Effects of the 1995-1996 Ruapehu eruptions and people's perceptions of volcanic hazards after the event.

The Australasian Journal of Disaster
and Trauma Studies
ISSN:  1174-4707
Volume : 2001-1

Effects of the 1995-1996 Ruapehu eruptions on communities in central North Island, New Zealand, and people's perceptions of volcanic hazards after the event.

Julia Becker (1*), Richard Smith (1), David Johnston (2) & Adam Munro (3)

(1) Department of Earth Sciences, The University of Waikato, Hamilton, New Zealand
(*) now at IGNS, Wairakei Research Centre, Private Bag 2000, Taupo, New Zealand
(2) IGNS, Wairakei Research Centre, Private Bag 2000, Taupo, New Zealand
(3) Environment Waikato, Hamilton, New Zealand
(*) now HazardLink Consultants, 1906, 241 5th Ave N, Saskatoon, SK, S7K 2P3, Canada

Abstract

The 1995-1996 Mount Ruapehu eruptions provided an excellent opportunity to study the physical, social and economic impacts of a small volcanic eruption on New Zealand communities. In response, a questionnaire was designed and sent out to a number of locations in the North Island to collect information on peoples' post-eruptive perceptions of volcanic hazards, the impact of the eruptions on communities and individuals' responses to the eruptions. In addition, the survey placed a special focus on the effect the eruptions had on businesses. A number of respondents that answered the survey were directly affected by the Ruapehu eruptions, and had developed a heightened awareness of the type of hazards posed by an erupting volcano such as Ruapehu. This heightened awareness has implications for hazard education as direct experience of the 1995-96 eruptions may make subsequent warnings and information releases regarding volcanic hazards more salient, therefore encouraging individuals to respond in an appropriate way. Physical damage and disruption caused by the eruptions was minor and results from the questionnaire could be correlated with damage reported in other Ruapehu eruption studies. Individual responses to the eruption varied, with most reporting some degree of self-reliance in coping with the effects of the eruption. In dealing with ash falls, some individuals' actions were not consistent with recommended ash mitigation strategies and this may have been a consequence of incorrect advice, inadequate access to information, inappropriate interpretation of information or preconceived ideas. To eliminate as much error as possible in the future, it is essential that timely, accurate and clear hazard and mitigation information be disseminated both during and prior to an event.

Effects of the 1995-1996 Ruapehu eruptions on communities in central North Island, New Zealand, and people's perceptions of volcanic hazards after the event.

Introduction

During September and October of 1995, a series of ash-producing eruptions occurred at Mt Ruapehu. Activity resumed in June and July of 1996 with a further series of explosive eruptions. Lahars accompanied the eruptions with at least 36 occuring in the Whangaehu Valley alone by 14 August 1996 (Houghton et al., 1996).

The ash produced by the activity closed airports, caused damage to hydroelectric power facilities, and closed State Highway 1 (Johnston et al., 2000). Animal deaths occurred as a result of ash ingestion and fluorosis poisoning (Shanks, 1997), and fish in local rivers were affected by lahars. The ski seasons in 1995 and 1996 were disrupted by the eruptions causing financial loss for ski operators, and general tourist numbers were also down. Ash was a nuisance, and had to be cleaned up by both residents and business owners (Keys, 1996).

The 1995-1996 Ruapehu eruptions had some positive side effects. A new form of tourism emerged with the chance to observe an active volcano. The ash also acted as a fertiliser for pasture because it contained useful amounts of sulphur, minor amounts of selenium, and in some areas potassium and magnesium (Cronin, 1996; Cronin et al., 1996; Cronin et al., 1998). Another positive side effect was that the Ruapehu eruptions provided local experience in the management of small volcanic eruptions (Keys, 1996; Paton et al., 1998).

This study was initiated to further investigate the effects of the 1995-1996 Ruapehu ash falls on a number of communities located in the central North Island, New Zealand. In addition to the physical effects of the ash, other important issues were covered in the study including individuals' perceptions of volcanic hazards after the eruption had occurred, reactions of the community to ash falls and the response of individual community members.

