Mind Map on Volcanoes, created by GoreCat97 on 03/02/2015.
Mind Map by GoreCat97, updated more than 1 year ago
Created by GoreCat97 over 8 years ago

Resource summary

  1. Landscape of vulcanity
    1. Extrusive activity
      1. Intrusive activity
      2. Locations
        1. Subduction boundaries
          1. Sea-floor spreading centres
            1. Rifting on continental plates
            2. Hotspots
              1. Individual plumes of magma rise to the crust
            3. Eruption styles
              1. Hawaiian(Haw)
                1. Basaltic--> highly fluid lava
                  1. Low gas content --> non explosive/violent eruptions--> effusive lava flows
                    1. Shield Volcanoes eg Kilauea, Hawaii and Mauna Loa, Hawaii
                    2. Strombolian(Strom)
                      1. Moderate gas content--> slightly more explosive than Hawaiian eruption
                        1. Cinder cones volcanoes eg Mount Etna
                          1. Basaltic/Andesitic--> more viscous lava than Hawaiian
                          2. Vulcanian(Vul)
                            1. High amounts of gas-->steam explosions--> release old material from central vent
                              1. Viscous basaltic to rhyolitic
                                1. Tephra dispersed into wider areas than Haw/Strom
                                  1. Cinder cones & Stratovolcanoes eg Vulcano, Italy
                                  2. Pelean(Pel)
                                    1. More viscous andesitic & rhyolitic magma than Vul
                                      1. Upward escape of explosive gasses prevented by solidified lava--> forces way out--> nuee ardente
                                        1. Stratovolcanoes eg Mount Mayon
                                        2. Plinian
                                          1. Gas-rich eruptions--> intensely violent --> wide disperse of pyroclastic materials
                                            1. Stratovolcanoes
                                          2. Primary Hazards
                                            1. Lava flows
                                              1. Depends on vicosity
                                                1. Steepness of ground
                                                  1. Rate of prodn level
                                                  2. Pyroclastic flows
                                                    1. Destroys everything in path
                                                      1. Most dangerous: Lateral blast
                                                        1. Lead to lahars by damming streams (water mix with rock fragment)--> rush downstream
                                                        2. Tephra & ash fall
                                                          1. Block sunlight--> temporary cooling of atmospheric temperature
                                                            1. Ash disrupts lives of ppl more than other volcano hazards bc leads to low economic activity by reducing visibility and is slippery
                                                            2. Volcanic gasses
                                                              1. Sulphur dioxide gas--> acid rain & air pollution
                                                                1. Carbon dioxide > 30% is lethal
                                                              2. Secondary Harzards
                                                                1. Lahar
                                                                  1. Volcanic Landslide
                                                                    1. Tsunamis
                                                                      1. Earthquake
                                                                        1. Torrential Rain
                                                                          1. Atmospheric effects
                                                                          2. Mitigation
                                                                            1. Lava Flow Dams
                                                                              1. Redirect lava flow. Rely on the fact that basaltic lava do not behave like bulldozers. Can contain basaltic lava. Small flow to prevent lava from getting down to lower parts of volcano. Big flow--> spill down but give sufficient time for ppl to evacuate
                                                                              2. Hazard Mapping
                                                                                1. Long term planning. Show areas most likely to be affected by diff types of volcanic activity. Indicate relative degree of hazard occurring. Good for land-use & effective emergency-response measures--> will save many ppl and avoid dmgs to property
                                                                                  1. However, if met with strong opposition from economic interests> will likely be produced not long b4 eruption> insufficient time for proper dissemination of map to public
                                                                                  2. However, not sure of the accuracy for (a) size of eruption (b) duration of eruptive activity (c) extent of topographic changes (d) specific vent location
                                                                                  3. Educating the public
                                                                                    1. Lessen physiological and physical impacts of eruption on the public. Warnings can be better understood if public understands nature of hazard. We can also use hazard map to educate
                                                                                    2. Crisis Response
                                                                                      1. Emergency evacuation plans are developed to ensure safest and most efficient evacuation time should any natural disasters occur
                                                                                        1. However, inadequacy of the community in responding to the imminent disaster was compounded by the failure of local authorities to respond in a timely manner. Complacency. Chain of command and sometimes a meeting along the way. Eg Nevado del Ruize
                                                                                    3. Monitoring
                                                                                      1. Tilt Meters
                                                                                        1. Monitor deformation caused by upward movement of magma underneath surface
                                                                                        2. Eruption Recurrence Interval Prediction (Long Term)
                                                                                          1. A cycle may be evident eg Hawaii displays regular eruptive sequences w definable intervals
                                                                                            1. Ascertain historic style of eruption. Determine the volcano's eruption interval.
                                                                                            2. Physical Anomalies and Precursor Phenomena
                                                                                              1. Ground deformation as magma moves into a volcano. Tilt meters measure changes in angle of volc's surface
                                                                                                1. Volcanic gasses such as hydrogen chloride & sulphur dioxide emitting from volcanic vents
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