Seismology Related Reading

Question 1

Between 2004-2011, how many great earthquakes (Mw >8) have occurred?

Answer 1

7 (Lay, 2011)

Question 2

What is the rate of great earthquakes between 2004-2011 and the rate of great earthquakes over the last century?

Answer 2

1.9/yr vs 0.7/yr (Lay, 2011)

Question 3

When was the last period of great earthquake activity?

Answer 3

1950’s to 1960’s (Lay, 2011)

Question 4

Name the three greatest earthquakes which occurred in the last period of great earthquake activity

Answer 4

Kamchatka (1952, Mw: 9.0), Chile (1960, Mw: 9.5), Alaska (1964, Mw: 9.2)

Question 5

What did all the recent great earthquakes have in common?

Answer 5

Each had some surprise, and acted in a way which was by no means predicted

Question 6

Which authors observed sand boils in the form of sand volcanoes in the 2005 Kashmir Earthquake?

Answer 6

Sahoo et al, 2007

Question 7

What are the three conventional liquefaction phenomenon, reviewed by (Authors)?

Answer 7

Sand boiling, ground cracking, lateral spread (Huang and Yu, 2013)

Question 8

According to (Authors) what happens to the pore water pressure of saturated sand during an earthquake?

Answer 8

Increases rapidly (Huang and Yu, 2013)

Question 9

According to (Authors) what happens to stress in saturated sand during an earthquake?

Answer 9

Reduces to zero (Huang and Yu, 2013)

Question 10

What are the four most favorable conditions for liquefaction occurrence according to (Authors)?

Answer 10

Loosely packed, coarse silt to fine sand, saturated with ground water, shallow depths (Huang and Yu, 2013)

Question 11

What are the two different mechanisms for sand boiling according to (Authors)?

Answer 11

Flat-cone sand volcanoes and eruption through pre-existing cracks (Huang and Yu, 2013)

Question 12

What is sand boiling (Authors)?

Answer 12

Eruption of sand and water to surface (Huang and Yu, 2013)

Question 13

Give an example where sand boiling occurred through pre-existing cracks (Authors in Authors)

Answer 13

2011 Yingjiang earthquake (Yao et al, 2011 in Huang and Yu, 2013)

Question 14

Why do ground cracks (as a form of liquefaction) occur during earthquakes according to (Authors)?

Answer 14

Uneven distribution of material in soil layer (Huang and Yu, 2013)

Question 15

Name an example where ground cracks have formed (as a form of liquefaction) during an earthquake (Authors in Authors) and their approximate widths

Answer 15

2008 Greece EQ, 2-8 cm (Margaris et al, 2010 in Huang and Yu, 2013)

Question 16

What is lateral spread according to (Authors)?

Answer 16

Permanent horizontal liquefaction induced ground displacement (Huang and Yu, 2013)

Question 17

Where does lateral spread most commonly occur, according to (Authors)?

Answer 17

Parallel to course of rivers (Huang and Yu, 2013)

Question 18

Give and example of lateral spread during an earthquake (Authors in Authors)

Answer 18

2008 Greece EQ, incriments increased towards the sea with a maximum spread of 60 cm (Margaris et al, 2010 in Huang and Yu, 2013)

Question 19

Name the 5 types of new liquefaction phenomena which occurred during 21st century EQ’s according to (Authors)

Answer 19

Liquefaction in areas of moderate seismic intensity, Liquefaction of gravelly soils, Liquefaction of deep-level sandy soils, Re-liquefaction in aftershocks, Liquid behavior of unsaturated sandy soils (Huang and Yu, 2013)

Question 20

What is the normal assumption for earthquake magnitude and epicentral distance in relation to magnitude (Authors in Authors)?

Answer 20

Larger magnitude and closer to epicenter is generally were liquefaction occurs (Huang and Yu, 2013)

Question 21

Give an example of where liquefaction occurred at a smaller magnitude than expected (note intensity scales) (Authors in Authors)

Answer 21

2008 Wenchuan Earthquake, VI on modified mercalli, where VI or less are noted as free from liquefaction. (Chen et al, 2009 in Huang and Yu, 2013)

Question 22

Give an example of where liquefaction occurred at a distance further from the epicenter than expected (Authors in Authors)

Answer 22

2011 Tohoku Earthquake – Liquefaction occurred 350-400km away in Tokyo bay (Bhattacharya et al, 2011 in Huang and Yu, 2013)

Question 23

What are the two main reasons why liquefaction occurred 350-400km away from the epicenter in Tokyo bay during the 2011 Tohoku EQ (Authors in Authors)?