A number of studies have been undertaken with regards to community perceptions and understanding of volcanic hazards and risk after volcanic crises have occurred (for example, Kartez, 1982; Saarinen and Sell, 1985; Yoshii, 1992). For the 1995 Ruapehu eruptions Johnston (1997a; et al., 1999) completed community perception studies of two towns (Hastings and Whakatane) both before and after the event. This enabled changes in perceptions of the two communities as a result of the volcanic eruption to be identified. Johnston (1997a; et al. 1999) found that communities' threat knowledge and risk perception appeared to be enhanced after experiencing the direct effects of the eruption. This heightened awareness has implications for hazard education, as information released to the community during this time may be more salient and may encourage the community to respond appropriately. Despite community threat knowledge and risk perception being enhanced by the eruptions, there appeared to be no increase in the preparatory activities of individual community members. They attributed this to a 'normalisation bias' where individuals were able to cope with the effects of the eruption and therefore assumed a future event would bring similar conditions that they would again be able to cope with. As this study was concerned with community perceptions of volcanic hazards after the 1995-1996 eruptions it was anticipated that a similar effect might be evident from the communities studied here.

Disasters and adversity are capable of provoking personal, community and professional growth and development (Bravo et al., 1990; Holman and Silver, 1998; Kreps, 1984; Schneiderman, 1996; Schwarzer, 1996; Schwarzer et al., 1994; in Paton, 2000). This growth and development contributes to a community's resilience, or the ability of a community to 'bounce back' after a disaster and recover using its own resources (Paton, 2000). A number of variables have been identified as elements useful in predicting resilience in community members and include 'sense of community', 'coping style', 'self efficacy' and 'social support' (Bachrach & Zautra, 1985; Bishop et al., in press; Miller et al., 1999). As this study, is in part concerned with the reactions of the community to ash falls and the response/coping styles of individual community members, there are elements of community resilience that have relevance to the study.

Method

For the study, a questionnaire was constructed in order to gain a post-eruptive perspective of peoples' perception of volcanic hazards, analyse the physical, social and economic impacts of the eruption and find out how community members responded.

The questionnaire was comprised of 27 questions separated into seven different sections. The first section contained questions designed to analyse peoples' post-eruptive perceptions of volcanic hazards. The subsequent sections of the survey contained a number of questions about the physical, economic and social effects of the eruptions on community members, and how individuals coped with the effects they encountered. These sections were entitled "The 1995 and 1996 Mt. Ruapehu Eruptions", "Effects of the Eruptions", "General Lifestyle and Health", "Benefits Arising from the 1995/96 Ruapehu Eruptions" and "Information and Assistance from other Organisations". A section was also included at the end of the questionnaire for respondents to provide comments on eruption issues that they thought were important. Questions were selected to on the basis for comparison with other research completed on the same issues (for example, physical impacts of Ruapehu volcano – Johnston et al., 1999; self reported stress - Ronan, 1997; Miller et al., 1999).

The majority of questions in the survey prompted participants to choose an answer from a range of suggestions. A number of questions also allowed participants to make a free response, so a full range of the effects of the eruption could be collected.

In order to study the effects of the Ruapehu eruptions on a variety of communities, a number of target communities both close to and far away from Ruapehu volcano were selected to send questionnaires to. These communities included Whakapapa Village, National Park, Turangi, Tokaanu, Taupo, Rotorua, Tauranga/Mt Maunganui, and Hamilton (Figure 1). A total of 489 businesses and homes from these communities were randomly chosen from the Business Directory and household Telephone Book, and the questionnaire was sent out in April 1998, approximately eighteen months after the 1995-96 eruptions had ceased. None of the communities targeted for this survey suffered any other significant hazard effects in the months following the Ruapehu eruptions. A total of 208 respondents completed the questionnaire, i.e. a response rate of 42.5%.

Both the multi-choice and a number of free response questions in the questionnaire were coded and entered into tabular format before undergoing statistical analysis. A few free response questions (for example, questions relating to the physical impacts of the eruption) and the comments section at the end of the questionnaire were not coded, and those responses were instead summarised.

