1. RECENT EARTHQUAKES. NEW ZEALAND
Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, USA
lecture by Walter Hays Uploading date: November 15, 2016
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2. M7.8 EARTHQUAKE STRIKES NEW ZEALAND November 13, 2016
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3. New Zealand is in the southwest Pacific Ocean astride the “ring of fire,” a distinct belt of volcanic and earthquake activity that surrounds the Pacific Ocean

4. LOCATION: ON THE PACIFIC “RING OF FIRE”

5. To the north of New Zealand and beneath the eastern North Island, the thin, dense, Pacific plate moves down beneath the thicker, lighter Indo-Australian plate in a process known as subduction (i.e., reverse faulting).

6. RING OF FIRE

7. CHRISTCHURCH IMPACTED, BUT NOT SEVERELY THIS TIME
The earthquake, which had a shallow focal depth (23 km), struck 86 km north-northeast of Christchurch just after midnight on November 13.

8. NUMEROUS AFTERSHOCKS; SOME LARGE AND DANGEROUS

9. A TSUNAMI WAS GENERATED
The earthquake generated a tsunami causing a runup of 1-2 meters in some locations.

10. ONLY 2 DEATHS, SO FAR

11. CHRISTCHURCH: 185 DEATHS IN 2010
Christchurch is still recovering from the powerful earthquake that struck much closer to the city in 2010, killing 185 and destroying much of the city.

12. M7.1 EARTHQUAKE STRIKES NEAR CHRISTCHURCH, NEW ZEALAND
A DEEP (33 KM) QUAKE LOCATED 50 KM FROM CHRISTCHURCH STRUCK AT 4:35 AM
SEPTEMBER 3, 2010

13. Within the South Island the plate margin is marked by the Alpine Fault and the plates rub past each other horizontally (i.e., strike-slip)

14. NEW ZEALAND’S SUBDUCTION ZONE AND ALPINE FAULT

15. About 20,000 earthquakes (most, but not all are small) are recorded in New Zealand every year as a result of its location in the Pacific Ring of Fire

16. SEISMICITY MAP: VICINITY OF CHRISTCHURCH

17. NEW ZEALAND’S CITIES

18. PROBABILISTIC GROUND SHAKING MAP (CHRISTCHURCH IN YELLOW)

19. The largest cities within this high risk zone are the nation's capital, Wellington, followed by Hastings then Napier; all of them have experienced damaging earthquakes.

20. NOTE: The central part of most cities is comprised mainly of old, vulnerable brick and unreinforced masonry buildings, which are highly susceptible to damage.

21. UNREINFORCED MASONRY, BRICK OR STONE
REINFORCED CONCRETE WITH UNREINFORCED WALLS
CONSTRUCTION MATERIALS HAVE DIFFERENT VULNERABILITIES TO GROUND SHAKING 35 30 25 20 15 10 5
MEAN DAMAGE RATIO, % OF REPLACEMENT VALUE
REINFORCED CONCRETE WITH REINFORCEDWALLS
STEEL FRAME
ALL METAL & WOOD FRAME V VI
VII
VIII IX
INTENSITY

22. EPICENTER: NEAR CHRISTCHURCH, NEW ZEALAND

23. In Christchurch, a city of 372,000, power and water services were knocked out, facades fell off buildings, homes businesses, and bridges were damaged by strong shaking, fires were ignited, and the Christchurch Airport was closed.

24. IMPACTS Numerous injuries, but no deaths, largely due to the 4:35 a. m
IMPACTS Numerous injuries, but no deaths, largely due to the 4:35 a.m. time of occurrence, NOT BECAUSE the buildings were resilient to the strong ground shaking

25. DAMAGE: BFORE (TOP) AND AFTER (BOTTOM)

26. TYPICAL DAMAGE: UNREINFORCED MASONRY BUILDINGS

27. DAMAGE: CHRISTCHURCH

28. DAMAGE TO CARS

29. DAMAGE: CHRISTCHURCH

30. POUNDING

31. FIRE

32. DAMAGE: CHRISTCHURCH

33. DAMAGE: CHRISTCHURCH

34. DAMAGE: MOTORWAY

35. LOCAL GROUND FAILURE

36. AFTERSHOCKS OF THE 3 SEPT 2010 QUAKE
Christchurch was hit by hundreds of aftershocks after the M7.1 earthquake of 3 September 2010, which exacerbated damage and added new injuries, but no new deaths.

37. THE TOLL: EXTENSIVE DAMAGE, BUT NO DEATHS
The earthquake (and its aftershocks) caused extensive damage to buildings and infrastructure, but no deaths.

38. ECONOMIC LOSS: ESTIMATED AT $1.5 billion.