Aug 26 2008 - Moderate quake shakes Hawke's Bay
A magnitude 5.9 earthquake centred 10 km south-west of Hastings at a depth of 30 km shook Hawke's Bay on Monday night.
The focal mechanism of Monday night's mainshock.
Last update August 29, 4:00 pm
Mainshock details
Major aftershocks to date
Only a weak aftershock sequence is expected for this type of earthquake, not lasting for too many days and with few large aftershocks.
- Monday, August 25 at 11:35 pm, magnitude 3.5
- Wednesday, August 27 at 6:23 am, magnitude 3.4
- Thursday, August 28 at 10:29 am, magnitude 3.4
No tsunami
Due the earthquake's magnitude of 5.9 and its depth at 30 km, and as this earthquake occurred under the New Zealand landmass, there was no tsunami generated.
Reported damage
Reports of damage sent in through the online felt questionnaire are consistent with an estimated maximum Modified Mercalli Intensity of MM 7 in the Bay cities; one report of MM 8 has been received. In both Napier and Hastings we have reports of damaged chimneys, broken windows and some cracks in walls. Household contents have taken a battering with items falling from shelves and furniture being displaced. An office building in Taradale was not safe to enter until cleared by authorities later in the morning.
The earthquake was widely felt in the North Island from Waikato through to Wellington and weakly in the upper South Island.
Earthquake characteristics
The focal mechanism (see accompanying figure) is an almost pure normal faulting mechanism where one side of the fault slides downwards relative to the other side. The red area of the mechanism has moved downward relative to the white area. There are two possible choices for the fault plane; however, without additional information it is not possible to determine which the actual fault plane is. This type of faulting generally occurs in regions that are being stretched or pulled apart. The depth and the normal faulting mechanism are consistent with the earthquake being located within the Pacific Plate to the east as it pushes beneath the Australian Plate to the west and is pulled apart. A good description of fault plane solution representations (or beachballs) and the faulting type are to be found at the United States Geological Survey.
There has been no observable signal at GPS sites within the vicinity of Hastings, consistent with the moderate magnitude of the earthquake.
Similar past earthquakes
Since 1980, there have been two earthquakes causing similar levels of damage in Hawke's Bay:
