USGS: http://earthquake.usgs.gov/research/data/slab/

Global Tectonics, Kearey, Klepeis, and Vine, 2009

Assessing the angle of subduction using GeoMapApp

Tonga-Kermadec slab model

Tonga-Kermadec P-wave velocity model

Content goal-Examine relationship between subduction angle, oceanic lithosphere age, and convergence rateHigher order thinking goals-Formulation of hypotheses-Analysis of large datasets-Synthesis of ideasSkills goals-Ability to access online databases and mapping programs

Description-Use GeoMapApp to examine datasets from four different subduction zones-Directed homework assignment to aid in interpretation of dataAssessment-Students submit completed homework assignment with answers to questions and images from GeoMapApp

GeoMapApp

Tonga-Kermadec earthquakes (1973–2009)

Collecting and organizing earthquake data

Collecting and organizing earthquake data

1) Which subduction zones have the largest earthquakes?2) Which subduction zones have the deepest earthquakes?3) Which subduction zones have the most earthquakes?

1) Based on these data, which subduction zones are most seismically active?

2) Based on the depth, magnitude, and frequency, discuss the possible prominent causes for the earthquakes at each of these subduction zones?

Tonga-Kermadec subduction zone interface with profile

Determining the dip angle of subduction

Tonga-Kermadec profile across subduction zone

Determining the dip angle of subduction

Determining the dip angle of subduction

1) What are the dip angles of subduction for each of these subduction zones?

1) Are these subduction dip angles what were expected? Explain.2) What could be causes for the differences in dip angle of

subduction for each of the regions?

Age of oceanic lithosphere in Tonga-Kermadec region

Assessing the factors that influence dip angle

Plate motion calculator:http://www.unavco.org/community_science/science-support/crustal_motion/dxdt/model.html

Assessing the factors that influence dip angle

1) What are the estimated convergence rates?2) What are the oceanic lithosphere ages?

1) Does the convergence rate influence subduction dip angle?2) Does the oceanic lithosphere age influence subduction dip

angle?

1) What other factors may have a significant influence on subduction dip angle?

2) Why do some subduction zones have deep earthquakes, whereas other subduction zones do not?

3) How do the factors that influence subduction dip angle also influence the type of accretionary orogen? Describe the possible types of accretionary orogens and determine what types of orogens these four subduction systems represent

Summary questions and synthesis of course material