- solid material of varying grain size ranging frovolcanic bombs to ash, all ejected into the atmosphere.

- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- solid material of varying grain size ranging frovolcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

– Molten rock (magma) flowing onto the surface.
- Acid lava solidifies very quickly, but
- basic lava (basaltic) tends to flow some distance before solidifying (for example, on the Hawaiian Islands)

- solid material of varying grain size ranging frovolcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- solid material of varying grain size ranging frovolcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- In 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- example: in 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- when an eruption melts glaciers and ice caps, serious flooding can result.
- example: Iceland in 1996 when the Grimsvotn volcano erupted.

- solid material of varying grain size ranging frovolcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- example: in 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- when an eruption melts glaciers and ice caps, serious flooding can result.
- example: Iceland in 1996 when the Grimsvotn volcano erupted.

- Volcanic Landslides.

- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- example: in 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- when an eruption melts glaciers and ice caps, serious flooding can result.
- example: Iceland in 1996 when the Grimsvotn volcano erupted.

- Volcanic Landslides.

- sea waves generated by violent volcanic eruptions such as those formed after the eruption of Krakatoa (Indonesia) in 1883.
- tsunamis from this eruption are estimated to have killed 36,000 people.
- (For details on tsunamis see the section on seismic hazards, pages 203–204 Hodder textbook)

- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- example: in 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- when an eruption melts glaciers and ice caps, serious flooding can result.
- example: Iceland in 1996 when the Grimsvotn volcano erupted.

- Volcanic Landslides.

- sea waves generated by violent volcanic eruptions such as those formed after the eruption of Krakatoa (Indonesia) in 1883.
- tsunamis from this eruption are estimated to have killed 36,000 people.
- (For details on tsunamis see the section on seismic hazards, pages 203–204 Hodder textbook)

- volcanoes emit gases which include sulphur. When this combines with atmospheric moisture, acid rain results.

- solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere.

- very hot (over 800°C), gas charged, high-velocity flows made up of a mixture of gas and tephra.
- speeds up to 700 km per hour.
- the Roman city of Pompeii (Italy) was destroyed in 79 AD by such flows from Mt Vesuvius

- Lava

- include carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
- In 1986, carbon dioxide emissions from the lake in the crater of Nyos (Cameroon) killed 1,700 people

- melted snow and ice as a result of the eruption combined with volcanic ash forms mud flows that can move down the course of river valleys at high speeds.
- example: in 1985, a lahar destroyed the Colombian town of Armero after an eruption of the volcano Nevado del Ruiz.

- when an eruption melts glaciers and ice caps, serious flooding can result.
- example: Iceland in 1996 when the Grimsvotn volcano erupted.

- Volcanic Landslides.

- sea waves generated by violent volcanic eruptions such as those formed after the eruption of Krakatoa (Indonesia) in 1883.
- tsunamis from this eruption are estimated to have killed 36,000 people.
- (For details on tsunamis see the section on seismic hazards, pages 203–204 Hodder textbook)

- volcanoes emit gases which include sulphur. When this combines with atmospheric moisture, acid rain results.

- the ejection of huge amounts of volcanic debris into the atmosphere can reduce global temperatures and is believed to have been an agent in past climatic change.

• they impact upon people and the built environment,
• killing and injuring people,
• burying and collapsing buildings,
• destroying infrastructure and bringing agricultural and
• other economic activities to a halt.