Disaster Trends

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Trends and Patterns of Disasters

Understanding the trends and patterns for tectonic disasters helps to explain the different impacts that take place.

Trends

The frequency of tectonic hazards has remained the same over recent times.
But, the incidence of tectonic disasters and the numbers of people affected has increased.
- So, there is the same number of hazards, but they are affecting more people as disasters now.
Hydro-meteorological hazards (floods, storms, cyclones and droughts) have become more common. This is linked to climate change and high rates of deforestation.

Earthquakes since 1980

There have been between 15 and 40 disasters per year.
Deaths have varied in this time period, with some large events in some years.
Large disasters have skewed numbers of deaths.
- E.g. Banda Aceh (2004) and Haiti (2010).
Economic losses caused by earthquakes have increased.
- This is because there is more to lose as global affluence increases.

Volcanoes since 1980

The number of volcanic disasters has been less than earthquakes.
Death tolls from volcanoes have been much lower than from earthquakes.
- There have only been seven eruptions that have killed more than 100 people.
The wider impacts of some recent eruptions have been significant as large-scale evacuation was needed.

Mega-Disasters

Some disasters can be classed as mega-disasters. These are high magnitude, high impact, infrequent disasters that affect several countries directly or indirectly.

The Himalayas

Some very large tectonic disasters have taken place in the collision zone of the Himalayas. These include:
- Kashmir (2005), Sichuan (2008) and Nepal (2015).
These three events account for 40% of earthquake deaths since 2005.

Other tectonic mega-disasters

Major earthquake events also took place in Banda Aceh (2004) and Haiti (2010) killing over 200,000 people each.
The Tohoku (Japan) earthquake and tsunami in 2011 had worldwide economic impacts.
The Eyjafjallajokull (Iceland) eruption in 2010 also had a global impact both socially and economically. The ash cloud from the eruption disrupted flights all over the world.

Multiple Hazard Zones

Tectonic disasters may form part of wider multi-hazardous zones (where two or more hazards occur) which may involve hydro-meteorological hazards.

Characteristics

Multiple hazard zones are usually:
- Geologically young with unstable mountain zones prone to landslides.
- Tectonically active, which means that earthquakes and volcanic eruptions are common.
- Often on major storm tracks either in the mid-latitudes or on tropical cyclone tracks.
- At risk from global climate perturbations such as ENSO.

ENSO

The El Nino Southern Oscillation (ENSO) is a warm ocean current that replaces the usual cold current off the Pacific coast of South America.
It brings heavier rain than usual on the coast, and drought inland.
It also affects climates further afield such as California and the Philippines.
When other hazards occur in ENSO years, their effects could be multiplied.