2

Natural disasters are extreme geophysical events,

biological processes and widespread

technological accidents

Danger may affect:

People Properties Environment

3

Major natural disasters and anthropogenic accidents are:

Car accidents

Accidents with chemical

compounds

Hunger

Cyclones, hurricanes,

typhoons, storms

Tsunami

Epidemics

Insect invasions

Extreme cold or heat

periods

Avalanches and landslides

Displacement or

movement of people

Flooding

Public unrest

Drought

Fires

Volcanic eruptions

Earthquakes

4

According to the probability of death cases

Damage by natural disasters (1980 - 2008)

Number of

disasters Number of

dead Number of

victims Economic losses,

billions EUR

Drought 410 558 565 1 551 455 112 54, 745

Storms 1 211 402 911 496 639 560 379,460

Earthquakes 706 385 630 136 333 515 249, 771

Tsunami 18 229 551 2 481 879 7,441

Floods 2 887 195 843 2 809 481 489 282,779

Epidemics 1 039 183 278 19 411 394 ?

Heat waves 126 89 889 4 614 411 22,261

Vulcano eruptions 140 25 197 4 080 791 2,042

Landslides 366 20 008 7 031 523 0,004

Tornado 182 4 780 12 710 204 22, 417

Avalanches 73 3 532 69 637 0,626

Fires 294 1 666 5 766 092 30, 453

Invasions of insects 75 0 2 200 0,164

6

Natural disasters, the annual average economic loss due

to natural disasters, 1980-2008

7

In subsequent decades, the increase of the global

temperature will cause significant climate changes that

will be bigger and stronger than ever

in the past 10 000 years

The hardest will suffer those countries which existence is highly

dependent on intensive use of natural resources

8

World population in 2011 exceeded 7 billion people,

mainly due to the population growth in developing countries

Urbanization - migration of population from rural to

urban areas, caused by depletion of agricultural conditions

and due to global economic forces, resulted with excessive

growth of urban population

9

Media aware

Dead

Injuries

Homeless

Disrupted

Tax payers

Inconvenienced

Aid donors

Region

Place of disaster

Country

World

Impact of natural disasters affect a wide range of persons

not only direct victims in the disaster area

10

Environmental risk studies become more

complex, but also narrower and more detailed in some subsectors

Natural scientists are focused

more on the natural

processes, the nature of

developments in the mechanism and frequency

Social sciences are looking for

answers exploring public

reaction and behaviours in

critical circumstances

But decision-makers need real

recommendations for solving a

problem rather than just a theoretical

discussion

?

11

Even if a considerable damage is caused to property or the

environment, direct danger to people lives is

perceived as the most dangerous effect

People's vulnerability and sensitivity is often caused by a lack of emergency management

12

Natural and anthropogenic accidents may be

classified by the inducing factors:

Atmospheric factors

Hydrologic factors

Geological factors

Biological factors

Technological factors

Social violence

Complicated danger factors

13

Tangible effects are those for which it is possible to estimate

losses in monetary terms, such as the damaged property to

restore the necessary resources

Undetectable effects – actual effects, but impossible to

determine in monetary expression:

loss of life can be detectable medically and legally, but

economical or financial loss value calculation is very complex

Direct effects are effects

that appear immediately after the disaster

Indirect effects appear later and

sometimes can be difficult to identify and link up with a disaster

Natural disasters can cause direct

and indirect effects:

14

Natural disasters recurrence time is the average

time between two following natural disasters

Most natural hazards can be measured by some physical

parameters within a specific scale

15

The most dangerous places are around the tectonic fractures - usually in high mountains or on coastal areas

