Emma E.H. Doyle

Submarine pyroclastic deposits formed at the Soufrière Hills volcano, Montserrat (1995–2003): What happens when pyroclastic flows enter the ocean?

The Soufriere Hills volcano, Montserrat, West Indies, has undergone a series of dome growth and collapse events since the eruption began in 1995. Over 90% of the pyroclastic material produced has been deposited into the ocean. Sampling of these submarine deposits reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the sea. The coarse components (pebbles to boulders) are deposited proximally from dense basal slurries to form steep-sided, near-linear ridges that intercalate to form a submarine fan. The finer ash-grade components are mixed into the overlying water column to form turbidity currents that flow over distances >30 km from the source. The total volume of pyroclastic material off the east coast of Montserrat exceeds 280 × 106 m3, with 65% deposited in proximal lobes and 35% deposited as distal turbidites.

Static and flowing regions in granular collapses down channels : Insights from a sedimenting shallow water model

A two layer model for the collapse and spreading of a granular column is presented. This model builds upon that of Larrieu et al. [J. Fluid Mech. 554, 669 (2006)] where the free fall collapse of the column and subsequent flow of material onto a plane is represented by a “raining” mass source term into a thin flowing layer of constant density. These modified shallow water equations with Coulomb friction capture the free surface of the flows and key scaling laws for initial sand columns of aspect ratios up to a<10. However, unrealistically high coefficients of friction of μ=0.9 are required to reproduce run-outs observed. Key scaling laws for high aspect ratio columns are also not captured. We thus extend the model of Larrieu (2006) to include an estimation for the interface between the static and flowing regions observed within granular collapses in the laboratory by Lube et al. [Phys. Fluids 19, 043301 (2007)]. An empirical sedimentation term Ls and the instantaneous removal of a static deposit wedge, see...

Defining conditions for bulking and debulking in lahars

Through measurements at Semeru Volcano, East Java, we define the conditions under which bulking (entrainment of sediment and pore water) and debulking (dilution and sedimentation) occur in rain-triggered volcanic floods (lahars). Two observation sites were installed 510 m apart, along the Curah Lengkong River, 11.5 km southeast of Semerus summit. This 30-m-wide box valley, with a gravel and lava base, represents a real-world flume analogy. Pore-pressure sensors provided stage measurements, a broad-band seismograph gave insight into sediment content and frictional-collisional behavior, video cameras were used to measure surface velocities, and direct bucket samples were taken. Eight rainfall-induced lahars were recorded, lasting 1–3 h with heights of 0.5–2 m, peak velocities of 3–7 m/s, and discharges of 25–250 m3/s. Flows ranged from typical (<40 wt% sediment) to coarse and dense hyperconcentrated flows (50–60 wt% sediment). Multiple distinct flow “packets” occurred within the complex lahars, and were used to determine internal changes between sites. From the multiparameter data set at each site, volumetric bulking and wave shortening, due to portions of the lahar accelerating toward the flow front, are identified. Initial debulking of lahars between sites may reflect drainage into the dry substrate. Estimates of discharge and volume at each site lead to the quantification of bulking and debulking by these actively flowing lahars along the channel reach. From this, we observe that bulking can be localized to certain parts of lahars, resulting in intraevent increases in peak discharge that are greater than what would occur if bulking was evenly distributed throughout the flow. Such data are essential for the development of numerical descriptions and hazard models for mass flows.

Assessing emergency management training and exercises

Purpose – The purpose of this paper is to investigate how training or exercises are assessed in local government emergency management organisations.Design/methodology/approach – An investigative review of the resources available to emergency managers across North America and within New Zealand, for the evaluation and monitoring of emergency management training and exercises was conducted. This was then compared with results from a questionnaire based survey of 48 local government organisations in Canada, USA, and New Zealand. A combination of closed and open ended questions was used, enabling qualitative and quantitative analysis.Findings – Each organisations training program, and their assessment of this training is unique. The monitoring and evaluation aspect of training has been overlooked in some organisations. In addition, those that are using assessment methods are operating in blind faith that these methods are giving an accurate assessment of their training. This study demonstrates that it is lar...

Enhancing scientific response in a crisis: evidence-based approaches from emergency management in New Zealand

Contemporary approaches to multi-organisational response planning for the management of complex volcanic crises assume that identifying the types of expertise needed provides the foundation for effective response. We discuss why this is only one aspect, and present the social, psychological and organizational issues that need to be accommodated to realize the full benefits of multi-agency collaboration. We discuss the need to consider how organizational culture, inter-agency trust, mental models, information management and communication and decision making competencies and processes, need to be understood and accommodated in crisis management planning and delivery. This paper discusses how these issues can be reconciled within superordinate (overarching) management structures designed to accommodate multi-agency response that incorporates decision-making inputs from both the response management team and the science advisors. We review the science advisory processes within New Zealand (NZ), and discuss lessons learnt from research into the inter-organisational response to historical eruptions and exercises in NZ. We argue that team development training is essential and review the different types of training and exercising techniques (including cross training, positional rotation, scenario planning, collaborative exercises, and simulations) which can be used to develop a coordinated capability in multiagency teams. We argue that to truly enhance the science response, science agencies must learn from the emergency management sector and embark on exercise and simulation programs within their own organisations, rather than solely participating as external players in emergency management exercises. We thus propose a science-led tiered exercise program, with example exercise scenarios, which can be used to enhance both the internal science response and the interagency response to a national or international event, and provide direction for the effective writing and conduct of these exercises.

