc is channelled + triggered liquefaction and landslide

- inlet 

TIming of event

• Most people were asleep - but scientists figured out it is better when they were sleep because if it was during the day thousands of people would have died because of poor infrastructiure 

• A small matter of what time it occurs can make a huge impact on the exposure to risk.

• L'Aquila in italy

Rural vs urban

• In urban places - can get help faster in terms of 

  • emergency aid

  • search and rescue 

  • temporary shelters

• In remote/rural areas it is much more difficult to get in the help fast

Local factors

• Type of eruption 

• Altitude

• Location relative to the direction of tsunami waves 

• Inlet 

• Geology 

• Soil type