About the half of the world's population is living in 60 km

coastal area near the river deltas or at the seaside

About 25% of the world population are exposed to

natural disasters, the majority of them live in

developing countries

16

Sensitivity is a critical factor, that can be

increased by people poverty, age, health and human physical abilities

Well equipped societies and families with access to

resources can more easily survive if natural disasters occur

Access to the information and social communication

networks also is very important

17

Earthquakes and volcanic eruptions occur

mainly around the borders of the

lithosphere plates

Lithosphere plates are from 6 km to 200 km thick, solid Earth's outer shell that consists of different sized boards, which are:

in some places moving away from each other – divergence

moving towards one another – convergence

slipping one beneath the other or one moving along the second

Convergence Divergence

18

San Andreas fault in California

20

Earthquake strength can be measured using the Richter

scale: earthquakes, power is expressed in terms of the size

of the output energy, which can be measured by

seismograph amplitude ratio scale

For earthquake intensity determination Mercalli scale is

used, with the scores from I to XII determine the impact the

earthquake has had on people, buildings and the environment

Minor: up to magnitude 4

Little: magnitude 4-5

Harmful: magnitude 5-6

Destructive: magnitude 6-7 balles Strong: magnitude 7-8

Disruptive: more as magnitude 8

21

Earthquakes

primary effects are

associated with the

earth shake, and

vertical or horizontal

ground movements

This leads to a strong

impact on people and

structures

Secondary effects of

earthquakes are

associated with rock

mass movement,

such as rock falls and

landslides

Earthquakes are characterized by primary and secondary effects:

Tsunami

On December 26, 2004 India ocean earthquake (9.1 magnitude) with epicentre at

Sumatra, Indonesia aroused huge tsunami wave, which killed approximately 230 000

persons in 11 countries, mainly in Indonesia, Sri Lanka, India and Thailand.

Tsunami, India ocean, 26.12.2004.

24

25

Flooding is irregular water level rise at any time and

place, which occurs in floodplain and other areas

Due to the origin of nature there can be separated

floods and flooding:

Flood is a river water treatment

phase characterized by the seasonal

largest watering that occurs yearly

or seasonally, and usually at the floodplain areas

Flooding can be characterized by

intermittent (at any time and place)

and a sharp but temporary rise of

water level, which occurs during floodplain or other areas

Flooding or flood is usually associated with rivers, and

less with lakes or other water bodies

North Sea

October 11. - 12.,

1634.

27

Flood risk can also

be a result of

human economic activities

Extreme flood situations is often

associated with heavy rain, which

causes storms, or rapid melting of snow

In some cases flooding occur

when natural or man-made dams are broken

Earthquakes in the

ocean can cause catastrophic

floods, by releasing of massive tsunami waves

Threat of flooding:

Flooding in urban areas present more difficulties

because of natural ground surface is built with a water-

tight materials

28

Flooding primary physical effects

Secondary effects result in decrease of water quality

Flooding effects can be primary and

secondary:

However, flooding may also give beneficial effects on river

ecosystems – by groundwater recharge and increase of soil fertility by bringing fertile mud into soils

29

In Europe flooding occurs

mostly in central and

southern part and is caused

mostly by rainfalls and may

affects about 1.5% of the

population

However, 70% of the world

flooding occurs in Asia

Floods in Bangladesh

31

In flooding risk areas risk assessment is very important

therefore the flooding frequency should be detected over

a specified period

Flooding hazard mitigation can be implemented in various ways:

improvement, creating of

channels, straightening of river beds etc.

creating of wetlands, which

work as water sponges during flooding

flooding prevention barriers

helps to keep and store a certain

volume of flooding waters to

dissipate later steadily

building of permanent or

temporary embankments

along the river banks certain in places

32

Territory of Latvia is divided into four river basin

management areas - Venta, Lielupe, Daugava and Gauja

33

Daugava River flood is seasonal, mainly formed in the spring, when

snow melts, rivers are rising water levels and ice jams.

Strong wind affects the water flow from the Gulf of Riga - water can be

blown into the Daugava River, raising the water level and threatening the city of Riga.

34

Biological factors or agents, which can lead to disasters:

Different nature of the diseases

and epidemics or pandemics

Undesirable, harmful or noxious

plant and animal invasions

Insect invasion with its

consequences on people,

environment and agriculture

Predatory animal attacks

Fish, crustaceans and molluscs

pollution

Forest fires

Bacteria Viruses Fungi Protozoan

Algae Plants Insects Animals

Biological agents can cause:

35

Epidemic expands

when in the

population appears

more and more new

cases of certain

disease in a short period of time

If an epidemic is covering

very large areas, it is called a pandemic

Simple diseases

that are a little

variable but rather

in a small scale,

can be called as endemic

Infectious diseases are characterized by several specific terms:

Nowadays, the world is

concerned about the wide

spread of such diseases as

malaria, tuberculosis,

influenza strains

Malaria

36

Anopheles albimanus mosquito

feeding on a human arm

An estimated 655,000 people died from malaria in

2010, a decrease from the 781,000 who died in 2009,

according to the World Health organisation’s 2011

World Malaria Report, accounting for 2.23% of

deaths worldwide.