Questionnaire Results

The results of the questionnaire follow, and are broken up into thirteen sub-headings that follow the format of the survey.

General Details

The effects of the eruptions on small businesses in particular had not been extensively studied after the Ruapehu eruptions, therefore, more businesses were randomly chosen to send the questionnaire to than residential homes.

The results indicate that 96% of respondents answered the questionnaire on behalf of a business. The other 4% answered the survey questions with regard to their home location. The businesses that responded were involved in tourism (27%), the service industry (26%), retail industry (15%), transport industry (9%), farming (6%) and professional occupations (6%). Smaller numbers of responses came from businesses involved with horticulture, trades, education, communication, research, industrial/manufacturing and health (3% or less for each category).

The abundance of responses from fields related to travel, tourism and the service industry reflects the predominance of these industries in the Ruapehu area and the vulnerability of those sectors to volcanic activity.

People were asked to place a cross on the map supplied with the survey to indicate where their business or home was located. During collation of responses, the map was subsequently divided into circular zones for the grouping of respondent locations, with each zone representing a particular radius around Mount Ruapehu. The first zone was from 0 to 20 kilometres around the mountain. The following zones (zones 2 through 8) were drawn at intervals of 30 kilometres (Figure 1).

Figure 1 The arrangement of zones around Mount Ruapehu.

The greatest number of responses to the survey came from the zones closest to the mountain. Zone 1 accounted for 8% of the total responses, zone 2 accounted for 31% of the total responses and zone 3 accounted for 13% of the total responses. Zone 5 also had an excellent number of responses (26%) and most of these responses came from an area northwest to northeast of the mountain area. In zone 7 the responses tended to be split between the two urban areas of Hamilton and Tauranga/Mt Maunganui. Zones 4, 6 and 8 only had limited responses to the survey and so the results obtained for the perception section for these zones may not be representative of the population.

Perception of Volcanic Hazards after the Ruapehu Eruptions

Over 50% of participants considered it 'extremely likely' that a future eruption from any volcano in the North Island would affect them. This high figure is probably a reflection of the fact that 81% of people that responded to the survey had been affected by the 1995/96 Mount Ruapehu activity in some way. It is likely that the perception of the respondents had been influenced by the recent eruptions.

The closer to Mount Ruapehu that respondents were located, the more people believed that they were extremely likely to be affected by a volcanic eruption occurring anywhere in the North Island. In zones 1 and 2, 76% and 66% of respondents respectively thought that it was extremely likely that they would be affected by a future volcanic eruption. This percentage generally decreased in zones further away from Mount Ruapehu (zone 3 (56%), zone 4 (25%), zone 5 (51%), zone 6 (18%), zone 7 (17%) and zone 8 (33%)).

For questions 8, 9 and 10, a list of possible volcanic materials that could be erupted by different types of volcanoes, or a resulting hazard was supplied (for example, ash, ballistic fallout, tsunami, etc). A short definition of each volcanic material or hazard was written alongside. Respondents could choose any number of hazards on the list that they thought would impact their community in a future eruption. In general, more 'familiar' volcanic materials or hazards, such as ash falls and lahars (experienced during the Ruapehu eruptions) were chosen more often than 'unfamiliar' hazards which occur less frequently.

Question 11 addressed whether or not people knew what to do if a particular hazard was to occur (for example, if ash fell on crops, or a pyroclastic flow were to occur, etc). The results indicate that for hazards that are unfamiliar (e.g. lava flows and pyroclastic flows) people were unsure of the impacts and how to respond. People were also ill-informed about hazards that didn't concern them directly, for example, a respondent involved in the ski industry may not know the appropriate action to take if ash fell on crops.

Volcanic Hazard Perception Results from other Surveys

Johnston (1997a; et al., 1999) undertook two surveys, one before and one after the 1995 Ruapehu eruption. This study collected information on peoples' perceptions of volcanic hazards in two towns (Hastings and Whakatane), before and after the 1995 eruption and identified the changes that occurred. It was found that respondents that had been directly affected by the eruption had gained a heightened awareness, meaning that subsequent warnings and information releases would be potentially more salient, and the likelihood of the individual responding would be enhanced.