Answer 23

(1) deposits were fill materials/young alluvium (2) duration of EQ was up to 300 s (Bhattacharya et al, 2011 in Huang and Yu, 2013)

Question 24

Why was it that gravely soils were once thought to be unliquefiable (Authors)?

Answer 24

Because they had high hydraulic conductivity (Huang and Yu, 2013)

Question 25

Give an example where gravely soils were liquefied (grain sizes) (Authors in Authors)

Answer 25

2008 Wenchuan EQ, mean grain sizes of 1 to >30mm (Cao et al, 2011 in Huang and Yu, 2013).

Question 26

What is thought to be the reason as to why gravely soils were liquefied during the 2008 Wenchuan EQ (Authors in Authors)?

Answer 26

The soils were shallow and loose (Huang and Yu, 2013)

Question 27

So far, liquefaction has not been found deeper than __ m

Answer 27

30m

Question 28

What are the two coupling factors thought to contribute to very deeply occurring liquefaction (Authors)?

Answer 28

High amplitude ground motion with long duration (Huang and Yu, 2013)

Question 29

How deep was liquefaction found in the Tohoku 2011 earthquake? (Authors in authors)

Answer 29

12-16 m (Bhattacharya et al, 2011)

Question 30

Up to what depths is liquefaction normally expected to occur? (Authors)

Answer 30

Up to 6 m (Huang and Yu, 2013)

Question 31

What would a vertical profile of a region at high risk of liquefaction look like (two layers)(Authors)

Answer 31

A saturated sandy layer overlain by confining medium such as clay or silt (Huang and Yu, 2013)

Question 32

What is the most common feature of re-liquefaction during aftershocks? (Authors in Authors)

Answer 32

Stacked sand volcanoes re-liquefying, small holes developing in larger holes (Huang and Yu, 2013)

Question 33

Give an example of re-liquefaction during an aftershock (Authors in Authors)

Answer 33

2008 Wenchuan EQ, re-liquified during Ms 6.4 (Chen et al, 2009 in Huang and Yu, 2013)

Question 34

In what situation can unsaturated soil liquefy fully?

Answer 34

pore air and water pressure = confining pressure (Huang and Yu, 2013)

Question 35

What are the three main ways damage can be induced on buildings by liquefaction (Authors)?

Answer 35

Ground subsidence, lateral spread, buoyancy (Huang and Yu, 2013)

Question 36

What are the two ways that damage caused by buoyancy during liquefaction be avoided? (Authors in Authors)

Answer 36

Ground improvement methods, anchoring of utilities (Huang and Yu, 2013)

Question 37

According to (Authors) how many fires were alight at one point in Kobe, 1995?

Answer 37

148 (NFPA, 1995)

Question 38

What did (Authors) state as a potential ignition source during the Kobe 1995 EQ?

Answer 38

Open fires in houses commonly used for cooking and heating (NFPA, 1995)

Question 39

Name three factors which worsened the fire situation in Kobe according to (Authors)

Answer 39

Tightly knit houses made from lightwoods, compromised water supply, limited road access

Question 40

Name three reasons why fires were not as bad as they could have possibly been according to (Authors)

Answer 40

Low windspeed up to 3 days after EQ, Kerosene fires used for heating generally turned off due to early hour of EQ, Some buildings stood in the open/had structures were harder to penetrate (NFPA, 1995)

Question 41

Name a case study where landslides triggered by earthquakes proved fatal (Authors)

Answer 41

Mount Huascaran, Peru, 1970

Question 42

What was the death toll at Mount Huaschran, Peru?

Answer 42

25,000

Question 43

Where did most of the deaths occur?

Answer 43

Towns of Yungay and Ranrahircha

Question 44

The town of Yungay is ___km from Mount Huaschran

Answer 44

16.2km

Question 45

Give an example where a flood has been caused by a landslide into a water body, and explain what happened, number of fatalities.

Answer 45

1933 Deixi, China: Landslide damed river to 255m high, then the dam failed. 2500 drowned.