The Impacts of the Cascadia Subduction Zone Earthquake on Oregon. Dr. Althea Rizzo Oregon Military Department Office Of Emergency Management

Transcription

1 The Impacts of the Cascadia Subduction Zone Earthquake on Oregon Dr. Althea Rizzo Oregon Military Department Office Of Emergency Management

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3 What are the geologic hazards in Oregon? Earthquakes Tsunami Volcanos

4 Earthquakes Earthquakes occur when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake.

5 Tsunami Tsunamis are generated when geologic events cause large, rapid movements in the sea floor that displace the water column above. The Pacific Coast is at risk both from locally and distantly generated tsunamis.

6 Why earthquakes? 100 years ago German geophysicist Alfred Wegener Theory of Continental Drift Landmasses of Earth fit together Evidence of fossils on opposite sides of the ocean

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8 1960s - Plate Tectonics

9 What are earthquakes?

10 Earthquake = fault rupture Rupture causes sudden release of strain energy Producing the shaking we experience as the earthquake Shock radiates out from rupture as seismic waves

11 Deep / Intraplate Deep quakes are usually less than M7.5. The 2001 Nisqually, Washington quake (M6.8). Damaging deep earthquakes occur every years. The seismic energy disperses over a much larger area. Damage is usually less than in a similar sized shallow quake. Few, if any, aftershocks occur. No tsunami expected, although landslides could trigger local tsunamis.

12 Shallow / Crustal Aftershocks are common and may cause further disruption. No tsunami expected, although there could be a local tsunami from landslides.

13 Shallow / Crustal Strong shaking is generally seconds, although it could be longer in localized areas. Shallow quakes are usually less than magnitude (M) 7.4.

14 Shallow / crustal (Incomplete) List of magnitude 4.0 or larger earthquakes in Oregon SSW of Coos Bay, OR WNW of Salem, OR SSE of Walla Walla, WA (felt in OR) S of Portland, OR S of Tillamook, OR ENE of Baker, OR WNW of Adel, OR WNW of Grants Pass, OR

15 Hazard -- Shallow / Crustal Map showing earthquakes in last 48 hours Small shallow earthquakes are recorded every day in Cascadia; damaging quakes occur every few decades.

16 Shallow / Crustal Most crustal quakes are shallow, Klamath Falls (6.0) and Scotts Mills (M5.6) in Damage can be very heavy in the area of the epicenter and along the fault.

17 Subduction Zone

18 Ok, back to Cascadia

19 What is the Cascadia Subduction Zone?

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21 Know your Cascadia Subduction Zone 600 miles long, from northern California to British Columbia Capable of producing very large earthquakes (M9+) that impact a wide area Similar in size and impact to the 2004 Sumatra earthquake Can produce devastating tsunamis 37% chance of a mega-thrust earthquake in the next 50 years *

22 Last Cascadia Subduction Zone earthquake occurred in 1700 When will the next one occur? We just don t know Average recurrence: 240 years (south of Cape Blanco) years (entire length) 190-1,200 years between EQ

23 Recurrence Mw ~9 500 yrs Mw yrs Mw yrs Mw yrs (Modified from Goldfinger et al. (in press) by adding magnitude estimates and some labels)

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25 Cascadia = Strong Shaking and Tsunami Strong Ground Shaking >8.0 Mw >2 min. shaking Tsunami within 15 to 25 minutes

26 What happens during a Cascadia Subduction Zone earthquake?

27 Strong ground shaking 1993 Molalla High School 2010 Haiti earthquake 2011 Tohoku earthquake

28 Shaking intensity CSZ in Lake Oswego Severe Strong Very Strong Source:

29 Compared to Japan 2011 EQ

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31 Coastal subsidence 2004 Sumatra People evacuate with small boats down a road flooded by the tsunami waves in the city of Ishinomaki in Miyagi prefecture_jiji PRESS_AFP_Getty Images

32 Coastal coseismic subsidence Cartoon of crustal deformation due to fault locking between earthquakes (top) and during an earthquake (bottom) Figure from Leonard et al 2003.

33 Coseismic subsidence Maps of GPS horizontal velocities (left) and the combined GPS vertical velocities with tide and leveling uplift rates (right). Vertical rates colored according to their magnitude. Warm colors indicate uplift. (Gina Schmalzle)

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35 Landslides Japan Landslides in Ferndale, WA 2010 Taiwan

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38 Astoria

39 Landslides in Jackson County

40 Liquefaction 1964 Niigata Liquefaction 2011 Christchurch Source: unknown 1964 Alaska

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43 Liquefaction Source:

44 Tsunami

45 Tsunami

46 Tsunami 2004 Indonesian tsunami 2011 Tohoku tsunami

47 Tsunami Local Caused by a subduction zone earthquake near the Oregon shore Distant Caused by a subduction zone earthquake far away from the Oregon shore

