Tsunami Impacting Eastern Japan and Preparedness for Extraordinary Natural Disaster. Takehiko Fujita

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1 May 25, 2011 Tsunami Impacting Eastern Japan and Preparedness for Extraordinary Natural Disaster Takehiko Fujita Acting President Port and Airport Research Institute, Japan

2 Contents 1. Outline of the earthquake 2. Measured strong motion 3. Measured tsunami height 4. Evaluation of effects of previous countermeasures 5. Preparation against extraordinary tsunami

3 Source region of the earthquake Approximate source region of the earthquake. X denotes the epicenter. The pacific plate is subducting beneath the continental plate at the Japan trench. The earthquake occurred between the two plates.

4 A large number of aftershocks Distribution of aftershocks with M 5.0 Cumulative number of aftershocks (Japan Meteorological Agency) More than 400 aftershocks with M 5.0 have occurred as of May 13. (Japan Meteorological Agency) The size of the circle c indicates earthquake e magnitude. Five aftershocks with M 7.0 have occurred as of May 13.

5 Great amount of subsidence due to coseismic slip Horizontal displacement GPS Vertical displacement GPS 530 cm at Oshika 120 cm at Oshika (Geospatioal Information Authority of Japan) A great amount of horizontal and vertical displacement occurred due to coseismic slip. The Oshika Peninsula subsided about 120cm according to GPS observation by the Geospatial Information Authority of Japan. The sea floor around the epicenter moved 24m according to Japan Coast Guard. The movement was as large as 50m according to JAMSTEC.

6 A large number of strong motion data was successfully recorded by the Strong Motion Earthquake Observation in Japanese Ports

7 Design ground motions for Japanese Ports Two kinds of design ground motions are considered in the seismic design of Japanese port structures. The Level-1 design ground motion is defined as a ground motion with the annual probability of exceedance of 1/75. The Level-2 design ground motion is so called the worst case scenario ground motion.

Comparison with design ground motions - The case of Onahama Port - frequencies relevant to major damage to port structures It is quite natural that the observed ground motion exceeded the Level-1

8 Comparison with design ground motions - The case of Onahama Port - frequencies relevant to major damage to port structures It is quite natural that the observed ground motion exceeded the Level-1 design ground motion. The observed ground motion was close to the Level-2 design ground motion at frequencies relevant to major damage to port structures (0.3-1Hz). But at higher frequencies, the observed ground motion exceeded the Level-2 design ground motion. In the case of Onahama, the Level-2 design ground motion was based on a scenario earthquake with magnitude 6.5 (but just beneath the port). The appropriateness of the scenario should be investigated once more.

9 GPS-mounted wave buoy 40m 4.0 1m Aomori East 6.3 m Iwate North Iwate Central Iwate South 6.7 m Miyagi Central Miyagi North 5.6 m Fukushima 2.6 m highest crest Time (hour)

10 Tsunami height measured and estimated Run-up height Inundation height Estimated inundation height at the shoreline Tsunami height (m)

11 Damages of breakwater Landward Landward Landward

12 Kamaishi Tsunami Breakwater +6m Meiji Sanriku Earthquake (1896) 5 m +6 m 2.8 m +4 m Less than 0.5 m Tsunami breakwater Tsunami seawall

13 Simulation results for the ToHoku Earthquake in 2011 The 2011 off the Pacific Coast of Tohoku Earthquake (2011) Without Breakwater This tsunami simulation is conducted by Storm Surge and Tsunami Simulator in Oceans and Coastal Areas (STOC), which is developed by PARI. With Breakwater

14 Effect of breakwater Wa ater surface elevation (m) Without Breakwater Arrival time 6 minutes delay (tsunami height of 4 m) with breakwater without Tsunami height 13.7 m 8.0 m With Breakwater Tsunami height (m) Time after earthquake (min)

15 Effect of breakwater Without breakwater Tsunami height 13.7 m Run-up height 20.2 m 4-m-height seawall 28 min for overtopping With breakwater Run-up height Tsunami height Tsunami height ht m 8.0 m 10.8 m Tsunami Breakwater 4-m-height seawall 36 min for overtopping

16 Tsunami damages Quay damaged by the combination of earthquake and tsunami (Soma) Scattered containers (Sendai) Tilted floating dock (Kuji) Collapsed crane (Kashima)