A two-layer approach to modelling the transformation of dilute pyroclastic currents into dense pyroclastic flows

Most models of volcanic ash flows assume that the flow is either dilute or dense, with dynamics dominated by fluid turbulence or particle collisions, respectively. However, most naturally occurring flows feature both of these end members. To this end, a two-layer model for the formation of dense pyroclastic basal flows from dilute, collapsing volcanic eruption columns is presented. Depth-averaged, constant temperature, continuum conservation equations to describe the collapsing dilute current are derived. A dense basal flow is then considered to form at the base of this current owing to sedimentation of particles and is modelled as a granular avalanche of constant density. We present results which show that the two-layer model can predict much larger maximum runouts than would be expected from single-layer models, based on either dilute or dense conditions, as the dilute surge can outrun the dense granular flow, or vice versa, depending on conditions.

Human behaviour during and immediately following earthquake shaking: developing a methodological approach for analysing video footage

To reduce earthquake casualties, it is important to understand how human behaviour, during and immediately following earthquake shaking, exposes the individual to increased risk of injury. Research on human behaviour during earthquake shaking has identified three main influences: the environment the individual is located in immediately before and during the earthquake, in terms of where the individual is and who the individual is with at the time of the earthquake; individual characteristics, such as age, gender, previous earthquake experience and earthquake attributes, including intensity and duration of earthquake shaking. However, little research has systematically analysed the immediate human responses to earthquake shaking, mostly due to data constraints and/or ethical considerations. Research on human behaviour during earthquakes has relied on simulations or post-event, reflective interviews and questionnaire studies. Such studies are subject to potential limitations such as the quality of the participant’s memory, recall bias or (perceived) realism of a simulation. Thus, to better understand the relationship between human behaviour and injury, researchers need a robust and repeatable methodology. This paper discusses the development of a systematic process and coding scheme to analyse earthquake video footage of human behaviour during strong earthquake shaking. The coding scheme was developed in a two-part process, combining a deductive and inductive approach. Previous research studies of human behavioural response during earthquake shaking provided the basis for the coding scheme. This was then iteratively refined by applying the coding scheme to a broad range of video footage of people exposed to strong shaking during the Canterbury 2010–2011 earthquake sequence.

Decision-making training in local government emergency management

Purpose – The purpose of this paper is to contribute information and recommendations that could better equip emergency managers to prepare for and respond to emergencies and disasters, with a focus on improving their decision‐making capabilities during response.Design/methodology/approach – A questionnaire‐based survey approach was used in this research and 48 different local government organisations participated. These results were examined in conjunction with contemporary emergency management decision‐making literature. A combination of closed and open ended questions was used, enabling qualitative and quantitative analysis.Findings – Results suggest that while there is information available about decision making, not all emergency managers are aware of the existence of this information or understand its relevance to emergency management. It is likely that those who did have a comprehensive understanding of decision making had gained this knowledge through non‐emergency management‐related courses. In to...

Behavioral Response in the Immediate Aftermath of Shaking: Earthquakes in Christchurch and Wellington, New Zealand, and Hitachi, Japan

This study examines people’s response actions in the first 30 min after shaking stopped following earthquakes in Christchurch and Wellington, New Zealand, and Hitachi, Japan. Data collected from 257 respondents in Christchurch, 332 respondents in Hitachi, and 204 respondents in Wellington revealed notable similarities in some response actions immediately after the shaking stopped. In all four events, people were most likely to contact family members and seek additional information about the situation. However, there were notable differences among events in the frequency of resuming previous activities. Actions taken in the first 30 min were weakly related to: demographic variables, earthquake experience, contextual variables, and actions taken during the shaking, but were significantly related to perceived shaking intensity, risk perception and affective responses to the shaking, and damage/infrastructure disruption. These results have important implications for future research and practice because they identify promising avenues for emergency managers to communicate seismic risks and appropriate responses to risk area populations.

Decision-Making: Preventing Miscommunication and Creating Shared Meaning Between Stakeholders

The effective management and response to either volcanic eruptions or (often prolonged) periods of heightened unrest, is fundamentally dependent upon effective relationships and communication between science advisors, emergency managers and key decision makers. To optimise the effectiveness of the scientific contribution to effective prediction and management decision making, it is important for science advisors or scientific advisory bodies to be cognisant of the many different perspectives, needs and goals of the diverse organisations involved in the response. Challenges arise for scientists as they may need to be embedded members of the wider response multi-agency team, rather than independent contributors of essential information. Thus they must add to their competencies an understanding of the different roles, responsibilities, and needs of each member organisation, such that they can start to provide information implicitly rather than in response to explicit requests. To build this shared understanding, the team situational awareness (understanding of the situation in time and space), and the wider team mental model (a representation of the team functions and responsibilities), requires participating in a response environment together. Facilitating the availability of this capability has training and organizational development implications for scientific agencies and introduces a need for developing new inter-agency relationships and liaison mechanisms well before a volcanic crisis occurs. In this chapter, we review individual and team decision making, and the role of situational awareness and mental models in creating “shared meaning” between agencies. The aim is to improve communication and information sharing, as well as furthering the understanding of the impact that uncertainty has upon communication and ways to manage this. We then review personal and organisational factors that can impact response and conclude with a brief review of methods available to improve future response capability, and the importance of protocols and guidelines to assist this in a national or international context.