Earthquakes - Physical features

Question 1

Tectonics of Haiti

Answer 1

Conservative plate boundary (North American and Caribbean)

Question 2

Tectonics of Sichuan

Answer 2

Longmenshan Fault, caused by a destructive plate boundary (Indian and Eurasian) - also added pressure from reservoir construction (New York Times)

Question 3

Tectonics of Tohoku

Answer 3

Destructive plate boundary (Eurasian and Pacific - joeblakey.com)

Question 4

Which plate margins are likely to cause more suffering? Fact to back this up?

Answer 4

Destructive or conservative. The 20 deadliest earthquakes since 1990 all occurred at either a destructive or conservative plate boundary - suggests greater pressures build up at these margins

Question 5

Magnitude and depth of Haiti

Answer 5

Magnitude: 7 (Geofile)
Depth: 8km

Question 6

Magnitude and depth of Sichuan

Answer 6

Magnitude: 7.9 (USGS)
Depth: 10km

Question 7

Magnitude and depth of Tohoku

Answer 7

Magnitude: 9 (Geofile)
Depth: 24km (USGS)

Question 8

Why does earthquake depth matter?

Answer 8

Shallower earthquakes tend to result in greater intensity of surface shaking, and often cause greatest loss of life and damage to property (all three case studies are identified as shallow earthquakes by USGS)

Question 9

Secondary hazards in Haiti

Answer 9

A set of small, local tsunamis

Question 10

Secondary hazards in Sichuan

Answer 10

Heavy rains were induced, causing mudslides and more building destruction (Keio University report)

Question 11

Secondary hazards in Tohoku

Answer 11

Large tsunami, caused by a 5-8m upthrust off the east coast. It reached a maximum height of 39m at Miyako city and travelled up to 10km inland

Question 12

Liquefaction in Haiti

Answer 12

Occurred extensively along the coastline around Port-au-Prince bay, and was responsible for the severe damage at the port

Question 13

Liquefaction in Sichuan

Answer 13

Weak rock had built up in the Sichuan Basin, which underwent liquefaction and amplified the effects of the shaking

Question 14

Liquefaction in Tohoku

Answer 14

Occurred in areas of reclaimed land around Tokyo, damaging over 1000 buildings

Question 15

Why is liquidation a hazard?

Answer 15

Building foundations become unstable and slopes become vulnerable to mass movement. It’s a major contributor to urban seismic risk