This survey revealed trends similar to those found in the work undertaken by Johnston (1997a; et al., 1999), i.e. respondents that were affected by the 1995-1996 Ruapehu eruptions had a heightened awareness of future volcanic eruptions. This is reflected in the proportions of respondents who thought it extremely likely that a future eruption from a North Island volcano would affect them. Of the respondents who selected 'extremely likely', 87% had been affected by the 1995-96 Ruapehu eruptions, while 13% had not (Table 1). In contrast, of the respondents who considered that it was 'not likely' that they would be affected by a future eruption, 50% had been impacted during the 1995-96 eruption sequence while 50% had escaped the effects.

Table 1. Respondents' perceived likelihood of being affected by a future volcanic eruption from a North Island volcano and the proportions of people that had, and had not been affected by Ruapehu 1995-96.

We can divide the set of people affected by the Ruapehu eruptions into two subsets: those who were directly affected by ash from the eruptions (84%) and those who were not (16%). Table 2 shows the proportions of people directly and not directly affected by ash, and how likely they thought they would be affected by a future eruption.

Table 2. Respondents' perceived likelihood of being affected by a future volcanic eruption from a North Island volcano and the proportions of people that had, and had not been directly affected by ash from Ruapehu 1995-96.

Those respondents that had been directly affected by ash falls were more likely to believe that they would be affected by a future eruption. For example, 58% of respondents who had been affected by ash during Ruapehu 1995-96 thought it was extremely likely that they would be impacted by a future eruption. In contrast, only 48% of those not directly impacted by the ash falls believed it was extremely likely. These results indicate that those who had been directly affected by ash falls during the eruptions gained a more of a heightened awareness than people who had not encountered ash directly but had been impacted in other ways.

How Respondents were first Alerted to the Eruptions

Most respondents first became aware of the 1995 Mt Ruapehu eruption when they saw, heard or experienced the eruption first hand (Table 3). Of these people, most said they saw the ash cloud approaching. The second and third most common methods of finding out that an eruption had occurred was via the radio, and then by word of mouth. Many participants also pointed out that after they saw the ash cloud they turned on the radio to find out more information.

Table 3. The way respondents first learned there was an eruption occurring from Mount Ruapehu.

Short of seeing an ash cloud approaching, the radio will be one of the first sources to disseminate information in the event of a future volcanic eruption. It will continue to be a major source of information for people as the eruption continues. It is essential therefore that information broadcast from a radio station is up-to-date, accurate and is not contradictory.

Effects of the 1995-1996 Ruapehu Eruptions

After a hazard event has occurred, it is important that information about the physical, social and economic effects of the event is collected. Collected information can be useful in preparing for a future event of the same or similar nature and can provide input into reduction, readiness, response and recovery initiatives. For example, information on mitigation measures used for volcanic ash in the 1995-96 Ruapehu eruptions will be of use in planning ash mitigation strategies for future eruptions. Information on volcanic hazard consequences can be incorporated into hazard education programmes and thus be of assistance in community preparedness.

The following table (Table 4) summarises common physical impacts that respondents reportedly encountered as a result of the Ruapehu eruptions, and the range of individuals' responses to the problems. Most of the damage or disruption encountered during and after the eruptions could be attributed to problems associated with falling ash.

The results from this survey largely correspond with reports of damage or disruption in other studies of the 1995-1996 Ruapehu eruptions (Johnston et al., 1996; Johnston, 1997a; Treblico, 1997; Johnston et al., 2000). Research on volcanic eruptions overseas have also shown that similar effects have occurred, for example, Mount St. Helens in the United States, 1980 (Federal Emergency Management Agency, 1984; Johnston, 1997b), Mount Pinatubo in the Phillipines, 1991 (Spence et al., 1996) and Mount Spurr in Alaska, 1992 (Johnston, 1997b).

Table 4. Physical impacts of the 1995-96 Ruapehu eruptions, and common responses by community members.

