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Goh Cheng Leong Chapter 3: Vulcanism and Earthquakes (Physical and Human Geography)

Certificate Physical & Human Geography Goh Cheng Leong

Chapter 3: Vulcanism and Earthquakes

Volcano

Volcano

Intrusive Landforms

  • Laccolith
  • Lopolith
  • Phacolith
  • Batholith
  • Sills
  • Dykes

Origin

  • Vulcan – God of Underworld – furnace below Volcano in Sicily
  • At zones of weakness – fold or fault
  • Temperature increase for for 65 feet
  • Magma has gases - Sulphur, Nitrogen , Chlorine – through the vent or opening

Types of Lava

  • Acidic – light colored, highly viscous, flow slowly, steep-sided, pyroclasts, bombs, spine or plug form crater as Mt. Pelee (Martinique) , plug remains in Puy de Dome, France
  • Basic – hottest, highly fluid, Fe & Mg, lack silica, dark color, highly fluid, flow quietly, thin sheets and spread over large area – shield or dome

Types of Volcano

  • Active - Kilauea
  • Dormant - Mauna Kea
  • Extinct - Kohala

Extrusive Landforms

  • Lava Plains and Basalt Plateaux – fluid – Snake basin, USA; Deccan; Iceland
  • Lava domes or shield volcanoes – volcanic cones – Mauna Loa & Kilauea (caldera with active vent pours forming lava pit of Halemaumau)
  • Ash & cinder cones – less fluid – large crater & steep slope – small volcano in groups – Mt. Nuovo (Naples) & Mt. Paricutin (Mexico)
  • Lava tongues & lava dammed lakes – confined in valleys
  • Lava bridges
  • Lava tunnels
  • Volcanic dust – fine particles
  • Dust and Ash – black snow
  • Pyroclast – coarse fragments – cinders/lapilli, scoria, pumice and volcanic bombs

Composite Cones

  • Highest and most common
  • Called Stratocones – main conduit and subsidiary dykes and pipes
  • Mt. Etna (Sicily, Italy)
  • Mt. Stromboli (Lighthouse of Mediterranean)
  • Mt. Vesuvius
  • Mt. Fiji
  • Mt. Popacatapetl
  • Mt. Chimborazo

Mt. Vesuvius

  • Bay of naples – erupted 79 AD
  • Parasitic cone
  • White hot lava
  • Cauliflower form – pyroclasts & ashes
  • City of Pompeii – buried beneath 25 feet of ashes
  • City of Herculaneum – mudflow – 50 feet thick
  • In 1631 – avalanche with red hot debris – ruined 15 towns and killed 4,000, 1 foot thick ashes in Naples

Mt. Krakatau

  • August 1883
  • B/w Java & Sumatra
  • Dense black cloud – 20 - 50 miles high
  • 2 ⁄ 3rd island collapsed
  • Caldera formed
  • Explosion heard 3000 miles away
  • 36,000 people drowned in coastal areas
  • Erupted again in 1927 – pushed cinder cone from submarine floor of 220 ft ASL by 1952
  • Anak Krakatau or Child of Mt. Krakatau formed

Mt. Pelee

  • West Indies
  • Erupted in 1902
  • White hot lava
  • Superheated stream
  • Nuee ardente (glowing avalanche)
  • 30,000 except 2 killed in . Pierre (capital of Martinique)
  • Spine formed by pasty lava- solidified
Mount Pelee
Circum-Pacific Belt and Alpine-Himalayan Belt

Distribution of Volcanoes

  • Circum-Pacific ring of fire or Pacific ring of fire – 2 ⁄ 3rd volcanoes
  • 100 active volcano in Philippines, 40 in Andes, 35 in Japan, 70 in Indonesia
  • Pacific coast – more active (Aleutian, Java, Sumatra, Kamchatka, Solomon, New Hebrides)
  • Atlantic coast – less active (Madeira, Ascension, Helena, Cape Verde, Canary)
  • Iceland & Azores – active
  • Mediterranean – associated with Alpine folds (Vesuvius, Etna, Stromboli, Volcano)
  • Himalayas – no active volcanoes
  • Africa – East African Rift valley – active (Cameroon) , extinct (Kilimanjaro and Kenya)

Geyser & Hot Springs

  • Geyser – fountain of hot water – Iceland, Rotorua (N. Island, New Zealand) , Yellowstone National Park (USA) – Old Faithful erupts every 63 minutes
  • Hot Springs – dissolved minerals – Iceland, Hawaii, Japan
Geyser and Hot Springs

Earthquakes

  • 50,000 tremors per year
  • Minor – vibrations
  • Major – faults
  • Tidal waves – tsunamis
  • Fire
  • Building collapse
  • Fissures open- surface waves
  • Infrastructure affected
  • Measured seismograph

Major Earthquakes

  • 1755: Great Libson (Atlantic west) – tidal waves – 60,000 died
  • 1923: Tokyo & Yokohama –
  • 1906: San Francisco
  • 1920: Kansu, China – 2 lakh died & 1 lakh cave dwellers in 1927 affected
  • 1960: Agadir, Morocco: 10,000 died
  • 1968: Kakh, E. Iran

Distribution of Earthquakes

  • Coincides with volcanoes
  • 70 %: Circum-Pacific belt
  • 20 %: Mediterranean-Himalayan belt

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