•Pacific Ring of Fire

•75% of Earth’s active and dormant volcanoes

•Volcanism is mostly focused at plate margins OR hot spots

Where are most of Earth’s volcanoes?

•Pacific Ring of Fire stretches along east Asia, across Alaskan Islands, and along the coast of the Americas

•US contains only about 10% of all active volcanoes

Where are most of Earth’s volcanoes?

•There are thought to be about 600 million people living close enough to active volcanoes to be affected when they erupt. •Casualties from volcanic eruptions have been modest (around 300,000 in the last 200 years) compared to other geohazards, but socioeconomic losses and disruption can be considerable.•The modern globalized world is vulnerable to very large volcanic events, making the study of return periods, environmental effects, and consequences a key goal of volcanology.

How do volcanoes affect society?

•Flooding• Due to rise in water level/glacial melting• Destroys structures, obstructs traffic (air

traffic impeded by ash)•Global Climate Impact• Sulfur clouds make Earth’s atmosphere

more reflective, cooling the planet• Interferes with crop production

•Property Damage• ex:• Insurance is not widely available and is

costly• why?

What type of risks do volcanoes pose?

•Around the world, disasters occurs each day. Sometimes the impacts are felt locally, other times, the event reaches across state and national boundaries.

•Globally, the number of natural disasters has increased 4X during the past 3 decades—from about 120/year during the 1980s to roughly 500/year now. These disasters exert a uneven impact on the world’s poorest and most vulnerable individuals.• why?

How do we analyze disaster risk?

•To calculate the risk of a natural disaster occurrence, we have to have information about past occurrences.

• This helps us estimate return periods and better prepare and manage future events.

•Disaster risk can be calculated by dividing the number of past events by the time period over which they occurred.•Example:

How do we analyze disaster risk?