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6 Quaternary Research for Extreme Natural Hazards: Lessons from March 11, 2011 Earthquake and Tsunami Koji Okumura (Hiroshima University)

7 March 11, 2011 Tohoku Earthquake and Tsunamis fatalities missing evacuees 15,578 5,070 45,242 as of 17 July as of 17 July as of 30 June mostly by tsunamis. ~10% of residents in inundated areas were killed (Ushiyama, 2011). Fukushima Daiichi (1F) nuclear accidents

8 magnitude vs fatalities (Bilham, 2010: modified) It is not the severest but was not supposed to have taken place.

9 Messages: THE PAST IS THE KEY FOR THE FUTURE our imperfect knowledge on the nature. FROM KNOWLEDGE TO ACTION. FAIL SAFE or FOOL-PROOF.

10 Knowledge on THE PAST is the;

11 However, most keys are broken,

12 most keys are broken, incomplete,

13 most keys are broken, incomplete, or lost.

14 Imperfect knowledge is our motivation of research. Scientific rigor and correctness is vital for us. most keys are broken, incomplete, or lost.

15 Imperfect knowledge is our motivation of research. Scientific rigor and correctness is vital for us. What we knew and what we did not? most keys are broken, incomplete, or lost.

16 IMPOSSIBLE = utter lack of knowledge 50 m slip 5 m+ tsunamis in high sea M8+ off Fukushima and Ibaraki MISSED INDICATION M 9.0 (Sumatra 2004) 1896 type tsunami in south Joban coastl uplift < modern subsidence FORESEEN = known but no time constraint 869 AD Jogan tsunami FORECASTED ground motion

17 tectonic background Ocean floor ages: Old Jurassic plate under Japan. M9 earthquakes: not uncommon

18 Subduction and intra-plate earthquakes are very frequent

19 subduction of pacific plate 8 cm/yr HERP(2005) subducting Pacific plate under Eurasian/North American Plates to ~600 km

20 Low-angle megathrust fault plane; cross section under Sendai

21 DPRI M 9.0 What is it? Intensity: half Japan was shaken strongly.

22 onshore deformation by GPS (GSI) In-SAR image of deformation (GSI)

23 Horizontal vertical GPS-transponder network by MSA

24 max 24 m slip observed onshore+offshore deformation by GPS (GSI) In-SAR image of deformation (GSI)

25 >50 m slip modeled fault model: onshore + offshore (GSI) fault model: onshore GPS(Liu et al.)

26 Mw 6.9 Mw 7.4 Mw 7.6 Ms 7.8 Kobe, 1995 (Horikawa, 1998) ISTL, Northern and Central (HERP, 2002) Izmit, 1999 (Delouis et al., 2003) Erzincan, 1939 (Ambraseys, 1988) Kobe 1995 RL ~3 m ISTL 841 LL 10 m Turkey 1999 RL 4 m Turkey 1939 RL 8 m 100 km 100 km ~M 8.3 ~M Off Eastern Hokkaido (Satake et al. 2005) Nankai Trough (HERP, 2001) Westernmost Kuril trench 17 c. ~ 7 m Nankai + Tonankai + Tokai: ~5 m ~M 9.3 Sumatra-Andaman, 2004 (Lay et al., 2005) M 9.0 ~50m 2011 Japan Trench Sumatra ~15 m Fault planes and maximum slip of large earthquakes.

27 cross section of Japan Trench (Tsuru et al., 2002) 40 m slip on 4 dipping thrust uplifts seafloor by 2.8 m. 40 m coseismic extrusion of the wedge uplifts by 3.5 m.

28 Vertical sea-floor deformation based on onshore GPS (GSI)

29 Ocean-bottom pressure gauges (TM1 & TM2: ERI) and GPS wave monitor (GPS: PARI) locations.

30 2 story, > 5m tsunami the base from Jogan source, high pulse from trench side. (Satake et al. 2011) Ocean-bottom pressure gauges (TM1 & TM2: ERI) and GPS wave monitor (GPS: PARI) records. time vs height.

31 TM1 1.5 km 440 km/h 29 km / 4.3 = 409 km/h TM2 1.0 km 360 km/h 27 km / 7.5 = 216 km /h GPS 0.2 km 160 km /h 20 km to Kamaishi Ocean-bottom pressure gauges (TM1 & TM2: ERI) and GPS wave monitor (GPS: PARI) records analyses. 3.8 ~23 km 16.5 ~100 km 6 ~16 km 18 ~50 km

32 CHIBA TOKYO Choshi IBARAKI Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Kamaishi IWATE AOMORI Hachinohe m run-up inundation and recent tsunami run-up and inundation (JSCE and CDMC; modified)

33 CHIBA TOKYO Choshi IBARAKI Joban raised coast with terraces Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Ishinomaki and Sendai coastal lowlands Kamaishi IWATE AOMORI Hachinohe Sanriku rias coast narrow alluvial plain under terraces extensive lowland for run-up narrow embayment and valley restrain water

34 CHIBA TOKYO Choshi IBARAKI Joban raised coast with terraces Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Ishinomaki and Sendai coastal lowlands Kamaishi IWATE AOMORI Hachinohe Sanriku rias coast TD = tsunami deposits run-up TD inundation deposit on alluvium, no run-up record 0 run-up TD inundation low but extensive run-up on lowland 0 run-up inundation TD wash out high run-up and inundation along channel 0

