Volcanoes

                                   by Nick, Ian, Paul, Quinton

Largest Volcanic Eruptions

Table 1. Large eruptions in past 10,000 years.

 Table 2. Ancient Volcanic Eruptions

Reference: www.volcanolive.com

    Mount St. Helens,Washington

Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago and has been the most active volcano in the Cascade Range during the Holocene. Prior to 2200 years ago, tephra, lava domes, and pyroclastic flows were erupted, forming the older St. Helens edifice, but few lava flows extended beyond the base of the volcano. The modern edifice was constructed during the last 2200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the north flank, and were witnessed by early settlers. (Description from the SI/USGS Global Volcanism Program) 

     Kilauea Crater, Hawaii

Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions of Kilauea are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.

 Mount Tambora

 Indonesian  Gunung Tambora   dormant volcanic mountain on the northern coast of Sumbawa island, Indonesia. Now 9,354 feet (2,851 m) high, it erupted violently in 1815, when it lost much of its top and caused the death of 50,000 islanders and destroyed the homes of 35,000 more. Before that eruption Mount Tambora was 13,000 feet (4,000 m) high.

Emergency Information

What are the major health threats from a volcanic eruption?

The most common cause of death from a volcano is asphyxia or suffocation. Volcanoes emit hot gases, ash and rock that are powerfully destructive. People have died from volcanic blast when they were too close and failed to heed evacuation warnings. Other health concerns include floods, power outages, drinking water contamination, burns and respiratory illness.

How can I minimize risk and prevent injury from a volcanic eruption?

• Heed warnings and instruction from local authorities.

• Stay inside unless you are told otherwise.

• Wear goggles to protect eyes and a dust mask or damp cloth to protect nose, throat and lungs.

• Close windows, doors and dampers to minimize ash infiltration into the house.

• Review evacuation procedures and backup plans. Designate an emergency contact.

Where Volcanoes Mostly Form

Volcanoes mostly form around Tectonic Plates.  Some volcanoes form in the middle of the plates as hot spots.  Oceanic Plates can hit land plates and create volcanoes to.

How To Measure Volcanic Eruptions

Eruptions are measured by using the VEI ( Volcanic Explosivity Index ).  It records how much volcanic matierial is thrown out, how high the eruption goes, and how long it lasts. The scale goes from 0 to 8.  Each time the scale moves up one it is 10 times more powerful.

Effects On People And Society

Positive

1. Many people have homes on or near volcanoes.

2. Volcanic ash makes very fertile soil.

3. Most volcanoes erupt pretty infrequently (once every hundreds to thousands of years) .

4. Volcanoes are beautiful.

Negative

1. Destroys all your belongings

2. Might kill you

References

1. www.mysciencebox.org/plates

2. www.britannica.com/eb/article-9071099Mount-Tambora

3. www.volcanolive.com

4. www.emergencyinformation.org/guide/volcano

5. www.earlham.edu/~ethribe/web/tambora.htm

6. www.youtube.com/watch?v=488BkTUsMa4