17 Tsunami damages Drifted tank trucks (Sendai) Ship drifted in a town (Kesennuma) Destroyed seawall (Taro) Smashed oil tank and oil spill (Kesennuma)

18 Tsunami damages Washed vehicles and debris (Kamishi) Broken and tilted buildings (Onagawa) Burned wooden houses and vehicles (Ishinomaki) Piles were e pulled out. Collapsed building (Onagawa)

19 March 13 Liquefaction remediation Sendai Airport March 18 The liquefaction counter measure of runway had ended, d however, the taxiway was being prepared. Infiltration Solidification X-Jet Grouting River culvert

20 Liquefaction remediation Sendai Airport March 20 March 18 Improved runway Apron and Boarding bridge The runway keeps Serviceability just after the March 20 Earthquake. However, It took one week to cleanup the debris due to Tsunami. The operation of the passenger plane restarted on April 13. There are serious subsidence, uneven settlements and clacks on the surface of un-improved taxiway. It lost the Serviceability and the Reparability. Un-improved taxiway

21 Sendai Port: Base Isolated Gantry Crane 4 Gantry Cranes : 2 base-isolated cranes 2 non-base-isolated cranes Damage occurred in one non-base-isolated crane Direction of Land and Sea ISOLATOR アイソレ- タ横行方向ダンパ Oil Dumper Trigger Pin Parallel Motion Link 平行リンクシアピンモ - メント受けロ - ラ Base Isolation system Moment Transmission Bearing Patent holder : PARI and Mitsui Engineering & Shipbuilding Co, Ltd. Base-isolated cranes: No structural damage

22 Future Improvement in Information Network Mutsu-Ogawara Port Hachinohe Port Kuji Port Tohoku District Miyako Port Ofunato Port Kamaishi Port Shiogama Port North Miyagi Sendai New Port Central Miyagi Soma Port Present System strong motion observation site GPS buoy coastal wave gauge tide gauge house land station land station land station Idea for Future System earthquake, tsunami, communication disturbance NTT telephone line, on demand Tohoku B* and Port Offices * Ports and Airports Division, Tohoku Regional Development Bureau Toward redundant system!! PARI Onahama Port Packet data transmission - Mobile phone (NTT FOMA, etc.) - Satellite phone (INMARSAT, Iridium, etc.) National backup center? Kanto District PARI Hitachi-naka, Ibaraki Port Kashima Port strong motion sensor GPS Buoy coastal wave gauge tide gauge damaged or lost sensor strong motion observation site GPS buoy coastal wave gauge tide gauge house land station land station repeater station NTT telephone line, automatically Tohoku B* and Port Offices PARI

23 Recommended countermeasures against tsunami Level 1 Design tsunami Largest tsunami in modern times (return period: around 100 years) Required performance To protect human lives To protect properties To protect economic activities Level 2 One of the largest tsunamis in history To protect human lives To reduce economic loss, (return period: around 1000 years) especially by preventing the occurrence of severe secondary disasters and by enabling prompt recovery Disaster prevention facilities such as seawalls should be safe against Level 2 tsunami. At least, in the event of Level 2 tsunami, the deformation of these facilities have to be not so large to maintain the performance to reduce tsunami.

24 Issues on Preparedness Against Extraordinary Tsunami Hazard Map To prepare hazard maps and scenarios against tsunamis of levels 1 & 2. Evacuation To develop and implement the real-time tsunami prediction based on the data observed by GPS-mounted wave buoys. To establish secure and reliable warning systems and evacuation routes in consideration of blackout and traffic. To prepare shelters that t are secure even against level l 2 tsunami. Urban Plan To make higher grounds such as artificial grounds, embankment, and reclamation lands. To make houses rigid. Recommended material is not wood but concrete. To make local people to construct their houses at hill areas. To provide access from hill areas to commercial areas in coastal zone. To build tall buildings that have residential areas in upper floors and commercial areas in lower floors.

Tsunami Impacting Eastern Japan and Preparedness for Extraordinary Natural Disaster. Takehiko Fujita

February 22, 2012 Tsunami Impacting Eastern Japan and Preparedness for Extraordinary Natural Disaster Takehiko Fujita Executive Director Port and Airport Research Institute, Japan Contents 1. Outline of