Out of the respondents that were directly affected by ash falls (140 in total), 34% did not respond in any way, 31% responded with one action, 14% responded with two actions and 21% responded with three or more actions (Table 5). In contrast, those that were not directly affected by ash falls but were impacted in some other way either did not respond or undertook fewer actions. Eighty one percent of those who did not experience ash falls had no response, 15% responded with one action, 4% responded with two actions and no one responded with three or more actions. Respondents who were not affected by the eruptions did not respond in any way.

Table 5. Proportions of people that had, and had not been affected by ash falls during Ruapehu 1995-96 and people's active response to the eruptions.

People's responses varied depending on whether they had been directly affected by ash falls or not. The main response from those who were affected by ash falls was to undertake an ash clean-up. Those not directly affected by ash but who were impacted in other ways responded by changing recreational activities, travel plans, and work plans.

Financial Losses

Financial losses incurred by the businesses surveyed, typically amounted to less than NZ$10,000 (Figure 2).

Six types of business (51 in total) did not suffer any economic loss. Those businesses included veterinary services, forestry, panelbeating, information services, roading and plumbing. In fact, many of the businesses involved in the service industry, such as panelbeaters, plumbers and veterinary practices, experienced an increase in turnover because their services were in demand to deal with the effects of the eruption.

Figure 2 Economic loss respondents suffered in relation to the Ruapehu eruptions.

Major losses were experienced by the ski industry, tourist industry, accommodation services, the retail sector and those involved in water related sports. Respondents that ran businesses involved with the ski industry quoted losses of between NZ$50,000 and NZ$6,000,000. Tourist operators claimed that they had experienced losses ranging from hundreds of dollars to NZ$3,000,000. Those respondents that ran businesses to do with accommodation, retail or water sports said that they suffered losses ranging from hundreds of dollars to NZ$1,000,000.

It is not possible to calculate a total financial loss for the Ruapehu eruptions from the losses reported by respondents to this survey as the sample size is inadequate, and the coverage of businesses in the survey is not comprehensive. However, an estimate of loss as a result of the Ruapehu eruptions has been calculated by Johnston et al. (2000). They calculate a minimum loss of just under NZ$130,000,000 from the New Zealand economy as a result of the eruptions. This figure accounts for losses to tourism, electricity production, central government, aviation, regional and district councils, agriculture and insurance companies.

Long Term or Short Term

Respondents were asked if they considered the damage or disruption they suffered to be long term or short term. 'Long term' and 'short term' were not defined in the original questionnaire but were left up to respondents to decide whether they felt the eruption was a mere inconvenience or whether it had more far-reaching impacts. Three-quarters of respondents considered the damage or disruption to be long term.

Assistance Required During the Eruption

Forty-one percent of participants needed to use equipment to respond to the eruption. Of these, about a quarter had difficulty in locating or getting hold of the equipment they required. Most had difficulty in procuring dust masks but other items that were mentioned as difficult to obtain included waterblasters, a high pressure pump, rain wear, polythene sheets, containers to store fresh water in, a hose and sweeper unit and a spouting scoop.

Sixty seven percent of respondents affected by Mount Ruapehu, said that they solved any problems they encountered during the eruptions by themselves. This has implications for community resilience. Problem focused coping (confronting the stressor or problem) is a mechanism for facilitating community resilience (Miller et al., 1999; Paton, 2000; Paton et al., 2000). Problem focused coping, and thus resilience, can be further enhanced by employing community development initiatives in association with hazard education programmes (Paton, 2000).

Of those that did need to turn to others for help, there was no particular organisation or person that was asked most often. Instead of turning to one information provider, those that asked for assistance tended to approach whoever could solve the particular problems that the respondent faced. For example, if a respondent's guttering and downpipes needed attention, then the local plumber (the expert on fixing that particular problem) was asked for assistance.

That so few community members were unable to identify major information providers to ask questions about assistance during the eruptions, suggests that in a future crisis there is a need to ensure that information providers are easily identifiable and accessible to the public, and that information disseminated is consistent, appropriate, adequate and timely.

A variety of organisations were contacted by survey respondents seeking general information on the Ruapehu 1995-96 eruptions (as opposed to advice on how to solve a particular problem) (Table 6). The local radio station was where most people turned to receive information. The Institute of Geological and Nuclear Sciences, District Councils, and the Department of Conservation also all fielded a number of inquiries from people who wanted information about Mount Ruapehu.

