article: Feb 3 2005 - Lower North Island Events Generate Huge Interest

Last month's earthquakes in the lower North Island were of great public interest.

Within the most active week, the GeoNet web site received 6.7 million hits (of which 2.4 million were on the Friday after the largest event). This equates to around 600,000 page requests for the week (there are about 11 hits per page).

Traffic volumes saw 25.7 gigabytes served for the week, of which 9.4 gigabytes was on Friday - only a few megabytes below the previous day peak caused by the arrival of Dino on the White Island web camera back in May 2004.

The graph detailing the load patterns shows which events generated the most interest. Note also the effect of people arriving at work on Wednesday to catch up on events felt at home the previous evening.

The felt reporting questionnaire was unable to cope with the high demand, and we apologise to those who found this a frustrating exercise. We have since been able to move to improved hardware and software for this feature. The map of felt responses for the magnitude 5.5 Upper Hutt event is shown at the left. The epicentre of the earthquake is shown by the letter "E" in green relief. To date, 1148 reports have been received.

The Modified Mercalli (MM) shaking levels, the brief definition of their effects on people, and the localities that experienced them, are shown below. Where a number appears in square brackets [n], 'n' reports were received from that locality:

• MM 7 - "General alarm. Difficulty experienced in standing. Noticed by motorcar drivers who may stop":
  Maymorn, Normandale, Stokes Valley, Wellington.
  
  
• MM 6 - "Felt by all. People and animals alarmed. Many run outside. Difficulty experienced in walking steadily":
  Avalon [2], Crofton Downs, Fairfield, Gracefield, Hataitai [2], Johnsonville [2], Karori, Karori West, Kelburn, Linden, Lower Hutt [3], Lowry Bay, Lyall Bay, Maungaraki [2], Melrose, Mount Cook, Mount Victoria, Naenae, Newlands, Newtown [3], Ngaio, Paekakariki, Palmerston North, Paraparaumu [5], Paraparaumu Beach, Petone [2], Pinehaven, Porirua, Raumati Beach, Raumati South [2], Silverstream, Stokes Valley [4], Tawa [3], Te Marua, Timberlea, Totara Park, Trentham [3], Upper Hutt [9], Waikanae, Wainuiomata [13], Waiwhetu [3], Waterloo [2], Wellington [13], Whitemans Valley [2], Wingate.
  
  
• MM 5 - "Generally felt outside, and by almost everyone indoors. A few people alarmed":
  Akaroa, Alicetown, Avalon [4], Awapuni [2], Belmont [2], Berhampore, Birchville [2], Boulcott, Broadmeadows, Brooklyn [8], Brown Owl, Carterton [2], Churton Park, Eastbourne [3], Eketahuna, Elsdon, Epuni [3], Featherston [2], Feilding, Foxton, Foxton Beach, Gonville, Gracefield, Greytown [2], Hataitai [5], Hawera, Haywards, Heretaunga [2], Highbury [2], Himatangi Beach, Houghton Bay, Island Bay [6], Johnsonville [11], Judgeford, Karori [7], Karori West, Kelburn [12], Kelson, Khandallah [3], Kilbirnie, Kingston [2], Lower Hutt [24], Lowry Bay, Lyall Bay [2], Mana, Maoribank, Martinborough [2], Masterton [5], Maungaraki, Mauriceville West, Melrose, Miramar, Moera, Moiki, Mount Cook [4], Mount Victoria [6], Naenae [10], Nelson, New Plymouth [6], Newlands [8], Newtown [8], Ngaio [2], Northland [3], Otaki [2], Otaki Beach, Paekakariki [4], Palmerston North [8], Papakowhai [3], Paparangi, Paraparaumu [12], Paraparaumu Beach [7], Paremata, Pauatahanui, Peka Peka, Petone [13], Picton [3], Pinehaven, Plimmerton [3], Porirua [3], Porirua East [2], Port Nelson, Pukerua Bay [3], Raumati Beach [6], Raumati South [3], Rongotai, Roseneath, Roslyn, Seatoun Heights, Silverstream [5], Stokes Valley [16], Tawa [5], Timberlea [2], Titahi Bay [4], Totara Park [3], Trentham [9], Umutaoroa, Upper Hutt [17], Wadestown [3], Waikanae [6], Wainuiomata [11], Waiwhetu [3], Wallaceville [7], Wanganui, Waterloo [6], Wellington [109], Whangaehu, Whitby [8], Whitemans Valley [2], Wilton [3], Wingate, Woburn [2], York Bay.
  
