Christchurch, New Zealand, Earthquakes of 2010 and 2011, Lifeline Performance

This chapter describes the impact of the sequence of earthquakes that hit Christchurch, New Zealand, and surrounding communities in 2010 and 2011. Three large earthquakes and a smaller fourth one affected the lifelines, mainly due to liquefication resulting in settlements and lateral spreads, as well as from rock falls and landslides. Thousands of buildings were damaged. This chapter clarifies how the rest of the book is presented, with abbreviations, limitations, and use of measurement units.

This chapter focuses on the tectonic setting and geological conditions in New Zealand. New Zealand lies along the boundary of the Australian and Pacific Plates. In the South Island, much of the relative displacement between these plates is taken up by a right lateral strike-slip fault, the Alpine fault. New Zealand has thousands of small earthquakes each year. The actual fault that caused the Darfield earthquake of 2010 was previously unknown, and is now called the Greendale fault. The chapter shows the area along with instrumented ground recordings for the 2010 event. Liquefaction during the February 2011 earthquake caused extensive flooding and large volumes of sand to be ejected on the ground surface. Due to the much more intense levels of shaking in the February 22, 2011 event, there were many more rock falls in the Port Hills area, with large boulders falling/rolling into a variety of residential and commercial structures.

The risk of earthquake for Christchurch, New Zealand, especially its central business district, was long considered to be only moderate. However, this chapter explains what a difference a seismic code from the 1990s and the reality of the earthquakes two decades later meant to an active city. The chapter also makes note of a vulnerability assessment report that was written in 1997 that spoke to the dangers that could affect not only the central business district but the area surrounding Christchurch as well.

The electric power system serving the Christchurch area is provided by three companies: Transpower, Orion, and Mainpower. Transpower operates the high-voltage transmission system nationwide, with highest voltages in the Christchurch area of 220 kV. Both Transpower and Orion had implemented some seismic mitigation measures in the decade before the September 4, 2010 earthquake. These countermeasures, including reinforcement of unreinforced masonry substation (URM) buildings in combination with the relatively modest levels of ground shaking, resulted in relatively excellent performance by both power companies in the September 4, 2010 earthquake. The February 22, 2011 earthquake had modest impact to the Transpower system: the Bromley substation had liquefaction and some component damage, and one 66 kV tower suffered a rock fall through the tower, but the tower remained standing. The URM facility had been seismically upgraded for inertial loads before the earthquake, but the risk from earthquake-triggered rock falls had been accepted.

For both the September 4, 2010 and February 22, 2011 earthquake events in Christchurch, there were a variety of damage-points in the nodes and links of the telecommunication networks. However, in both earthquakes, the loss of offsite electric power and limited duration of emergency backup battery power dominated the post-earthquake performance of telecommunication services. Chorus maintains and builds the Telecom's local access network, which is made up of local telephone exchanges, cabinets, and copper and fiber cables. Since Telecom owns a vast network of cellular, landline, and emergency call services, Chorus had to handle many earthquake-related failures. This chapter describes the failures and impacts on the cellular network. Due to extensive damages to Christchurch Central Business District (CBD), the network traffic was shifted to the locations where the businesses were relocated. Vodafone technology staff quickly modified the network to meet these shifting demands.

In Christchurch, potable water systems were damaged and in each of the three earthquakes in 2010 and 2011. Much of the damage resulted from broken water pipes due to triggered liquefaction. Liquefaction also damaged some wells in Christchurch in 2010 and 2011 earthquakes. Landslides and road-fill slumps affected water pipes in the Port Hills area in the February 22, 2011 earthquake. This chapter highlights water pipe issues in neighboring Kaiapoi, which suffered liquefaction and water pipe damage only in the September 2010 event. Major portions of the Christchurch City Council (CCC) water system became depressurized very rapidly after the September 2010 earthquake. Asbestos cement (AC) pipe in the Waimakariri District Council (WDC) water systems sustained massive damage where exposed to 2 to 4 inches of settlement or 12 to 40 inches of lateral spreads. Some of the damage modes for the concrete tanks are Wall, and internal column damage.

The Christchurch City Council (CCC) operates the wastewater system for Christchurch, and the Waimakariri District Council (WDC) operates the wastewater systems for Kaiapoi and Rangiora. This chapter discusses the wastewater system performance in the September 4, 2010 earthquake and in the February 22, 2011 earthquake. While both earthquakes created a lot of damage to the wastewater systems, the February 22, 2011 event was far more catastrophic for many reasons. Liquefaction was far more extensive in the February 22, 2011 earthquake. The trickling filters and digesters were non-operational two months after the earthquake. High Biochemical Oxygen Demand (BOD) in the effluent through the limited settling action from the primary settling basins was being discharged into the aeration ponds. Damage to the sewer pipes and treatment plant has required about two-thirds of the raw sewage to be discharged directly into the rivers and estuaries.

This chapter focuses on liquid petroleum (LP) gas reticulated distribution system, which is the only natural gas pipe supply network in Christchurch. One of the risks identified as part of the post-earthquake recovery of the area was the potential for damage to gas meters due to demolition of buildings. Contact Energy performed a gas leakage survey after the September 4, 2010 earthquake. It was found that there were a number of valve pits where the surface of the road sustained permanent ground deformation relative to the buried valves. The chapter also shows the 160-mm pipeline conveying gas from the Burwood Landfill, which is owned by Christchurch City Council (CCC). Under the combined effects of the Darfield and Christchurch earthquakes and the June 13 aftershocks, there has been no damage observed in any of the medium density polyethylene (MDPE) gas mains and only one instance of damage in a service line.