Table 6. Organisations that respondents turned to for advice or general information during the 1995-1996 Ruapehu eruptions.

Aside from the local radio station, few organisations were identified and contacted by respondents seeking general information about the Ruapehu eruptions. This, again, emphasises the need for information providers to be easily identifiable and accessible to the public.

Health Problems

A small percentage of respondents (17%) reported experiencing physical health problems caused directly from the products of the volcano. The two main health problems that were cited were eye irritations and breathing problems due to airborne ash. As a subset of breathing difficulties, a number of people also specified that they had either developed asthma or suffered an increase in its severity and occurrence. While these respondents felt that they had suffered from asthma as a result of the eruptions, more detailed studies have in fact shown that there was not any overall significant increase in symptoms among asthmatics in the North Island during the period of ash eruptions from Ruapehu (Bradshaw et al., 1997).

Other health problems attributed to the ash by survey respondents included skin rashes, development of coughs, sore throats and nausea.

Some 45% of participants felt that they or their families had suffered stress as a result of the 1995 -1996 Mount Ruapehu eruptions. The most common causes of stress were due to being uncertain about what was going to happen next, financial pressures, and a general lack of knowledge about volcanic eruptions. Other causes of stress were "bad information" that had been given to respondents, lack of assistance in regards to insurance assessments, longer work hours, the time and effort involved in cleaning up, and an uncertainty of the future. Detailed psychological studies of the response of individuals to the 1995-96 eruptive sequence (for example, Ronan, 1997; Miller et al., 1999) confirm that distress was reportedly felt by individuals exposed to the eruptions.

That respondents reportedly felt stress over information issues (being uncertain about what was going to happen next and feeling they had a lack of knowledge about volcanic eruptions) verifies that during the eruptions there was a gap between information available about the volcano and its accessibility to community members. Individuals involved in an event should receive information to help them understand the issues and assist them in regaining control. This information should address safety factors, physical needs, normal psychological effects of natural hazards, and simple coping skills (e.g. simple problem-solving skills, how and where to access information and agency based support, the rationale behind using social support networks) (Johnston and Ronan, 2000).

Lifestyle Adaptations

In response to the Mount Ruapehu eruptions, 33% of participants said that they made some lifestyle adaptations while 67% said they did not make any adaptations. Of those that did make lifestyle adaptations, there were a wide range of changes (Table 7) and some people made multiple adaptations.

Table 7. Lifestyle adaptations made in response to the Ruapehu eruptions.

Direct experience of ash fall by respondents during the Ruapehu eruptions influenced the type of lifestyle adaptations made (Table 8). Most of those that made adaptations were directly affected by ash fall. There were 61 lifestyle adaptations made by respondents who had been directly affected by ash fall. By far, the most common adaptation made by people was to increase their preparedness in some way (24 adaptations were reported by respondents, with some people undertaking multiple preparedness activities). Eight adaptations were made regarding people changing their daily living patterns, eight involved changing work patterns, seven involved people changing their form or location of recreational activity and smaller numbers of other adaptations were made.

In contrast, there were only five adaptations made by respondents who had not directly experienced ash fall. Three of those adaptations involved the respondent changing their location or form of recreational activity, while the others included undertaking actions to increase preparedness, tightening finances and changing work patterns.

Table 8. Number of lifestyle adaptations made in response to the 1995-1996 Ruapehu eruptions and whether the people who made them were directly affected by ash or not.

Research by Johnston et al., (1999) found that an increase of threat knowledge as a result of being directly affected by the 1995 Ruapehu eruptions led to a slight but not significant increase in preparedness in Hastings and Whakatane communities. While there are no figures available to measure preparedness before the eruptions for the communities involved in this study, it is evident that some changes in preparedness were made by respondents as a result of their raised awareness and knowledge after being directly effected by the eruptions. Thirteen percent of respondents who were directly affected by ash from the eruptions reported that they had increased their preparedness in some way.