35 TOKYO CHIBA IBARAKI Choshi Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Joban Sendai Sanriku Kamaishi IWATE AOMORI Hachinohe m ~1000 fatalities no warning ~7500 fatalities Jogan warning: TD: 2 to 4 m a.s.l. run-up: ~10 m ~6500 fatalities 1896 preparedness 2011 run-up inundation No warning Jogan warning missed overwhelmed preparation

36 TOKYO CHIBA IBARAKI Choshi Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Joban Sendai Sanriku Kamaishi IWATE AOMORI Hachinohe m ~1000 fatalities no warning ~7500 fatalities Jogan warning: TD: 2 to 4 m a.s.l. run-up: ~10 m ~6500 fatalities 1896 preparedness 2011 run-up inundation F 0 Jogan tsunami deposits (red) and estimated run-up (Namegaya et al. 2011)

37 Long-term forecasts before March 11 -based on 400 year records long enough confidence from Nankai -focus on frequent M7 earthquakes -M7 asperities scattered in quasi-steady slip area tsunamis as the biggest -disregarded knowledge 869 Jogan tsunami (Sawai will introduce.) 1896 type tsunami earthquakes in south

38 No > M8 earthquake offshore Miyagi, Fukushima, and Ibaraki in > 1000 year historic records. Utsu ( ): Many large earthquake are known only in geologic records.

39 CHIBA IBARAKI FUKUSHIMA d c A1 MIYAGI IWATE AOMORI e2 b A2 e1 March 21 source area trench axis 2011 source was divided into 6 source areas

40 CHIBA IBARAKI FUKUSHIMA MIYAGI IWATE AOMORI d c A1 b A2 e2 e1 March 21 source area 2011 source was devided into 6 source areas, schematic diagram

41 CHIBA IBARAKI FUKUSHIMA MIYAGI IWATE AOMORI 1677 d e2 c 1938 A A1+A e1 (floating 1611, 1677, 1896) b no record no forecast Except A1 & A2, M7 earthquakes or uncertain sources were forecasted.

42 CHIBA IBARAKI The M8.0 forecast for A1+A2 and 1978 earthquake from A1 saved Sendai, Miyagi in Ground motion was not fatal in most places. FUKUSHIMA MIYAGI IWATE AOMORI d M 6.7- M 7.2 c M 7.4 A1 M 7.5 A!+A2 M 8.0 b no record no forecast M 8.0 e2 M 8.2 e1 characteristic floating Only Miyagi-ken-oki [A1, A1+A2] source area was charateristic.

43 CHIBA IBARAKI FUKUSHIMA M8.0+ A1+A2 MIYAGI IWATE AOMORI 20 m+ ~10 m M8.5+ M8.0? M8.5+ ~30 m ~10 m No indication in the history. It seems impossible to forecast. No evidence under the sea m m slip in 1896 Max. Slip (Satake et al. 2011) and rough estimates of energy release by segment.

44 CHIBA IBARAKI 869 Jogan earthquake was modeled on tsunami deposits (Namegaya et al., 2011) but M9.0 occurred before it is taken into forecast. Many more records are only onshore. FUKUSHIMA M8.0+ A1+A2 MIYAGI IWATE AOMORI ~10 m M m+ M8.0? M8.5+ ~30 m ~10 m 50 m m slip in 1896 Max. Slip (Satake et al. 2011) and rough estimates of energy release by segment.

45 1679 M7.5, 1841 M7.5, 1881 M7.9, 1941 M7.7, 2004 M9.2 Recurrence time: ~200 to 500 years Sumatra 2004 was quite indicative and did motivated paleo-tsunami studies.

46 Jogan 869 and 2011 inundation areas are similar.

47 TOKYO CHIBA IBARAKI Choshi Iwaki FUKUSHIMA 1F NPP Soma MIYAGI Sendai Ishinomaki Joban Sendai Sanriku Kamaishi IWATE AOMORI Hachinohe m ~1000 fatalities no warning ~7500 fatalities Jogan warning: TD: 2 to 4 m a.s.l. run-up: ~10 m ~6500 fatalities 1896 preparedness 2011 run-up inundation F 0 Jogan warning could have saved 1000s of lives, however, no action yet.

48 IMPOSSIBLE = utter lack of knowledge 50 m slip 5 m+ tsunamis in high sea M8+ off Fukushima and Ibaraki MISSED INDICATION M 9.0 (Sumatra 2004) 1896 type tsunami in south Joban coastl uplift > modern subsidence FORESEEN = known but no time constraint 869 AD Jogan type earthquake & tsunami FORECASTED ground motion

49 Finding the keys is our task. as 869 Jogan tsunamis Small pieces of information may lead to important finding beyond historic records most keys are broken, incomplete, or lost

50 Finding the keys is our task. As much as we find and reveal the past, the earth will be as much safer place from natural hazards and environmental changes. Fail-safe is indispensable for the lack of knowledge.

51 Quaternary Research is the key for the futrure. If we keep scientific rigor and correctness.

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53 Thank you.

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