Preliminary report on the Canterbury Earthquake South Island of New Zealand 21.02.2011, M 6.3 Kyriazis Pitilakis and the group of - Aristotle University Thessaloniki, Greece.
General 2
General 147 people have been confirmed dead and 50 not yet accounted for Center of city evacuated as aftershocks continue Phone network outage in many areas after the earthquake Vast areas where liquefaction took place 3
This earthquake was an aftershock of the September 2010 magnitude 7.0 earthquake, and one of hundreds of aftershocks Christchurch has experienced. However, unlike the September 2010 magnitude 7.0 earthquake, which struck early in the morning when streets were virtually empty, this earthquake struck just before 1 pm local time when the streets, shops and offices in Christchurch were full. source: 4
Christchurch is still rebuilding from the September 3, 2010 magnitude 7.0 earthquake that struck 45 km (30 miles) west of the city. That earthquake damaged hundreds of buildings in the city and caused an estimated $5 billion in damage. A strong aftershock in December further weakened buildings. The epicenter of the February 21, 2011 magnitude 6.3 earthquake was just 5 km (3 miles) from Christchurch. Because of proximity to the epicenter, ground shaking in Christchurch was much more severe for this latest earthquake than for the larger magnitude 7 event in September. source: 5
New Zealand Tectonics 6
Deep earthquakes the last ten years 7
Shallow earthquakes the last ten years 8
New Zealand tectonics 9
New Zealand tectonics 10
Seismological aspects 11
Earthquake Details Magnitude: 6.3 Date-Time: Monday, February 21, 2011 at 23:51:43 UTC Tuesday, February 22, 2011 at 12:51:43 PM at epicenter Location: 43.600 S, 172.710 E Depth: 5 km (3.1 miles) Region: SOUTH ISLAND OF NEW ZEALAND Distances : NEAR Christchurch, New Zealand 225 km (140 miles) SSE of Westport, New Zealand 305 km (190 miles) SSW of WELLINGTON, New Zealand 310 km (190 miles) NE of Dunedin, New Zealand Location Uncertainty : horizontal +/- 12.2 km (7.6 miles); depth +/- 0.6 km (0.4 miles) Parameters: Nph= 0, Dmin=0 km, Rmss=0.98 sec, Gp= 0, M-type="moment" magnitude from initial P wave (tsuboi method) (Mi/Mwp), Version=D Source : Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand source: http://www.usgs.gov/ 12
Tectonic Summary The February 21, 2011 South Island, New Zealand earthquake occurred as part of the aftershock sequence of the M 7.0 September 3, 2010 Darfield, NZ earthquake. It involved oblique-thrust faulting at the easternmost limit of previous aftershocks, and like the mainshock itself is broadly associated with regional plate boundary deformation as the Pacific and Australia plates interact in the central South Island, New Zealand. This latest shock is significantly closer to the main population center of Christchurch, NZ, than is the September 2010 mainshock, in the vicinity of several other moderate (M 4 to 5) sized aftershocks located east of the main rupture zone of the 2010 event. Since the September 3, 2010 mainshock, there have been approximately 6 M>=5.0 aftershocks in the Christchurch region. The February 21st earthquake represents the largest aftershock to date, more that half a magnitude unit larger than the previous largest aftershock. source: http://www.usgs.gov/ 13