However, a 2012 meta-study from the University of

Washington and University of Queensland

estimates that malaria deaths are significantly

higher - the study estimates that 1,238,000 people

died from malaria in 2010.

37

Fire is the uncontrolled spread of fire which may

occur in populated areas or in natural areas

Characteristic parameters of fires are:

Distribution speed

Quantity of material burning

Topography

Geographic location

Cause of the outbreak

Weather conditions

38

Adapting occur after fires

including the appearance of

plant physical protection from

heat and increased growth

after the fires

Fires cause considerable

damage to people as well

as for property and material assets

Fires can be characterized by both, negative and positive effects:

Fires sometimes give the benefits,

especially for some species in areas

where the conditions for growth and

proliferation can only occur due to fires

39

Natural causes of fires are:

Large fires can affect both, climate and weather, they

create a regional and even global pollution, fires also

release greenhouse gas emissions

However, many fires occur from human inattention

(dropped cigarette, spark from engine) or from

deliberate abuse

Lightning

Volcanic eruptions

Sparks rock spark

Spontaneous ignition

Smoldering of underground coal or peat layers

40

An important element is the rapid forest fire detection

that can be realized by observation, as follows:

Satellite and aeral monitoring allows to

obtain information, as well as provide insight

into the events of a very broad and even low-risk areas

Forest observations from towers

equipped with surveillance equipment and communication systems

Observations from space

41

Heat periods are long periods of hot weather which expression is dependent on site-specific climatic conditions

Strong heat periods which are very

rare and can lead to:

Power supply disruption

from the increased air conditioning use

Catastrophic

damage to

agricultural crops

Death of thousands

of people from

hyperthermia or overheating

42

In summer of 2003, over the western Europe was spread a

stable anticyclone and temperature contributed to the increase of 20-30% above average

43

Drought can cause the following effects:

Massive people migration

Famine, poverty and diseases

Decline in electricity production,

Drastically reduce crop yields

and livestock survival

Sand and dust storms, causing

desertification, soil erosion

Damage to both terrestrial and

aquatic ecosystems and species

Social unrest and even lead to

war for natural resources, food

and water

44

1973

2001

1997 1987

Lake Chad in Africa from 1965 has been reduced

for 95%

45

Storms occur when rapidly rising or falling atmospheric

pressure areas are crossed by large cyclone or tornado, as

well during a local or frontal a lightning storms

Storm is a very strong wind for which the cumulative

speed over 10 minutes is at least 24 m/s and gusts can

reach up to 100 m/s (360 km/h)

46

Tornado is a devastating and rapidly tapered atmospheric

vortex with the rain and the storm, which usually occurs

when a cool, dry air mass meet the warm, moist air mass,

forcing the warm air to rise to the top suddenly

Hurricane reminds huge gyratory plate

with a diameter can reach up to 500 km,

but in rare cases up to 1000 km

Hurricanes never ! occur over land, just over the

sea or ocean in tropical zone, where

temperatures in the upper layers is at least +27 °C

* Character Wind speed; km/h * Character Wind speed; km/h

Tropical

depression 0–62 3. category 178–209

Tropiskā vētra 63–117 4. category 210–249

1. category 119–153 5. category ≥250

2. category 154–177 Havn’t

information Saffir–Simpson hurricane scale

Hurricane “Katrina” in 2005, USA

48

During the storms, strong air mass collisions cause raindrops

and hail grain collisions in the clouds, creating an electrical

charge, resulting in huge fires spark – lightning

From the enormous heat that is

released as a result of lightning,

nearby air rapidly expands

causing thunder

Most typical type of lightning - lines

that spark discharges in the branches,

whose length is usually 2-3 km