Volcano Composition (5)

Volcano Composition (5) - Volcano Composition 1. What is...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Volcano Composition 1. What is magma? a. Varying composition i. Melt composition ii. Gas content iii. Amount of crystals iv. Responsible for viscosity and power 2. Primary control on melt viscosity a. Viscosity i. Resistance to flow, notion of internal friction b. Based on chemical bonding in melt c. Si and O are the most abundant in magmas, so largely controls viscosity d. SiO 2 tetrahedra forms bonds, which produces ‘chains’ these get tangles in flow and so produce resistance to shear stress e. Temperature changes viscosity- High T -> low viscosity f. Dissolved gas content changes viscosity i. High gas content -> low viscosity g. Numbers of crystals and bubbles changes viscosity i. Lots of crystals/bubbles -> high viscosity h. Magma viscosity ranges from 10 Pa-s (basalts) to 1,000,000 Pa-s (rhyolites) i. Water is around .001 ii. Why basalts flow and rhyolites explode i. Viscosity controls some features of post conduit transport i. Rate of travel of lava flows ii. Dome stability and collapse iii. Size of fragmented particles 3. Magmatic gas content
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
a. Main gases
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

Volcano Composition (5) - Volcano Composition 1. What is...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online