Earthquake location maps source: http://www.usgs.gov/ 14
Earthquake location maps source: http://www.usgs.gov/ 15
Intensity source: http://www.usgs.gov/ 16
Instrumental Intensity map source: http://www.usgs.gov/ 17
Peak Ground Acceleration source: http://www.usgs.gov/ 18
Peak Ground Velocity source: http://www.usgs.gov/ 19
Uncertainty source: http://www.usgs.gov/ 20
Spectral Response 0.3 sec Period 1 sec Period source: http://www.usgs.gov/ 21
Media Maps Decorated Bare source: http://www.usgs.gov/ 22
Earthquake Shaking Alert Level 23
Historical seismicity 24
Seismic hazard map 25
Earthquake Density Maps Average number of Earthquakes per Year per 12,300 km 2, Magnitude 5 and Greater Shallow Earthquakes: Depth 0-70 km 26
Earthquake Density Maps Average number of Earthquakes per Year per 12,300 km 2, Magnitude 5 and Greater All Depths 27
USGS Centroid Moment Solution USGS CENTROID MOMENT TENSOR 11/02/21 23:52:02.79 Centroid: -43.566 172.733 Depth 10 No. of sta: 36 Moment Tensor; Scale 10**18 Nm Mrr= 1.11 Mtt= 0.58 Mpp=-1.69 Mrt= 0.20 Mrp=-0.40 Mtp=-1.23 Principal axes: T Val= 1.47 Plg=45 Azm= 28 N 0.78 44 198 P -2.25 5 293 Visual representation of the style of faulting (focal mechanism) derived from the estimated moment tensor. Shaded areas show quadrants of the focal sphere in which the P-wave firstmotions are away form the source, and unshaded areas show quadrants in which the P- wave first-motions are toward the source. Best Double Couple:Mo=1.9*10**18 NP1:Strike= 60 Dip=56 Slip= 148 NP2: 170 64 39 28
USGS WPhase Moment Tensor Solution USGS/WPHASE CENTROID MOMENT TENSOR 11/02/21 23:51:42.00 Centroid: -43.513 172.438 Depth 15 No. of sta: 17 Moment Tensor; Scale 10**19 Nm Mrr= 0.06 Mtt= 0.06 Mpp=-0.12 Mrt= 0.05 Mrp=-0.05 Mtp=-0.10 Principal axes: T Val= 1.20 Plg=16 Azm= 64 N = 0.67 54 311 P = -1.87 32 164 Visual representation of the style of faulting (focal mechanism) derived from the estimated moment tensor. Shaded areas show quadrants of the focal sphere in which the P-wave firstmotions are away form the source, and unshaded areas show quadrants in which the P- wave first-motions are toward the source. Best Double Couple:Mo=0.2*10**19 NP1:Strike= 64 Dip=59 Slip= 156 NP2: 166 70 33 29
Historic USGS Moment Tensor Solutions 30
Theoretical P-Wave Travel Times Predicted (theoretical) travel times, in minutes, of the compressional (P) wave from the earthquake location to points around the globe. The travel times are computed using the spherically-symmetric IASP91 reference earth velocity model. The heavy black lines shown are the approximate distances to the P- wave shadow zone (103 to 140 degrees). source: http://www.usgs.gov/ 31
Geotechnical Information 32
Geotechnical Information 33
Google Earth mapping service 2004 Christchurch city council evaluation of liquefaction potential hazard. (red maps high liquefaction potential) Christchurch faces an additional hazard of liquefaction that can result from earth shaking during an earthquake, and which occurred in significant portions of the city in the September, 2010 earthquake. source:
Strong Motion Records 35
Much higher PGA and PSA values than the previous earthquake (Sept. 2010, M=7.1) In a specific location (LPCC) the PHGA (T=0) is almost 1.0g! and the PHSA values at T=0.10-0.20 sec are of the order of 3.0g!!!
