Tsunami Damage to Infrastructure and the consequence for a small coastal community

Size: px

Start display at page:

Download "Tsunami Damage to Infrastructure and the consequence for a small coastal community"

Wilfred Norman
7 years ago
Views:

1 Tsunami Damage to Infrastructure and the consequence for a small coastal community Harry Yeh Oregon State University

2 The 2004 Indian Ocean Tsunami and The Previous (smaller) Tsunamis

3 The 2004 Indian Ocean Tsunami (Mw 9.2): Lhoknga 5 m Photo by Jose Borerro

4 Trubean, the 1992 Flores Tsunami (Ms 7.5)

5 The 2004 Indian Ocean Tsunami (Mw 9.2) The 1992 Nicaragua Tsunami (Mw 7.6) Vedaranniyan, India El Popoyo

6 The 2004 Indian Ocean Tsunami (Mw 9.2) The 1993 Okushiri Tsunami, Japan (Ms 7.2) Banda Aceh Photo by Jose Borerro Aonae

7 Individual tsunami effects on the coastal areas were similar to the previous tsunami events. What makes the 26 December 2004 event distinct is the extent of the affected area.

8 2004 Indian Ocean Tsunami Well engineered reinforced concrete structures were often survived Banda Aceh Nicobar Islands

9 Mega Tsunamis: ground shaking may last a long time, more than several minutes. Therefore, the ground at low-elevation may be liquefied much more than anticipated This is a lesson learned from the 2010 Chile Tsunami: more from Professor Scott Ashford

10 Seismic Data of the 2004 Indian Ocean Tsunami The duration of high-frequency energy radiation is about 500 sec. The rupture length is about 1200 km. (Ni, Kanamori, Helmberger, 2005)

11 Rupture Process of the 2004 Indian Ocean Tsunami (Ammon, et al., 2005)

12 Damage to Bridges

13 April 1, 1946 Aleutian Tsunami The earlier tsunami attack washed away one section of the bridge Hilo, Hawaii, 1946

14 A bridge jammed up with boats Nagappattinam, India: 2004

15 Scour Damage of the Bridge Kalpakkom, India, 2004

16 Impacts to Service Water Lines

17 Failure of a sewage line due to scour Kalpakkom, India, 2004

18 Flood due to Severe Subsidence

19 Coastal Subsidence: Nicobar Islands The 2004 Indian Ocean Tsunami

20 Salt (Sea) Water Effects

21 Impacts of Salt (sea) Water Discolored Vegetation Indira Point, Great Nicobar The 2004 Indian Ocean Tsunami Kovalam,India: The 2004 Indian Ocean Tsunami

22 Sediment and Boulder Transport

23 Tsunami Sediment Deposits Playa El Coco, Nicaragua, 1992

24 Tsunami Sediment Deposits Playa El Coco, Nicaragua, 1992

25 Boulder Deposits Trubean, Flores, 1992

26 Impacts to Topological Features

27 Devanaanpattinam India, 2004 Return-Flow Channel Incision

28 Return-Flow Channel Incision Sri Lanka, Kalutara Beach, 2004

29 Tsunami Scour Foundation Failure Momentary Liquefaction

30 Tsunami Scour Problems Roads The 2004 Indian Ocean Tsunami: Chennai

31 Scour Formation: 2004 Indian Ocean Tsunami Devanaanpattinam Runup height 4.1 m Scour depth 1.5 m Sri Lanka: photo by Patrick Lynett Scour depth 2.0 m

32 Scour Formation Capsized breakwater due to foundation failure at Aonae Port, Japan Scour depth: 4 m Foundation Failure: the 1993 Okushiri Tsunami

33 Scour Formation Kesen-numa, Japan: the 1960 Chile Tsunami Scour hole more than 8 m deep at the entrance to the port. After Takahashi et al. (1992)

34 Spatial Variation of Scour Depth α = 1/250. Maximum runup height 4.6 m Runup/drawdown process 16 min.!( d s ) = "p + % d -1$ 4i 2 erfc ' s # b d s, - ' & 2 c v "T (. * 0 * )/ 0. Offshore The maximum scour depth in the onshore area is less than 3 m. Pore-pressure driven scour does not occur farther inland than x = 300 m. The maximum scour depth is found to be 6.2 m deep at 450 m offshore

35 1 Quay-wall collapse Momentary Liquefaction Konakano, Japan: the 1960 Chilean Tsunami.

36 Tsunamis Often Induced Fire

37 1993 Okushiri Tsunami, Japan

38 Summary Difference between a mega tsunami and other significant tsunami. Reinforced concrete structures are often survived. Mega Tsunamis: ground shaking may last a long time, more than several minutes liquefaction problems. Bridge damage and failure. Ground subsidence. Salt water intrusion and its effects. Sediment and boulder transport. Impacts to geo-morphology. Tsunami Scour, Foundation Failure, and Momentary Liquefaction Fire and wind generation

39 A Small Coastal Community in Southern Oregon

40 Demographic Information Population 2, males and 1100 females Median resident age: 45 years Population density: 800 people per square mile

41 Hypothetical Cascadia Rupture A large earthquake of Mw 8.5 strikes the southern Oregon and the northern California coasts -- it s a rupture of the Cascadia. Happened during a winter day; therefore, no satellite image information would be transmitted, and very limited airborne reconnaissance would be possible. Ground shake lasts 2 minutes. Some liquefaction and landslide are likely. Goldfinger and others (2008)

42 Recall that, when the magnitude of the earthquake is sufficiently large (say > 7.5), individual tsunami effects on the coastal areas were similar regardless its magnitude. What makes it distinct is the extent of the affected area, and the duration of ground shake.

43 Hypothetical Tsunami Effects

44 The first tsunami arrives 20 minutes after the earthquake. Hypothetical Tsunami Effects Maximum runup height ~ 20 m (60 ft): This estimate might be a little high, but possible, considering the effect of the river outflow that may cause tsunami focusing. There will be 5 significant tsunami attacks in 90 minutes. The red line represents the estimated inundation area.

45 Hypothetical Tsunami Effects The entire area will be subsided by 2 m (6 ft). The largest subsidence of 6 m (20 ft) at the harbor. A series of tsunamis propagate along the river up to 20 km (12.5 miles) from the mouth. Immediately after the event, say 6 hours later, they found 50 people dead and 100 people missing.

46 Hypothetical Tsunami Effects Completely wipe out wood-frame buildings located west of the main road (HWY 101); many of the buildings east of the main road are also damaged heavily. Coastal sediments are deposited in the areas up to El. 17 m (56 ft). Significant scours are resulted in the area up to El. 5 m (16 ft). Because of the sediment (deposit) blockage and the severe subsidence, the river will be flooded to the south.

47 Hydro Information Ecological impacts due to salt (sea) water intrusion may become an issue. Ground water will become brackish and not suitable to drink.

48 Location Map Highway 101 would be damaged both north and south of the city: numerous landslides. In the case of the Mw 8.5 event, the affected area would be from Florence, OR to Crescent City, CA. A possible access to the coast from the inland would be HWY 199 via Northern California.

49 Bridge over the River Will the bridge fail? Probably not, but it won t be passable, because of the severe subsidence and liquefaction effects.

50 Scenario Only possible communication would be satellite phones. No port or airport runways can be used.

Chapter 7 Earthquake Hazards Practice Exam and Study Guide

Chapter 7 Earthquake Hazards Practice Exam and Study Guide 1. Select from the following list, all of the factors that affect the intensity of ground shaking. a. The magnitude of the earthquake b. Rather