Spatio-temporal hazard estimation in the Auckland Volcanic Field, New Zealand, with a new event-order model

Abstract

The Auckland Volcanic Field (AVF) with 49 eruptive centres in the last c. 250 ka presents many challenges to our understanding of distributed volcanic field construction and evolution. We re-examine the age constraints within the AVF and perform a correlation exercise matching the well-dated record of tephras from cores distributed throughout the field to the most likely source volcanoes, using thickness and location information and a simple attenuation model. Combining this augmented age information with known stratigraphic constraints, we produce a new age-order algorithm for the field, with errors incorporated using a Monte Carlo procedure. Analysis of the new age model discounts earlier appreciations of spatiotemporal clustering in the AVF. Instead the spatial and temporal aspects appear independent; hence the location of the last eruption provides no information about the next location. The temporal hazard intensity in the field has been highly variable, with over 63% of its centres formed in a high-intensity period between 40 and 20 ka. Another, smaller, high-intensity period may have occurred at the field onset, while the latest event, at 504±5 years B.P., erupted 50% of the entire field's volume. This emphasises the lack of steady-state behaviour that characterises the AVF, which may also be the case in longer-lived fields with a lower dating resolution. Spatial hazard intensity in the AVF under the new age model shows a strong NE-SW structural control of volcanism that may reflect deep-seated crustal or subduction zone processes and matches the orientation of the Taupo Volcanic Zone to the south.

The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy)

“…However, some examples exist: Cox processes have been applied to the assessment of long-term volcanic hazards (e.g., Jaquet et al, 2000Jaquet et al, , 2008Jaquet and Carniel, 2006); self-exciting processes have been introduced for modeling the temporal eruptive pattern of volcanic fields (e.g., Bebbington and Cronin, 2011); a complete long-term PDC hazard assessment procedure has been developed at the Montserrat volcano, combining probability estimates of time, size and direction of the flows (Bayarri et al, 2009(Bayarri et al, , 2015. A detailed review also including other approaches has been described in Bebbington (2013).…”

A combined field and numerical approach to understanding dilute pyroclastic density current dynamics and hazard potential: Auckland Volcanic Field, New Zealand

“…The relatively high sea level and abundant aquifers in the Miocene sediments beneath the AVF indicate a high probability that the initial phase of future AVF eruptions will be phreatomagmatic in nature (Lindsay et al, 2010;Sandri et al, 2012). The probability of a future phreatomagmatic eruption, combined with the uncertainty of vent location and size of a future eruption(s), has motivated focused research on past and possible future phreatomagmatic eruptions and base surges in the AVF (e.g., Searle, 1964;Kermode, 1992;Smith and Allen, 1993;Allen and Smith, 1994;Magill and Blong, 2005;Lindsay et al, 2010;Sandri et al, 2012;Bebbington and Cronin, 2011).…”

Holocene-Neogene volcanism in northeastern Australia: Chronology and eruption history

“…These 397 recognized eruptions are largely from extant cinder cones and craters with prominent topographic exposure, and are dominantly less than ~4 Ma (Stephenson, 1989), which equates to an average of one eruption every 10 ka. For comparison, this is only moderately less frequent than the eruption rate in the better-known Auckland volcanic field, which over the last 140 ka has on average ~3 ka between eruptions (Smith and Allen, 1993), with as little as ~1.8 ka between eruptions around 30 ka ago (Bebbington and Cronin, 2010).…”

“…We note that the actual eruption rate is likely more frequent than either of these estimates, as the numbers of eruptions dated and mapped are minimum values. Also, by analogy with other intraplate volcanoes (e.g., Auckland, Bebbington and Cronin, 2010), the eruption frequency likely fluctuated through time. Nevertheless, the relatively short average recurrence interval, when combined with the youthfulness of the most recent eruptions like Kinrara (Table 1) and additional probable Holocene eruptions in the Atherton province (Whitehead et al, 2007), indicates that volcanism in northern Queensland has the potential for future activity.…”