THE UNCERTAINTIES IN ASSESSING THE IMPACT OF REGIONAL SEISMICITY AT THE WIL SITE Statement of Evidence by Jocelyn Karen Campbell
A CANTERBURY FAULTS coded by type
CHARACTERISTICS OF THRUST FAULTS IN CANTERBURY
COMPARISON OF OBSERVED AND PREDICTED SPECTRAL ACCELERATIONS Darfield and Christchurch Earthquakes at Christchurch Stations
Proposed revison of spectral shape factor standard current seismic consideration is not conservative for stiffer soils and over-conservative for soft soils Soil Class A Strong rock B Rock Spectral shape factor in NZS1170.5 C Shallow soil D Deep soil E Very soft soil Revised shape factor
VERTICAL PGA common occurrence of vertical PGA close to, or exceeding, horizontal values
PROBABALISTIC SEISMIC HAZARD MODEL
HORORATA FAULT DATABASE HISTORY Source T L km length D Deg dip Dd Azimuth dipdirection Sr mm/yr slip rate M magnitude RI Yrs Recurrence interval Map ID Stirling1998 Not included in database Stirling2007 r 40 50 340 0.5 ± 0.1 7.1 4,800 BH1 45 Yetton 2009 1 r 40 50 340 0.5 7.1 4 800 BH2 GNS 2012 7.2 >17,000? Litchfield 2013 Barrell 2013 2 Current online database r 50 310 0.5 ± 0.1 BH1 49 6 0.2 12,000± 8,040 RH 2 15 n.e.3 n.e.3 RH
HORORATA FAULT ZONE and active structures in the 2010 Darfield earthquake (shading added to highlight areas of uplift during Darfield earthquake)
ACTIVE PROCESSES ALONG THE SOUTHERN HORORATA FAULT DURING THE DARFIELD EARTHQUAKE B A Growth distributed into blind footwall splays capped by actively growing anticlines. B Superposition of thrust and intersecting oblique slip fault accentuates uplift and combined elastic strain release with strong vertical acceleration
Basement Structures Malvern Hills R. Jongens
NORTHERN END OF HORORATA FAULT profile on south side of Waimakariri River showing typical fault propagation fault fold pairs (Fig Cc) and possible options for Hororata Fault style. C simple break to surface wedge and roof thrust fault propagation fold Jamison (1993)
PROJECTION OF THE HORORATA FAULT ZONE NORTH OF THE WAIMAKARIRI RIVER superimposed on well contrained earthquake locations Sept. 2010 to Jan. 2012
TWO NEW FAULTS A A Darfield anticline broad rise east of township on SH73 may be over blind thrust or fault bend fold B B Eyre Fault Surface fault trace striking west north of West Eyreton. Analogue of Greendale Fault, reactivated inherited basement fault.
THRUST FAULT BENEATH BURNT HILL A B A LiDAR image of fault trace. View Hill Stream bed uplifted 3m C c M. Finnemore 2004 B Locality of MF2 seismic reflection line on Parish Road C Fault trace on seismic line dipping SW beneath Burnt Hill displacing base of gravels by approximately 125m
PROJECTION OF THE HORORATA FAULT ZONE NORTH OF THE WAIMAKARIRI RIVER superimposed on well contrained earthquake locations Sept. 2010 to Jan. 2012
Satellite InSAR changes in elevation Darfield earthquake POINTS TO NOTE Black profile east of Hororata F shows differential displacement into footwall Strong displacement to north side of river associated with oblique slip Darfield anticline Warping over hanging wall to Eyre F on (green and magenta lines)indicates nw thrust motion of hanging wall Azimuth displacement in centimetres Confirms continuity of fault zone to north side of river
STRUCTURES NORTH OF WIL POND SITE
The Springbank Structure The topography follows the anticline profile of the seismic reflectors below Springbank fault does not reach the surface
HISTORICAL FAULT DATABASE ENTRIES
HISTORICAL FAULT DATABASE ENTRIES
HISTORICAL FAULT DATABASE ENTRIES
POSSIBLE CORRELATION OF RANGE FRONT EARTHQUAKES WITH SHORELINE PROGRADATION CYCLES?
So when s the next big one? SEISMOLOGY We feed the geological data for the area, the computer produces a schematic topological overview designating high probability key points, then we stick the printout on the wall and Johnson here throws a dart at it.