48 Distant Tsunami Arrives 4 + hours after the earthquake Lower damage and flooding than local tsunamis National Tsunami Warning System can warn you Warning and Advisory require protective action National Tsunami Warning Center hrs

49 Tsunami Evacuation Maps

50 Tsunami Inundation Maps

51 Tsunami Evacuation Modeling Beat the Wave How long does it take to get out of the bad zone?

52 Distant Tsunami Earthquake Far Away You won t feel the ground shake 4+ hours before waves arrive Limited Inundation

53 Distant Tsunami Beaches Harbors Rivers, Inlets Other low-lying areas

54 Distant Tsunami Tsunami Alert Messages National Tsunami Warning Center Alert Level Threat Action Information Statement Minor waves at most No action suggested Watch Danger level not yet known Stay alert for more info Advisory Strong currents likely Stay away from the shore Warning Inundating waves possible Full evacuation suggested

55 Distant Tsunami Notification Mass Notification Systems Social Media NOAA Alert Radio TV/Radio Sirens

56 Evacuation Before a Distant Tsunami WHO: Only those in the distant tsunami zone HOW: Probably by car WHERE:???

57 Re-entry After a Distant Tsunami Cancellation Message Re-enter with Caution Damage Harbors Beaches Low-lying areas Roads, Bridges Clean up

58 Local Tsunami Arrives minutes after the earthquake Much higher waves Much further inland penetration NOAA Tsunami Warning System ineffective Earthquake = Only Warning NO OFFICIAL WARNING! Self Evacuation required

59 What Tohoku teaches us about Cascadia

60 Probability versus Possibility Planning assumptions led to inadequate mitigation (Probable) Response planning was based on a recurrence of the 1896 Meiji Sanriku or 1960 Chile tsunamis. (Possible) 869 Jogan earthquake and tsunami significantly larger viewed as an outlier, a 1,000-year event that was low probability. The planning scenario supposedly depicted a highprobability 100 year event.

61 Assumptions have human impact 22,600 persons killed or missing nationwide 15,500 confirmed deaths 92.4% drowning 107,000 buildings collapsed, and another 111,000 partially collapsed BUT. 6.5 million people live within 200 miles of rupture zone

62 Initial earthquake magnitude estimations feeds previous assumptions Earthquake initially estimated at 7.9M Tsunami warnings issued based on this false information Subsequently, magnitude was raised to 8.9, then 9.0 Earthquake damage caused power and telecommunication outages which prevented people from getting updated tsunami warnings

63 Factors affecting survival of tsunami Physical factors geography and topography distance to high ground pre-disaster land use

64 Factors affecting survival of tsunami Human factors time of the event limited mobility caregiving behavior inaccurate conclusions drawn from past tsunami experiences instinct to protect property

65 Survival factors: disaster preparedness Regularly practiced drills Saw other people evacuating

66 Recommendations Enhance tsunami evacuation routes where high ground available Harden infrastructure Clear wayfinding Practice, practice, practice Build vertical evacuation refuges where high ground is not available.

67 Embed tsunami information in ambient built environment R. Wilson

68 Japanese emergency response challenges. Scale of the tsunami disaster Infrastructure damage prevented early reporting of damage and response needs. Access to satellite telephones was limited and inadequate to fill the communications gap. Highway and rail lines along the coast were destroyed, and access from the major highways to the west was blocked in many places by road damage and landslides. Marine access from the Pacific Ocean side of Iwate, Miyagi, and Fukushima prefectures was blocked on the first day by continuing tsunami action, and later by damaged dock facilities and floating debris. Fuel for vehicles and equipment was not available due to loss of power and damage to facilities.

69 Responders as victims Many jurisdictions lost political and response personnel, Facilities destroyed. Otsuchi Lost mayor, seven senior staff, and 31 other municipal employees in the tsunami. Minamisanriku Emergency operations and tsunami warning center was destroyed. 10 staff members survived by clinging to antennas on the roof.

70 Recommendations: Ensure Critical Continuity Relocate critical facilities out of inundation zone Retrofit critical facilities Prohibit building new critical facilities in inundations zone Ensure future construction of critical facilities meet the most robust standards

71 Emergency Shelter and Housing About 470,000 evacuees required shelter Local governments are responsible for post-disaster care and sheltering with assistance provided by the national government

72 Challenges to sheltering Dependent on local government officials, undamaged facilities, and logistic support. Pre-designated shelters destroyed. In some areas, food and water were not delivered for up to three days. Sheltering - mix of planned and ad hoc

73 In-place sheltering People with places to stay with family or friends or staying in their own homes Barrier to information and services as those living in shelters. Impacted lifeline services and other amenities

74 Recommendations Robust sheltering planning Bring the message home Personal preparedness Neighborhood prep Community prep

75 Aftershocks

76 Aftershocks Great Japan Earthquake 3 aftershocks > 7Mw within 40 minutes Aftershock area 500 km x 200 km More than 9,500 aftershocks as of March 2012

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78 Contact Information Geological Hazard Program Coordinator Althea Rizzo (503) ext