In contrast, only 1% of people who had not been directly affected by ash falls undertook some preparatory activities. It is possible that those not directly affected by ash falls have been subject to 'normalisation bias' where based on their experience from Ruapehu 1995-96 they consider themselves exempt from any impacts of a future volcanic eruption, and therefore have not been involved with any new preparatory activities.

Benefits

The majority of respondents in this survey (62%) said that they did not perceive any benefits from the 1995 and 1996 Ruapehu eruptions, while 38% said that they did see some benefits. The range of benefits experienced is listed in Table 9.

Table 9. Range of perceived benefits from the Mount Ruapehu eruptions.

Comments

A page of the Ruapehu survey was provided for respondents to make any additional comments. Many used this to voice concerns and criticisms. The common themes are summarised here.

The Media
There were a great number of complaints concerning the media. Many thought that the media were negative, sensationalist and provided inaccurate information, and that overseas media had blown the event out of proportion. Respondents thought that this type of reporting discouraged visitors from coming to the affected area.

Volcanic Hazards
One respondent located at a distance from the erupting Mount Ruapehu, said that they used the live "Volcanocam" on the Internet, to predict if there would be any problems from Mount Ruapehu. If there were pictures of an erupting Mount Ruapehu broadcast over the Internet, then there was a possibility of ash reaching their location if the wind was blowing in the correct direction.

Corrosion from Acidic Ash Particles
A number of comments were made by respondents stating that corrosion problems were long lasting where ash had fallen on metal surfaces and not been removed.

Soak Pits
A few respondents noted that they had problems with ash collecting in their soak pits.

Management Issues
Some of the comments that respondents provided regarding management of the Ruapehu eruptions are summarised as follows.

• Some people thought that authorities were caught short and out of their depth.
• There was some discussion of Civil Defence's perceived inadequate management of the situation, and the lack of information available from them.
• Respondents stressed the need for continual, up-to-date information on the state of the roads, water supply, etc.
• There was a feeling that more resources were needed for scientists monitoring the volcanoes.
• One respondent suggested that where an impending eruption can be predicted, people should be forewarned so that businesses can prepare (for example, cut down on spending) before the event.
• It was suggested that the purchase of a mobile doppler radar would be useful for monitoring ash plumes.
• Another suggestion by one respondent was to put an extra page in the telephone directory stating what to do, and who to contact in a volcanic eruption.

Discussion and Conclusions

People's Perception of Volcanic Hazards

The perceptions of people who answered the survey were largely constructed from their recent experiences of the 1995-96 Ruapehu eruptions. Because problems associated with ash fallout were common during the 1995 and 1996 Ruapehu eruptions, many New Zealanders who were caught in the fallout are now familiar with how to cope with minor ash related problems. Most respondents had gained a heightened awareness of a number of volcanic hazards arising from andesitic eruptions, but knew less about unfamiliar hazards from rhyolitic or basaltic volcanoes. Those who had been directly affected by ash from Ruapehu also felt it was more likely a future volcanic eruption would affect them.

Other studies on the 1995 eruptions from Mount Ruapehu have revealed similar results. Johnston (1997a; et al., 1999) found that after the 1995 eruptions people gained a heightened awareness, with people's threat knowledge and risk perception enhanced. An increase in people's threat knowledge and risk perceptions as a result of an event has implications for hazard education. Awareness aroused as the result of a recent event may make information released more salient to the affected communities. As a result a community may be more prepared to respond accordingly and contribute to community preparedness. For this study it was found that an increase in preparedness was made by 13% of those that were directly affected by ash falls.

Research on people's perceptions and the Ruapehu eruptions by Johnston (1997a; Johnston et al., 1999) also suggests that people who lived close to Mount Ruapehu during the 1995-96 eruptions but did not encounter any negative effects, may have developed a belief that future eruptions will again not impact them ('normalisation bias'). This study cannot confirm that 'normalisation bias' exists in this instance but the low levels of those undertaking preparatory activities who hadn't been directly affected by ash falls suggests that it is possible that 'normalisation bias' may be present.