Recordings source: http://www.stuff.co.nz/the-press/ 37
Recordings 38
Recordings comparison with the September 2010 EQ The following data are preliminary ground motions at 5 locations in the area obtained from the Feb 22 M6.3 Ground motions are filtered with bandpass 50Hz and 0.05Hz The figure below shows the locations of the six ground motion records: CCCC: Christs College CHHC: Christchurch hospital LPCC: Lyttleton port SHLC: Shirley school SMTC: Styx Mill TPLC: Templeton Dr. Brendon Bradley source: http://db.nzsee.org.nz 39
Recordings comparison with the September 2010 EQ The acceleration time histories have three figures (first two are horiz, third vert) The spectra are geometric mean (i.e. the geometric average of the two horiz components) Dr. Brendon Bradley source: http://db.nzsee.org.nz 40
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 41
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 42
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 43
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 44
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 45
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 46
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 47
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 48
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 49
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 50
Recordings comparison with the September 2010 EQ Dr. Brendon Bradley source: http://db.nzsee.org.nz 51
Recordings comparison with the September 2010 EQ The figures illustrate the following: Because of short source to site distance, the shaking in CCCC, CHHC, LPCC, SHLC was stronger than from the Darfield Mainshock. This is particularly at short vibration periods which the majority of building stock are. The shaking at Styx mill (SMTC) was similar to the Darfield mainshock Because of the small magnitude (i.e. source size), the shaking intensity is very localized, i.e. at Templeton (TPLC) the shaking is lower than the mainshock. Dr. Brendon Bradley source: http://db.nzsee.org.nz 52
Structural damage 53
Earthquake topples Christchurch Cathedral's spire Earthquake topples Christchurch Cathedral's spire source: guardian.co.uk
Earthquake topples Christchurch Cathedral's spire source:http://www.nzherald.co.nz 55
Cracks on structural elements source: http://db.nzsee.org.nz 56
Cracks on structural elements source: http://db.nzsee.org.nz 57
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 58
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 59
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 60
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 61
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 62
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 63
Total collapse of a building source:http://www.nzherald.co.nz 64
Total collapse of a building source:http://www.nzherald.co.nz 65
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 66
Total collapse of a building source:http://www.nzherald.co.nz 67
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 68
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 69
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 70
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 71
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 72
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 73
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 74
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 75
Total collapse of a building source:http://www.nzherald.co.nz 76
Total collapse of a building source:http://www.nzherald.co.nz 77
Total collapse of a building source: http://www.stuff.co.nz/the-press/ 78
Total collapse of a building fire after the earthquake source:http://www.nzherald.co.nz 79
Collapses on a block of buildings source: http://www.stuff.co.nz/the-press/ 80
Total collapse of buildings in a region source:http://www.nzherald.co.nz 81
Total collapse of buildings in a region source:http://www.nzherald.co.nz 82
Collapse of non-structural elements source:http://www.nzherald.co.nz 83
Collapse of non-structural elements source:http://www.nzherald.co.nz 84
Collapse of a building source:http://www.nzherald.co.nz 85
Collapse of non-structural elements source: http://www.stuff.co.nz/the-press/ 86
Collapse of non-structural elements source: http://www.stuff.co.nz/the-press/ 87
Collapse of structural elements source: http://www.stuff.co.nz/the-press/ 88
Collapse of non-structural elements source:http://www.nzherald.co.nz 89
Collapse of non-structural elements source:http://www.nzherald.co.nz 90
Collapse of non-structural elements source:http://www.nzherald.co.nz 91
Collapse of structural elements source:http://www.nzherald.co.nz 92
Collapse of non-structural elements source:http://www.nzherald.co.nz 93
Collapse of non-structural elements source:http://www.nzherald.co.nz 94
Collapse of non-structural elements source: http://db.nzsee.org.nz 95
Collapse of non-structural elements source: http://db.nzsee.org.nz 96
Lifeline damages 97
Flood of an area after the earthquake source: http://www.stuff.co.nz/the-press/ 98
Flood of an area after the earthquake most probably due to massive Liquefaction and massive damages of the water system source:http://www.nzherald.co.nz 99
Flood of an area after the earthquake source:http://www.nzherald.co.nz 100
Damage related to ground failures 101
Landslide source: http://www.stuff.co.nz/the-press/ 102
source: http://www.stuff.co.nz/the-press/ 103
Liquefaction source: http://www.stuff.co.nz/the-press/ 104
Liquefaction 105
Liquefaction source:http://www.nzherald.co.nz 106
Liquefaction source: http://www.stuff.co.nz/the-press/ 107
Liquefaction source: http://db.nzsee.org.nz 108
Liquefaction source: http://db.nzsee.org.nz 109
Liquefaction source: http://db.nzsee.org.nz 110
Liquefaction source: http://db.nzsee.org.nz 111
Ground failure source: http://db.nzsee.org.nz 112
Ground failure source: http://db.nzsee.org.nz 113
Raptures source:http://www.nzherald.co.nz 114
Raptures source:http://www.nzherald.co.nz 115
Raptures source:http://www.nzherald.co.nz 116
Raptures source:http://www.nzherald.co.nz 117
Raptures source: http://www.stuff.co.nz/the-press/ 118