MUSEUM OF NATURE

Press, Volume CX, Issue 32460, 21 November 1970, Page 13

MUSEUM OF NATURE

Damaging earthquakes in Christchurch

(Contributed by the Canterbury Museum)

.. Christchurch has been damaged by earthquakes in the past, and damage will occur again. The intensity of an earthquake at a particular place is measured on the Modified Mercaili scale, intensity is not recorded by seismographs but is assigned by analysing the answer to such questions as “Was everybody woken up?” and “Did your clock stop?” Houses and buildings are not usually damaged until the intensity reaches MM VI to VII. The mountains and foothills of Canterbury bear the abundant scars of past earthquakes, but the first of which we have definite knowledge woke the Deans brothers from their sleep at Riccarton at 6 a.m. on August 16, 1844. It gave them a fright but did no damage and has been rated about MM IV. First records The first recorded damage by an earthquake in Christchurch was caused by a strong tremor at 8 a.m. on June 5, 1869. According to newspaper reports, chimneys fell in all directions. The Provincial Government Buildings, completed in 1865, were the most severely damaged and two chimneys were thrown down. The side of a small brick house between Madras and Manchester Streets was shaken out. In Lyttelton it was feared that the shock was a result of an accident in the railway tunnel which was then almost completed. Julius Haast, Director of the Canterbury Museum, appealed to the public for information about damage done by the earthquake. The intensity has been rated at about MM VII, and it may have been the strongest earthquake felt in Christchurch. In 1870, on August 31, an earthquake brought down a chimney in Chester Street and was about MM VI intensity. An earthquake on December 5, 1881, was the first to damage the spire of the newly consecrated Christchurch Cathedral. A stone was shaken out 14ft below the cross. A chimney and ceilings were damaged at the Normal School, and plaster was cracked at the Museum. The intensity was about MM VI. The next strong earthquake was on September 1, 1888, at 4.12 a.m., and originated near Glynn Wye on the Lewis Pass road. The top 26ft of die masonry spire of the Christchurch Cathedral gave way and the cross hung suspended by iron bands built into the stonework. At the Normal School, a chimney fell and the plaster ceilings were badly damaged. The museum escaped without damage, apart from a few small specimens being overturned. This was one of New Zealand’s major earthquakes, with a probable Richter magnitude of 7, and the intensity in Christchurch was about MM VII. After this 1888 earthquake, the Cathedral spire was rebuilt in brick, and Bishop Julius was winched to the top in a bosun’s chair to lay the coping stone. On December 27, 1888, and August 4, 1895, there were earthquakes of intensity about MM V to VI in Christchurch. The second shock brought down two chimneys. Cathedral damage The Cathedral spire was again damaged by the Cheviot earthquake of November 16, 1901. The top five feet of the spire was shifted bodily two inches to the south-east. This damage, together with that in 1888, is illustrated in a display on earthquakes in the Von Haast Hall of Geology at the Museum. Some chimneys were cracked but there was little damage to other build-

ings, and the intensity was about MM VI. The Cathedral spire was replaced in its present form of Australian hardwood sheathed in copper. On Christmas Day, 1922, at 3.03 p.m. an earthquake brought down many chimneys and some masonry fell from buildings, including that of "The Press.” The M.C.C. v. Canterbury cricket match at Lancaster Park was interrupted for three minutes. The intensity was MM VII and more damage was done at Rangiora. The Arthur’s Pass earthquake of March 9, 1929, was a major one with a Richter magnitude of 7. Chimneys fell in Christchurch and the

intensity was MM VI to VII. Later the same year, the Murchison earthquake of June 17 was felt all over New Zealand, and had a magnitude of 7J. Chimneys once more fell in Christchurch, the Cathedral bells were set ringing (as had happened in March), and the intensity was MM VI to VII. Our latest damaging earthquake, but certainly not the last, was the Inangahua earthquake which woke the people of Christchurch at 5.25 a.m. on May 24, 1968. The Richter magnitude was 7. A few weak chimneys were cracked and the intensity in Christchurch was about MM V.—D.R.G.