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Recent large earthquakes, including Haiti 2010, could they have been predicted ?

Recent large earthquakes, including Haiti 2010, could they have been predicted ?. J. Havskov jens@geo.uib.no. Earthquake faults which generate earthquakes. El Centro Fault, California 15 Oct.1979 (M=6.9). El Asnam Fault, Algeria 10 Oct.1980 (M=7.6). A ‘nice’ strike slip fault.

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Recent large earthquakes, including Haiti 2010, could they have been predicted ?

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  1. Recent large earthquakes, including Haiti 2010, could they have been predicted ? J. Havskov jens@geo.uib.no

  2. Earthquake faults which generate earthquakes El Centro Fault, California 15 Oct.1979 (M=6.9) El Asnam Fault, Algeria 10 Oct.1980 (M=7.6)

  3. A ‘nice’ strike slip fault Izmit earthquake, 1999, M = 7.4

  4. Earthquake deformation, San Andreas fault The two sides move and the rock is elastically deformed The rock break in a sudden motion and the deformed rock move back to its original position

  5. The earthquake phenomena

  6. Seismic waves

  7. Earthquake source For a small earthquake, the source can be considered an instantaneous rupture on a fault. For a large earthquake, the rupture starts in one end and propagates along the fault with the rupture velocity. Rupture starts here Rupture propagates in direction of arrow If the fault is 600 km long and the rupture velocity is 3 km/s, then the shaking will be felt for 200 sec. Or we can say the earthquake lasts 200 sec.

  8. Global seismicity Plate boundaries, earthquakes (yellow) and volcanoes (red)

  9. Plate tectonics The major plates. Red arrows show direction of movement

  10. Subduction

  11. Spreading From continental rifting to full scale sea-floor spreading and the development of mid-oceanic ridges.

  12. Iceland Mid Atlantic ridge going through Iceland. Triangles are volcanoes. Volcanic eruption on Iceland

  13. Strike slip fault San Andreas Fault represents the plate boundary between the Pacific Plate in the west and the North American Plate in the east.

  14. Magnitude definition The Richter magnitude is defined as being proportional to the logarithm of the peak amplitude Magnitude ~ logarithm (peak amplitude)

  15. Modern magnitude Magnitude is also proportional to the logarithm of the area of rupture Magnitude ~ logarithm (area of fault rupture surface)

  16. Fault rupture areas of large earthquakes (Okumura, 2011)

  17. Energy, magnitude and number of earthquakes One magnitude unit increase implies 32 times more energy

  18. Total energy release in shallow earthquakes

  19. Comparison of recent and historic earthquakes by energy release

  20. Deadliest earthquakes known in history 1976 July 27, Tangshan, China, 255 000 casualties (M=7.5) 2004 Dec 26, Off NW-Sumatra (tsunami) 225 000 casualties (M=9.0) 1780 Feb 28, Iran, 200 000 casualties (M=?) 1920 Dec 16, China, Gansu, 200 000 casualties (M=8.6) 1927 May 22, Tsinghai, China, 200 000 casualties (M=7.9) 1556 Jan 23, Senshi, China, 830 000 casualties (M=~8.0) 1923 Sept 1, Japan Kanto (Tokyo fire), 143 000 casualties (M=7.9) 1948 Oct 5, Ashgabat, Turkmenistan, 110 000 casualties (M=7.3)

  21. Earthquakes do not kill, buildings do ! Izmit earthquake 1999, M=7.4

  22. Long time prediction Seismic gaps Medium term prediction Fault creep measurements Potential short time precursors Seismicity patterns Foreshocks Electromagnetic fields Radon or hydrogen gas content of soil or ground water Water level in wells Animal behavior Seismic wave velocity change Total electron content (TEC) Problems Only some earthquakes have precursors Monitoring all would be extremely expensive Earthquake prediction

  23. History of M >8 earthquakes since 1900 Does one earthquake trigger another ? Ammon, 2010

  24. Earthquake cycle and seismic gaplong term prediction Earthquakes at the same place repeat with regular intervals, used for long time prediction

  25. Earthquake migrationlong term prediction North Anatolian Fault Zone – major earthquakes Gaps and migration Barka et. al. (2002)

  26. Earthquake probability Istanbul (Pulido et al., 2004) Department of Earth Science University of Bergen Seismic hazard – Istanbul • 35-70% probability of a M=7+ earthquake in the Marmara Sea within the next 30 years (Parsons, 2004) • Scenario based ground motion modelling estimates ground shaking level

  27. Fault creep • Measures the slow rate of movement on the • fault. • Where lots of fault creep occur there is a small • chance of a big earthquake. • Where little amounts of fault creep occur there • is a high chance of a big earthquake. • Requires a surface fault

