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Canterbury Statistics Day 2012. 4 th September 2010 Earthquake 7.1 magnitude earthquake 40km south west of Christchurch Happened at 4.30am No loss of.

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Presentation on theme: "Canterbury Statistics Day 2012. 4 th September 2010 Earthquake 7.1 magnitude earthquake 40km south west of Christchurch Happened at 4.30am No loss of."— Presentation transcript:

1 Canterbury Statistics Day 2012

2 4 th September 2010 Earthquake 7.1 magnitude earthquake 40km south west of Christchurch Happened at 4.30am No loss of life Major building damage (unreinforced masonry buildings and chimneys) Major land damage (extensive liquefaction, particularly in East of Christchurch (near beaches and rivers)

3 Canterbury Statistics Day 2012 Earthquake Locations

4 Canterbury Statistics Day 2012 Times Series of Earthquake Magnitudes

5 Canterbury Statistics Day 2012 Building Damage

6 Canterbury Statistics Day 2012 Land damage

7 Canterbury Statistics Day 2012 Land damage

8 Canterbury Statistics Day 2012 Power, water & sewage damage

9 Canterbury Statistics Day 2012 Liquefaction

10 Canterbury Statistics Day 2012 Most Chimneys lost

11 Canterbury Statistics Day 2012 NZ Earthquake Commission (EQC) Set up by Act of Parliament (1993) Compulsory insurance component on all home policies Cover to 100,000 (+GST) – median house price in Private insurer covers excess over 100K cap 3 months to claim after an event Holds $5.6 billion reserves plus reinsurance for excess

12 Canterbury Statistics Day 2012 September Survey EQC approached me in December to help estimate their liability for houses (excluded land costs) Too many (180,000!) claims to cost Worst properties assessed first so biases in using this data All claims in the database (after the 90 day limit) Able to use the claim database as a sampling frame Sample unit = claim

13 Canterbury Statistics Day 2012 September Survey Stratified Canterbury into 15 zones 5 regional zones 10 Christchurch Zones Christchurch zones formed by clustering suburbs on damage and geographical proximity Sampling with probability proportional to size Some claims were duplicated

14 Canterbury Statistics Day 2012 Canterbury Zones

15 Canterbury Statistics Day 2012 Christchurch Zones

16 Canterbury Statistics Day 2012 Estimated EQC liability $2.86 billion Error estimates by bootstrapping 95% CI $2.52 – 3.16 billion 1.2% had duplicate claims 2.7% of claims declined Survey only half completed when February earthquake occurred

17 Canterbury Statistics Day February Earthquake 6.1 magnitude centred in Port Hills right by Christchurch Happened at mid day on Tuesday (many people in city centre) Extensive building damage Loss of life (180) Extensive liquefaction Worst in Hills and East and Central city (tall brick & stone buildings) Cliffs collapsed & many runaway boulders

18 Canterbury Statistics Day 2012 Central City badly damaged

19 Canterbury Statistics Day 2012 Most old stone buildings damaged

20 Canterbury Statistics Day 2012 People killed by falling masonry

21 Canterbury Statistics Day 2012 People killed by falling masonry

22 Canterbury Statistics Day 2012 Building Damage

23 Canterbury Statistics Day 2012 Modern Reinforced Buildings collapsed

24 Canterbury Statistics Day 2012 More extreme liquefaction

25 Canterbury Statistics Day 2012 Houses on hills severely shaken

26 Canterbury Statistics Day 2012 Cliffs collapsed

27 Canterbury Statistics Day 2012 February Earthquake Shake Intensity

28 Canterbury Statistics Day 2012 New Survey to assess February Based on rapid assessment database (not all claims in + multiple claims) House/property became the sampling unit Christchurch only Many errors in database (46 spellings of Rangiora!) Duplicated addresses (10%) and missing addresses (12%) Estimated number of houses in Christchurch as 186,000 using Council records

29 Canterbury Statistics Day 2012 Survey Design Doubly stratified survey 12 geographic zones, by 6 damage classes (None – Rebuild) Geographic zones by clustering suburbs using rapid assessment data Numbers in zones proportional to size Numbers in damage classes proportional to expected cost

30 Canterbury Statistics Day 2012 Expected Claim by Suburb

31 Canterbury Statistics Day Zones

32 Canterbury Statistics Day 2012 Survey Samples ZoneNoneMinorModerateSeriousSevereRebuildTotal River Hill NWCentral Beach Bays South North ECentral NCentral SWCentral NWest West Total

33 Canterbury Statistics Day 2012 Survey Results EQC Liability $6 Billion Other insurers liability $2.5 billion Total residential rebuild $8.5 billion 90% of households made a claim 2% households uninsured (mainly in wealthier suburbs!) 63% of damage occurred in February September estimates were consistent with previous survey 15% of properties over 100K damage 100,000 properties to be repaired by Fletchers

34 Canterbury Statistics Day 2012 Survey Results

35 Canterbury Statistics Day 2012 Varying patterns of damage

36 Canterbury Statistics Day 2012 May Court Case Insurers vs. EQC EQC now liable for $100,000 for each event Total Damage must be apportioned across all events Transferred $500 million of liability to EQC EQC $100KEQC $160KEQC $300K Pre-MayEQC estimateInsurer estimate

37 Canterbury Statistics Day 2012 June 13 Earthquake 6.1 magnitude earthquake Further damage & liquefaction (often to worst affected suburbs) Revisited all survey houses Estimated extra $420 million in EQC liability Only added another 5% to the bill

38 Canterbury Statistics Day 2012 Monitoring Estimates vs. ‘Actuals’

39 Canterbury Statistics Day 2012 Broken down by damage class Comet overestimating lightly damaged buildings and under estimating badly damaged buildings

40 Canterbury Statistics Day 2012 Reinsurer Survey Reinsurers wanted a estimate of their liability – apportionment very important for this Used EQC list of properties with claims Doubly stratified survey Same 12 geographic zones, by Land damage classes (NA,TC1,2,3, Red) Numbers in zones proportional to population size Oversampled in TC3 and Red Zones 4 Batches of 500 completed Reinsurers happy with ‘novel’ process

41 Canterbury Statistics Day 2012 Reinsurer Survey Results

42 Canterbury Statistics Day 2012 Number of Claims/Property

43 Canterbury Statistics Day 2012 Private Insurer Survey To obtain a bulk apportionment between EQC and private insurers on “over-cap” properties Took 9 months to get sampling frame! Triply stratified survey Insurer x geographic zones x Land damage class Numbers by insurer proportional to market share < 30 properties completed after 3 months!

44 Canterbury Statistics Day 2012 Summary Surveys give unbiased estimates and random sampling covers the whole population Sampling frames and stratification adapted to the situation Surveys a great way of testing a process Monitor the process from the start to obtain learning Doing samples by batches gives early but balanced results plus early stopping options


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