INTRODUCCIÓN

“No podéis preparar a vuestros alumnos para que construyan mañana el mundo de sus sueños, si vosotros ya no creéis en esos sueños; no podéis prepararlos para la vida, si no creéis en ella; no podríais mostrar el camino, si os habéis sentado, cansados y desalentados en la encrucijada de los caminos.”

Una presentación para clases bilingües 



MAIN VOLCANO TYPES

Although every volcano has a unique eruptive history, most can be grouped into three main types based largely on their eruptive patterns and their general forms. The form and composition of the three main volcano types are summarized here:

 VOLCANO
TYPE
 VOLCANO
SHAPE
 COMPOSITION
 ERUPTION
TYPE
 SCORIA CONE
 Straight sides with steep slopes; large summit crater
Straight sides with steep slopes; large summit crater
 Basalt tephra; occasionally andesitic
 Strombolian
 SHIELD VOLCANO
 Very gentle slopes; convex upward
Very gentle slopes; convex upward
 Basalt lava flows
 Hawaiian
 STRATOVOLCANO
 Gentle lower slopes, but steep upper slopes; concave upward; small summit crater
Gentle lower slopes, but steep upper slopes; concave upward; small summit crater
 Highly variable; alternating basaltic to rhyolitic lavas and tephra with an overall andesite composition
 Plinian




PRODUCTS OF ERUPTIONS


This section describes the volcanic features and phenomena generated by volcanic eruptions. The eruptive products are highly variaible and largely dependent on the composition, viscosity, and gas content of the erupting magma. Lava flows, for example, are more common in relatively non-explosive basaltic eruptions associated with shield volcanoes, scoria cones, and fissures. On the other hand, pyroclastic flows, lahars and voluminous tephra deposits are more common in explosive andesitic-to-rhyolitic eruptions associated with stratovolcanoes. Gaseous emissions are also examined, as are their harmful effects on both local and global scales.

Products of Eruptions

ERUPTION TYPES


This section describes the variability of eruption types, from quiescent lava emissions to extremely violent, explosive events. Eruption variability is largely related to magma composition and the amount of water present. The various eruption types are typically associated with particular volcano types. Shield volcanoes, for example, generate low-viscosity basalts associated with calm, effusive eruptions. It is common to find traditional names from classic eruptions to describe other eruptions and volcano forms: Hawaiian, Strombolian, Vulcanian, Surtseyan and Vesuvian (Plinian), for example. Although these names are somewhat poorly defined and subjectively applied, they are widely used in the volcanological literature.

Height of Eruption Column and Degree of ExplosivityHeight of Eruption Column and Degree of Explosivity -- Whereas the height of the eruption column can be measured directly in observed eruptions, it can also be estimated in ancient eruptions by measuring the geographic dispersal of the airfall tephra. The degree to which this tephra is fragmented provides a means to measure the explosiveness of the eruption. The diagram here (modified from Cas and Wright, 1988) demonstrates how these parameters will vary with eruption type. For more detailed information on these parameters, click on imageNote that hydrovolcanic eruptions (above dashed line) are generally the most explosive, but do not necessarily generate the highest eruption columns.


QUESTIONS

1. What is a caldera?
2. What is a lava lake?
3. What is a flank eruption?
4. What does subside mean?
5. What is a seismograph?
6. What is lava fountain? Braided lava?
7. What is sparkling light?
8. What is a lobe?
9. Does the word thoelitic basalt have any meaning to a K-6 student? (no)
10. How can gas cause splashing of lava?
11. What is a trough?
12. What is a cascade of spatter rampart?
13. What is the seismograph showing?
14. What are the geologists doing near the volcano?
15. What do you observe as the lava is flowing?
16. What is a viscous fluid?
17. What does incandescence mean?
18. What is a levee?
19. Where is Niagara Falls? (NY)
20. What is pumice?
21. What does lull mean?
22. What are cubic yards of lava?
23. Is Kilaeua a violent eruption?
24. What is a vent?
25. Can these people get hurt?
26. What is a spatter?
27. Spatter as large as bathtubs, how large is that?
28. What is an ocean surf?
29. How hot is 1200 degrees centigrade?
30. What is the color in lava caused by ? (Gas)
31. How does lava move?
32. What happens when the lava meets a tree?
33. What is a cinder cone?
34. What does drain downward to the vent mean?
35. What is a whirlpool? Backflow?
36. Where is downwind? What are these sticks? (trees)
37. How long will the lava lake take to cool?
38. Why was the town evacuated?
39. Where is the graben in the village?
40. What is a flank eruption?
41. What are basaltic dikes?
42. What are the geologists doing?
43. What is a conduit?
44. Which is steam, which is lava?
45. Where is the steam coming from?
46. Why does lava go to the oceans?
47. Why is there a steam cloud when lava hits water?
48. What is an aa flow? Pahoehoe flow?
49. Why are the Papyrus leaves stripped?
50. What is slowly consumed?
51. How can lava be extruded?
52. Where is the Washington monument?
53. Did the volcano make land?
54. How long does it take to recuperate from a volcanic eruption?


Vamos a investigar sobre diversos aspectos del paisaje.
Nos espera un viaje interesante.... 

 
COMENZAREMOS POR METERNOS EN LA PIEL DE UN VULCANÓLOGO E INVESTIGAREMOS SOBRE ESE APASIONANTE TEMA VISITANDO ESTOS ENLACES....   





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