The deep-water port of Christchurch is located at Lyttelton Harbor in the Banks Peninsula south of Christchurch. The main port consists of four wharves named the Cashin Quays 1, 2, 3 and 4; an oil/liquid fuels berth, a container yard and office building facilities. The oil berth is constructed adjacent to a hydraulic fill reclamation retained by a rock dyke, with a wharf constructed along the harbor. This chapter shows the time histories for a ground motion instrument located at the port on firm ground/rock site immediately north of the Quays. The earthquake damaged the coal conveyors, likely due to differential movement of the steel conveyor supports where they were supported on Quay 1 and on land. The chapter also shows a plan and cross-section with displacement vectors on the Cashin Quays (CQ). The Lyttelton Port Company has had a long-term need for additional land reclaimed from the sea.

This one-page chapter describes effects of the September 4, 2010, earthquake. The effects were significant, because this was the only commercial airport serving Christchurch, and the air traffic control facility contended with some structural damage.

The automobile road and bridge system serving the Christchurch area are owned and maintained by four separate organizations: NZTA, Christchurch City Council (CCC), Selwyn District Council (SDC), and Waimakariri District Council (WDC). This chapter examines the performance of the road and bridge network in the September 4, 2010 earthquake and in the February 22, 2011 earthquake. NZTA had $6 million in damage from the September 2010 event and $40 million in damage from the February 2011 event. The Ferrymead Road Bridge, built in 1967, is a continuous three-span concrete bridge spanning the Heathcoate River in the southeastern part of Christchurch. The Moorhouse Avenue Bridge suffered significant damage during the earthquake. The Fitzgerald Avenue Bridge consists of two parallel concrete bridges. The Horotane Valley Road overbridge was retrofitted with span tie-links and shear keys with seat width extension before the earthquake.

KiwiRail operates a heavy rail network and a limited passenger train system for the South Island. The main rail traffic in the Canterbury region is transport of dairy products. Coal is principally transported from the western side of the South Island to the Port of Lyttleton via the Midland Line. This chapter shows the buckled rails where the right lateral fault crossed the Midland Line, northwest of Rolleston. The Linwood maintenance facility building was red-tagged after the earthquake and the staff was relocated to the Middleton facility. As of the first week of April, three locomotives were still trapped at the Linwood facility because of the tagging. The water tank at the facility was also damaged. The two passenger lines operated by KiwiRail were primarily for tourism. Rockfalls in the Port Hills area led to closure of one of the two parallel rail lines that serviced the Port of Lyttelton.

After the main shock of the earthquakes that hit during September 4 through September 11, 2010, aftershocks were felt for days. During that time, fires broke out in eight locations across the area. This chapter discusses the need for close communication and coordination among emergency crews who are responsible for lifelines in an earthquake-affected city to estimate correctly what services will be needed.

A system of levees, known in New Zealand as stopbanks, was built to prevent Waimakariri River from flooding. Christchurch is within the flood zone, and flood can reach as far as downtown Christchurch. Flood protection includes about 100 km of stopbanks along this river. The stopbanks affected by the earthquake are in the area close to river mouth of Waimakariri River and the junctions of Kaiapoi River and Kairaki River. A survey reported by Riley Consultants indicated the following damage to stopbanks: 10 had severe damage, 4 had major damage, 11 had moderate damage, and 14 had minor damage. As of August 2011, LiDAR mapping showed that several areas along the Ashley River floodplain subsided by as much as 0.4 m. LiDAR mapping along the Halswell River showed a decrease in channel capacity, which could lead to increased flooding potential for short return periods.

In this one-page chapter, general observations are made about lifeline interdependence and how water systems, road networks, power distribution systems and more can be immediately affected in the aftermath of an earthquake.

This chapter provides an overview of Darfield Earthquake September 4, 2010 and Christchurch Earthquake February 22, 2011. Approximately 200,000 individual structures in the region were shaken at PGA greater than about PGA =0.05g. The building stock includes unreinforced masonry (URM), reinforced concrete, precast concrete, steel, and wood frame construction. Most damage was concentrated to the older building stock, structures built prior to 1935. After the 1931 Napier, New Zealand earthquake that killed 256 people, building codes were modified to include some level of earthquake protection. The URM buildings include several large, heritage buildings as well as many small commercial stores. The high-density, commercial areas of Christchurch include many multistory reinforced concrete and steel buildings-all designed for earthquakes. The chapter shows the effects of surface fault rupture through a wood frame house. It is estimated that about half the total rupture movement was taken up by the house.

Widespread collapses of storage racks in warehouses, including two regional food distribution centers, led to a concern that the food supply might be disrupted. To compensate for the lost storage, food shipments by truck and train were undertaken from the North Island down to Christchurch along the Highway 1 corridor along the east coast of South Island. The actual design basis used for the failed heavily loaded storage racks in Christchurch is uncertain, but the level of ground shaking at the locations with the failed racks was commonly about PGA = 0.15g to PGA = 0.35g. A more thorough investigation into the proper seismic design of storage racks is called for both in the United States and in New Zealand. Base isolation units using inverted pendulums were installed at Transpower's regional control center. Horizontal ground motions at this site were about PGA = 0.25g to 0.30g.

Debris and waste hinder both services restoration and recovery in a timely manner. It is not an easy problem to solve as the trash usually includes hazardous material that requires special disposal processes, otherwise the consequence will be detrimental to health and pollute the environment. The cleanup will cost more than disposing the hazardous material properly in the beginning. The February 22, 2011 earthquake impacted an area with a mix of old and modern structures. Human factors also affects the decisions how to carry out the disposal processes, including financial matters, particularly when insurance is involved. A policy was quickly established to provide guidance in managing the debris resulted from the February 2011 earthquake. A coordinated effort must be established to ensure a timely restoration of services and cleanup of impacted areas to rebuild and to return to normalcy. The major effort is recycling reusable materials.