  
• MM 4 - "Generally noticed indoors but not outside. Vibration may be likened to the passing of heavy traffic, or to the jolt of a heavy object falling or striking the building":
  Alicetown [4], Aokautere [2], Aramoho [3], Avalon [3], Awapuni [3], Awaroa Hut, Bastia Hill, Bell Block [3], Belmont, Berhampore [2], Birchville, Blenheim [2], Breaker Bay, Brooklyn [4], Bulls, Bunnythorpe, Camborne [3], Carterton, Churton Park [5], Cloverlea, Crofton Downs, Durie Hill, Eastbourne, Elsdon, Eltham, Endeavour Inlet [2], Epuni, Featherston [4], Feilding [3], Foxton [2], Foxton Beach, Gladstone, Gonville [2], Gracefield [2], Greytown, Hataitai [8], Havelock [2], Hawera [2], Heretaunga [3], Highbury [3], Houghton Bay, Island Bay [12], Johnsonville [4], Kaiwharawhara, Karori [11], Karori West [2], Kelburn [7], Kelson [3], Khandallah [7], Kilbirnie [5], Kingston, Korokoro, Levin [7], Linden, Longburn, Lower Hutt [14], Mana [3], Mangaroa [2], Maoribank, Marton [2], Masterton [6], Maungaraki, Melrose [5], Miramar [6], Mitchelltown, Moera [2], Mornington [3], Mount Cook, Mount Victoria [5], Naenae [2], Nelson, New Plymouth [6], Newlands [3], Newtown [10], Ngaio [8], Normandale, Northland [5], Ohakune, Otaki Beach, Pahiatua, Palliser Bay, Palmerston North [19], Papakowhai [3], Paraparaumu [5], Paraparaumu Beach [8], Paremata [5], Pauatahanui, Petone [4], Picton [8], Pinehaven [2], Plimmerton, Pomare, Porirua [5], Porirua East [2], Pukerua Bay [2], Raetihi, Raumati Beach [3], Raumati South, Raurimu, Riverstone Terraces [2], Rongotea, Roseneath [2], Roslyn, Sanson, Seatoun [2], Seatoun Heights, Seaward Hills, Shannon [2], Silverstream [8], South Taranaki Bight, Springvale [3], Stoke, Stokes Valley [8], Summerhill, Tahunanui, Taita, Tangimoana, Taumarunui, Tawa [12], Te Horo Beach, Te Marua [5], Terrace End [3], Timberlea, Titahi Bay [3], Totara Park [3], Trentham [2], Tuamarina, Upper Hutt [13], Vogeltown, Wadestown [3], Waikanae [8], Waikanae Beach [3], Wainuiomata [6], Waiwhetu, Wanganui [6], Wanganui East [2], Wellington [97], West End, Westown, Westport, Whitby [5], Woburn [4].
  
  
• MM 3 - "Felt indoors; hanging objects may swing, vibration similar to passing of light trucks, may not be recognised as an earthquake":
  Hillmorton, Motueka, National Park, New Plymouth, Ohakune, Turangi.

The South Karori (SNZO) seismic drum has been unavailable for viewing for a number of months. We have had difficulty restoring the communication link between our data centre in Lower Hutt and the South Karori site. The link had been getting progressively worse over a number of months before finally failing in mid-October 2004. The seismic and communications equipment is owned and supplied by IRIS, and we have been liaising with them to restore their real-time link. The data itself is still being collected on disk, and periodically sent to the IRIS data centre in the United States. A new digital link is to be established soon, and we are hopeful that the seismic drum will be available again by the end of February 2005.