Decription:

The report on the March 1987 Edgecumbe earthquake has been prepared by consulting engineers George Butcher and Latham Andrews and economist Graham Cleland, and is being partially funded by EQC. The report reviews the types of damage caused by the earthquake, the management of the recovery period, the estimated costs of reconstruction and the economic impacts of the earthquake on the region.

It is believed that the study of lessons to be learned from this earthquake is important because although it is now nearly ten years since it occurred, it is still the most recent earthquake to have caused major damage in New Zealand.

The earthquake of 2 March 1987 is known throughout the district it affected as the Eastern Bay of Plenty earthquake, and in scientific and engineering circles as the Edgecumbe earthquake. Although of modest magnitude, it generated more intensely felt shaking than has been experienced by any New Zealand community since the Inangahua (West Coast) earthquake in 1968.

The decade since it shook the Rangitaiki Plains has seen some of its warnings heeded, some lessons learned and some lessons ignored. Communities and their assets are marginally safer and better prepared to combat an earthquake's adverse effects than they were before this earthquake occurred, but more benefit could have been taken from analysis of the experience.

Stricken Edgecumbe, Te Teko and Kawerau are all comfortably close to, and were accessible from, Whakatane, the district's principal town (which was almost unscathed), and a source of immediate aid after the earthquake. This fortunate circumstance is rare in New Zealand's seismic experience; most areas devastated by our historically damaging earthquakes have been isolated by the events and have remained remote from effective help for lengthy periods.

The Edgecumbe earthquake was an ideal one for scientific study. Monitoring the region before the main shock occurred was the national array of seismographs, and a group of strong motion accelerographs was at Matahina dam on the Rangitaiki River.

At the time of the earthquake, the seismograph network was due for local augmentation by portable instruments, then in transit from Wellington, to gather improved information about the earthquake swarm occurring at the coast, retrospectively recognised as foreshock activity. The instruments were immediately deployed to record aftershocks.

Thus the data needs of geophysicists and engineering seismologists were satisfied. Surface traces of earthquake fault movement were prominent — they traversed open uncluttered country, much of it pastureland, and were easily accessible for study, recording and measuring, by geologists, soil scientists, surveyors and photographers.

Because New Zealand's earthquake insurance scheme provided for cover by a single insurer, the Earthquake and War Damage Commission (now the Earthquake Commission), for almost all properties, a reasonably consistent record of property losses was compiled at one location. These data, although imperfect in some respects, are probably better for statistical evaluation of damage than have been collected after a comparable event anywhere else in the world.

The report is more than simply an account of the record assembled of the scientific, engineering, administrative, economic, insurance and social consequences from a moderately intense earthquake in an area predominantly rural but containing several very large industries. Guidance and benefit should flow from the overview afforded by such a collection of reported fact and informed opinion. These are the book's primary purposes: to identify lessons, giving prominence to what has hitherto been overlooked, and to present a reliable picture of the earthquake, with misrepresentations eliminated, so that reliable conclusions can be drawn.