Real-time prediction of rain-triggered lahars: incorporating seasonality and catchment recovery

Abstract

Abstract. Rain-triggered lahars are a significant secondary hydrological and geomorphic hazard at volcanoes where unconsolidated pyroclastic material produced by explosive eruptions is exposed to intense rainfall, often occurring for years to decades after the initial eruptive activity. Previous studies have shown that secondary lahar initiation is a function of rainfall parameters, source material characteristics and time since eruptive activity. In this study, probabilistic rain-triggered lahar forecasting models are developed using the lahar occurrence and rainfall record of the Belham River valley at the Soufrière Hills volcano (SHV), Montserrat, collected between April 2010 and April 2012. In addition to the use of peak rainfall intensity (PRI) as a base forecasting parameter, considerations for the effects of rainfall seasonality and catchment evolution upon the initiation of raintriggered lahars and the predictability of lahar generation are also incorporated into these models. Lahar probability increases with peak 1 h rainfall intensity throughout the 2-year dataset and is higher under given rainfall conditions in year 1 than year 2. The probability of lahars is also enhanced during the wet season, when large-scale synoptic weather systems (including tropical cyclones) are more common and antecedent rainfall and thus levels of deposit saturation are typically increased. The incorporation of antecedent conditions and catchment evolution into logistic-regression-based raintriggered lahar probability estimation models is shown to enhance model performance and displays the potential for successful real-time prediction of lahars, even in areas featuring strongly seasonal climates and temporal catchment recovery.

Hydrological control of large hurricane-induced lahars: evidence from rainfall-runoff modeling, seismic and video monitoring

“…Various attempts have been made to define lahar initiation rainfall thresholds at different volcanoes (i.e., Lavigne et al, 2000;van Westen and Daag, 2005;Barclay et al, 2007;Jones et al, 2015Jones et al, , 2017, including Volcán de Colima (Capra et al, 2010). This study focused on better prediction of lahar evolution during extraordinary hydro-meteorological events such as hurricanes, a common long-duration and large-scale rainfall phenomenon in tropical latitudes.…”

“…In perspective, the results presented here can be used to design an EWS for hurricane-induced lahars, i.e., events triggered by longduration and large-scale rainfalls. The most common preevent or advanced EWSs for debris flows are based on empirical correlations between rainfall and debris flow occurrence (e.g., Keefer et al, 1987;Aleotti, 2004;Baum and Godt, 2009;Jones et al, 2017;Wei et al, 2017;Greco and Pagano, 2017). The instruments adopted for debrisflow advance warning are those normally used for hydrometeorological monitoring and consist of telemetry networks of rain gauges and/or weather radar.…”

Volcanic hazard exacerbated by future global warming-driven increase in heavy rainfall

“…Multi-decadal catalogues of reports of volcanic activity reveal that rainfall has historically triggered, facilitated or worsened primary volcanic activity or secondary hazards at over 170 subaerial volcanoes; a strong reminder that the influence of the hydrological cycle in volcanic systems can be substantial (see also figure 1). This link emphasizes the importance of considering rainfall in the development of hazard mitigation strategies [21,62,68], and also underscores the importance of developing novel instrumental monitoring systems [69,70]. The incorporation of meteorological data into volcano monitoring systems has seen some limited adoption [71]; nevertheless, meteorological data is far from being a standard monitoring tool.…”

Volcanic hazard exacerbated by future global warming–driven increase in heavy rainfall.

“…1). This link emphasizes the importance of considering rainfall in the development of hazard mitigation strategies (Barclay et al, 2006;Jones et al, 2017;Pierson et al, 2014), and also underscores the importance of developing novel instrumental monitoring systems (Nagatani et al, 2018;Sanderson et al, 2018). The incorporation of meteorological data into volcano monitoring systems has seen some limited adoption (Global Volcanism Program, 2011b); nevertheless, meteorological data is far from being a standard monitoring tool.…”

“…3a, Fig. 4i) is characterized by sensitivity to heavy rainfall: not only does lahar probability scale directly with rainfall intensity (Jones et al, 2017), but triggered primary volcanic activity has been reported frequently (Barclay et al, 2006;Hicks et al, 2010;Matthews et al, 2002). At Vesuvius (Fig.…”