A Short Story About Earthquakes Ein kurzer Vortrag über Erdbeben

Transcription

1 A Short Story About Earthquakes Ein kurzer Vortrag über Erdbeben Wolfgang Rattay Reuters BBC Kurt Decker Universität Wien Department für Geodynamik und Sedimentologie

2 The short sumary of a short story What causes an earthquake? Are earthquakes more frequent today than they were in the past? Are earthquakes predictable? Magnitude or intensity - what is useful for planning rescue missions? Where to get real-time data for the planning and preparation of rescue missions?

3 SHARE (Basili et al., 2013)

4 What causes an earthquake? How does it work? A very short introduction to earthquake physics

5 M = 6.4 Hualien (Taiwan), 6. Februar 2018 M = 6.2 Norcia-Amatrice (IT), 15. November 2016 M = 7.1 Christchurch (NZ), 4. September 2010 M = 7.2 Baja California (USA), 4. April 2010

6 Earthquake physics Frictional plasticity / Elastisch-Reibungsplastisch Elastic Rebound Model (Benioff, 1964) (Baice & Byerlee, 1966) Rate and state variable friction / Reibungsstabilitätsregime: the Dietrich-Ruina or Slowness Law t = [m 0 + a ln (V/V 0 ) + b ln (V 0 q/l)] s t Sheastress s Effective normal stress V Slip velocity V 0 Reference velocity m 0 Static friction L Slip distance q State variable: dq / dt = 1 qv/l a, b Material-dependent constants

7 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

8 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

9 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years

10 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

11 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

12 The active Vienna Basin Fault between the city of Vienna and Bratislava Coseismic deformation Seconds - minutes 1-2 mm / year

13 The active Vienna Basin Fault between the city of Vienna and Bratislava Postseismic deformation Weeks - months 1-2 mm / year

14 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

15 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

16 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

17 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

18 The active Vienna Basin Fault between the city of Vienna and Bratislava Interseismic deformation 10² - 10³ years 1-2 mm / year

19 The active Vienna Basin Fault between the city of Vienna and Bratislava Coseismic deformation Seconds - minutes 1-2 mm / year

20 The active Vienna Basin Fault between the city of Vienna and Bratislava t = [m 0 + a ln (V/V 0 ) + b ln (V 0 q/l)] s Postseismic deformation Weeks - months 1-2 mm / year

21 Are earthquakes predictable? t = [m 0 + a ln (V/V 0 ) + b ln (V 0 q/l)] s No physics are too complicated and not (yet) properly understood

22 Are earthquake probabilities predictable? Earthquake hazard maps and their limitations

23 GSHAP (Giardini, 1999)

24 Probing the predictions of hazard maps GSHAP (Giardini, 1999) Wyss & Rosset, Nat. Hazards, 2013: Intensities reported for the last 60 earthquakes with M 7.5 were all significantly larger than expected, based on the hazard map (by 2.3 intensity units for the 12 deadliest earthquakes).

25 Probing the predictions of hazard maps Stein et al., Wenchuan, M = victims, > injured USGS seismic hazard map prior to the earthquake

26 Probing the predictions of hazard maps Hazard map before GSHAP, 1999 Stein et al., Port-Au-Prince (Haiti) M = victims, > buildings destroyed and after.

27 Probing the predictions of hazard maps 2003 Boumardés M = 6.8, victims Stein et al., Marocco M = 6.4, 600 victims, displaced

28 2001 Gujarat, India, M = Bam, Iran, M = Boumerdés, Algeria, M = Wenchuan, China, M = 7.9 ASAMPSA_E Technical Workshop, September 2014 / Page 28

29 Are earthquake probabilities predictable? Yes, but many earthquake hazard maps do a bad job; and

30 Earthquakes on the North Anatolian Fault Izmit, 6. August 1999, M = victims, injured

31 The conditional probability of an earthquake on the North Anatolian Fault next to Instanbul

32 M = 7.4 Izmit (Turky), 6. August 1999 M = 7.4 Izmit (Turky), 6. August 1999 M = 7.4 Izmit (Turky), 6. August 1999 M = 7.4 Izmit (Turky), 6. August 1999

33 The conditional probability of an earthquake on the North Anatolian Fault next to Instanbul

34 The conditional probability of an earthquake on the North Anatolian Fault next to Instanbul

35 Magnitude or intensity what is useful for planning rescue missions? Earthquake Magnitude M = log 10 A/T + F(D,h) + C

36 Earthquake Intensity EMS-98 European Macroseismic Scale Grünthal et al., 1998 I - VI VII VIII IX X XI XII No (serious) damage Damaging Heavily damaging Destructive Very destructive Devastating Completely devastating

37 Vulnerabilty classes Damage grade A Adobe, earth bricks 1 B Unreinforced, no RC floors 2 C D Unreinforced, RC floors Reinforced 3 4 5

38 Intensity VIII many few many few few Grünthal, 1998

39 Intensity IX many few many few many few Grünthal, 1998

40 Izmit (Turkey), 6. August 1999 M = victims

41 Kobe (Japan), 17. January 1995, M = victims

42 What type of measure of the strength of an eartquake ( magnitude, intensity ) is useful for planning rescue? X Earthquake intensity provides straightforward information on damage

43 Are earthquakes more frequent today than they were in the past? Introducing the Gutenberg-Richter frequency relation

44 Are earthquakes getting more frequent? Total losses and insured losses caused by natural desasters Münchner Rück Topics Geo 2016

45 Are earthquakes getting more frequent? Number of damaging natural desasters events Münchner Rück Topics Geo 2016

46 Are earthquakes getting more frequent? How frequent are earthquakes? Global CMT Catalogue Gutenberg-Richter magnitude-frequency relationship describing self-organized criticality

47 Are earthquakes getting more frequent? How frequent are earthquakes? Global CMT Catalogue Gutenberg-Richter magnitude-frequency relationship describing self-organized criticality

48 How frequent are earthquakes?

49 Are earthquakes more frequent today than they were in the past? No - losses and numbers of victims increase because more and more people and values are exposed to risk

50 Where to get real-time data for the planning and preparation of rescue missions? Some on-line sources

51 Sources for real-time information European-Mediterranean Seismological Centre (EMSC) U.S. Geological Survey Last 24 hours before yesterday Last 24 hours before yesterday

52 (yesterday) ShakeMaps provide near-real-time maps of shaking intensity. The maps are used by federal, state, and local organizations, for postearthquake response and recovery, as well as for preparedness exercises and disaster planning.

53 (yesterday)

54 ShakeMap for 1999 Izmit M = 7.4

55 Izmit region on Google Earth

56

57 The short sumary of a short story Earthquakes are caused by tectonic faults Earthquake physics are too complex for predictions but they prove that earthquakes do not get more frequent Hazard maps provide information on earthquake probability However, hazard maps frequently fail Earthquake intensity is most meaningful for desaster mitigation Real-time information found in ShakeMaps