  28. Radon precursor Change in radon content a few days before the earthquake

  29. Animal behavior Unusual animal behavior: • Hibernating animals leaving their underground nests • Animals refusing to go into pens • Animals seeking higher ground • Birds vacating the area • Deep water fish come closer to the surface

  30. Recording device for a bird When the bird jumps, it is counted with the couter to the left

  31. Bird prediction Bird jumping times per day 15 days before and after large earthquakes

  32. Total electron content (TEC)precursor • Analyzing data from the Japanese GPS network, an increase in the total electron content (TEC) was detected in the ionosphere above the earthquake region of the 2011 Japan earthquake beginning about 40 minutes before the quake. • The TEC enhancement reached about 8 percent above the background electron content. • It was first observed prior to the 1964 Alaska earthquake • TEC has only been used in recent years Heki, 2011

  33. Cause of TEC The precise mechanism is not clear, suggestions are: Geochemical processes in the dilatant phase of earthquake preparation such as radon ionization, causing long-living ion clusters in the lower atmosphere. Activation of highly mobile electronic charge carriers in rocks near the earth’s surface. Release of CO2 gas which could potentially destroy neutral clusters, resulting in the near ground layer becoming rich in ions. The resultant lower-atmosphere electric field follows geomagnetic field lines into the ionosphere leading to the noted anomalies.

  34. Bam earthquake, cloud observed Method • Before earthquake, rock is compressed and heated and cracks forms • Ground water enters the cracks • Vapor is generated, escaping to cold air and vaporizing to create a cloud • Cloud detected by satellite • Satellite image shows cloud emerging from fault AB on Dec 21, 2003 • Shou predicted (Dec 25) a 5.5 or larger earthquake within 60 days • Dec 26 a magnitude 6.6 earthquake took place (*)

  35. Bam earthquake, December 2003, M=6.6 The earthquake near the city of Bam caused 30 000 casualties and almost total destruction of this historic city.

  36. Earthquake Prediction example: Haicheng, China – 1975, only successful prediction Winter, 1975: Chinese officials ordered the evacuation of Haicheng (population about 1 million) because: ·      Over a period of months, changes in land elevation and ground water levels observed ·      Accounts of peculiar animal behavior ·      Increase in regional seismicity ·      Increase in local seismic activity triggered the evacuation warning. February 4, 1975: Magnitude 7.3 earthquake struck the region a few days after evacuation. ·      2,041 people died; 27,538 were injured. ·      It was estimated that the number of fatalities and injuries would have exceeded 150,000 if no earthquake prediction and evacuation had been made.

  37. However ·  July 28, 1976: A magnitude 7.6 earthquake struck the city of Tangshan, a city with approximately one million inhabitants, without warning. ·  None of the precursors observed near Haicheng were observed this time. 250,000 fatalities and 164,000 injured. - This shows how prediction is difficult if not impossible

  38. Some recent large earthquakes • Sumatra, December 26, 2004, M=9.0 • Haiti, January 12, 2010, M=7.0 • Chile, February 27, 2010. M=8.8 • Japan, March 11, 2011, M=9.0

  39. Sumatra earthquake, Dec 26, 2004, M=9.0 Subduction along the Sunda trench is the main source of significant earthquake activity in this region.

  40. Sumatra seismic gap In the region, there are at least six significant historical earthquakes that occurred prior to the 2004 event. • Event occurred in seismic gap • No short term changes in seismicity indicating a large earthquake • TEC anomaly observed 5 days before earthquake From CalTech (K. Sieh)

  41. TEC anomaly 5 days before Sumatra earthquake Liu 2011

  42. Tsunami generation Deformation accumulates The fault slips, the sea bottom moves up and generates a wave in the water The wave starts to propagate towards the ocean and towards the coast

  43. Tsunami wave

  44. Chile, February 27, 2010, M=8.8 >500 dead Seismic code followed, earthquake epicenter outside the coast, so relative few casualties

  45. Earthquake filled gap This earthquake filled the seismic-gap between the March 3, 1985 Valparaiso earthquake (MW =7.9) in the north and the great 1960 earthquake (MW =9.5) in the south.  Last big earthquake in this regions was in 1835, M=8.2, GPS measurements before the earthquake showed that the fault was locked. 2012 earthquake M=7.2

  46. The gap • No reported foreshocks • TEC anomaly seen, but was not checked before after the earthquake Lorito et al, 2011

  47. Caribbean seismicity . Important events from 1900 to present, from USGS

  48. Historical earthquakes before 1960 From Calais

  49. Seismic hazard

  50. Frankel et al., 2010

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