To create awareness amongst those who were not affected by the eruptions, and to fill the knowledge gap about volcanic hazards in general, on-going hazard education is required. Future eruptions will undoubtedly affect people who were spared any direct impacts from the 1995-1996 events, therefore hazard education can inform them of appropriate mitigative actions to take in the event of a future eruption.

The Impact of the Eruption on Communities

From the survey results, it is evident that the physical impacts of the 1995-1996 eruptions on communities involved only relatively minor damage and disruption. This was limited to buildings, machinery, vehicles, some utilities, farming and the transport industry. The results of this survey are consistent with other studies of impacted communities, which have reported similar effects from the 1995-1996 Ruapehu eruptions (for example, Johnston et al., 1996; Johnston, 1997a; Treblico, 1997; Johnston et al., 2000) and from overseas studies (for example, Mt. St. Helens, 1980 (Federal, Emergency Management Agency, 1984), Mt. Pinatubo, 1991 (Spence et al., 1996), and Mt. Spurr, 1992 (Johnston, 1997b)).

Mitigation Measures Employed by People

Mitigation measures used by respondents to counter the effects of ash were similar to those used in past eruptions overseas, but tailored to New Zealand's environment.

People had different ideas on how to cope with the same problem. For example, for the problem of ash getting into downpipes people had different suggestions on what to do. Some simply said to hose the downpipes out, some said to disconnect the down pipes immediately after an ash fall, some said to hose from the top of the downpipes and collect the ash at the bottom and some said to remove as much ash as possible before hosing down. However, while the solutions they devised worked for them, it may not have been the most appropriate method. For example, hosing out the downpipes without first redirecting ash away from stormwater drains may have worked in the short term, but it may have caused problems further down the line for wastewater systems.

Another important issue is that the Ruapehu eruptions may have inadvertently contributed to entrenchment of misperceptions of volcanic hazards and what constitutes the appropriate response during a volcanic eruption. An example of this is the problem of ash falling on a roof. Because the 1995-96 Ruapehu eruptions only produced a light ash fall on roof tops, many people dealt with the problem by washing the ash off the roof with water. In a heavier ash fall, this practice should be discouraged as water causes the weight of the ash to increase substantially which can result in roof collapse. Again it is important that community education is undertaken to broaden people's understanding of the range of volcanic hazards and scales of possible eruptive activity.

Inappropriate responses from individuals may be due to incorrect information being given to the public or to respondents' misinterpretation of the information. Any information released during or immediately after an event will be more salient to the public, and will encourage a response from community members. Therefore to ensure that the mitigation measures employed by the public in a future eruption are appropriate, it is essential that accurate and clear information is disseminated to the public during this time.

Risk Management - Recommendations for Businesses

Results and comments from the 1995-1996 Ruapehu survey indicate that many businesses were unprepared for a volcanic eruption. It is recommended that businesses take responsibility for preparing their own plan to deal with the effects of a future eruption.

Some suggestions for planning for disaster include:-

• Establish a communication network made up of people both in and out of the workplace.
• Be prepared for disasters of many kinds. Know what you are covered for under insurance.
• Protect critical records. Keep backups of computer files, and keep a copy of critical records in a secure place off-site.
• Consider employee safety.
• Identify an alternative business site that can be used following a disaster.
• Consider management succession in case employees are stranded or incapacitated.
• A disaster may strand employees at work. Ensure there are supplies at work and know how to turn off workplace utilities in a disaster.
• Depending on the type of business, there may even be an increased demand for goods or services after a disaster (Klimas, 1993; Arvizu, 1995; Barrier, 1998; Offer, 1998; Institute for Business & Home Safety, 1999).

In the future, it is inevitable that another volcanic eruption will occur somewhere in New Zealand. When it occurs, both businesses and individuals will be more resilient if they are prepared in advance.

Acknowledgements

The data for this study was collected by Julia Becker as part of a Master of Science thesis at the University of Waikato. We would like to thank the University of Waikato and Environment Waikato for their financial assistance during the course of the research. Thank you also to Roger Briggs, Dave Parkin, Michelle Malcolm and Wendy Boyce who provided input and suggestions at various stages of the study.

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