Mudflows are one of the most common natural hazards; they occur frequently associated with heavy rainfall, earthquakes or other unusual phenomena. They often cause a great loss of life and property. This research will use field studies of an actual large volcanic mudflow that occurred in New Zealand in March 2007. It is proposed to develop and test a computer model that simulates such flows that are a mixture of solid particles and water. An important part of this study is to determine the degree of certainty or uncertainty that is possible in forecasts of future mudflows. Analysis of field measurements will provide the basis for testing and improving the computer model. A careful series of computer simulations will be done to sequentially reproduce the field measurements taken of the actual flow. The results of this process can be analyzed to increase the confidence level in forecasting of similar and smaller mudflows elsewhere in the world. A secondary goal of the project will be to forecast smaller mudflows at a volcano in Ecuador that is currently producing similar destructive flows nearly every week due to heavy rainfall. The model and analysis resulting from this study will allow a better means to make sound predictions of hazard risk for similar flows in the future.
The flow of geologic material mixed with interstitial fluid is a complex process activating physics across many length and time scales. This project will extend the TITAN2D computational environment to include fluid-solid flows, and to test these models using data collected from field studies at Ruapehu, New Zealand. Statistical analysis will probe questions of sensitivity to parameters, and of model and measurement error, and will provide a quantitative basis for prediction. A special focus of this effort is to model and calibrate the March 2007 breakout flow of the crater lake at Ruapehu Volcano in New Zealand. Working closely with colleagues at Massey University, the team will use data they collected in their study of the 2007 breakout to further refine mathematical and statistical models. The colleagues at Massey had instrumented Ruapehu, which allowed them to collect an exceptional data set from this important flow event. These data include pre- and post-event aerial LiDAR and digital photographic surveys that show postevent changes in channel morphology, sediment erosion, and redistribution. In addition, instruments for innovative applications of mechanical, electro-magnetic, vibration, and pressure detection systems provide measurements of velocities, sediment distribution, flow behavior, and erosion/deposition processes within the rapidly moving sediment-water slurries of this event. This unique dataset will enable unparalleled testing and calibration of flow models. Coupled with statistical methodology, these results will serve as a standard against which a new generation of numerical and physical mass-flow models can be calibrated and refined. Data from this project will be of particular interest to groups studying the broader-scale problem of hazards related to eruptions of similar volcanoes elsewhere. Refinement of the TITAN model to forecast smaller flow events is planned by testing it at the recurrent events (on a weekly time-frame) at Tungurahua Volcano in Ecuador.
Scientific objectives: Mudflows are one of the most common natural hazards; they occur frequently associated with heavy rainfall, earthquakes or other extreme natural phenomena. They often cause a great loss of life and property. This research was based on field studies of an actual large volcanic mudflow that occurred in New Zealand in March 2007 for which a unique set of measurements made while this flow was moving. We developed and tested an advanced computer model that simulates such flows that contain a mixture of solid particles (soil and volcanic ash) and water. An important part of this study was to determine the degree of certainty or uncertainty that is possible in forecasts of future mudflows. Our analysis of the field measurements provided useful information for testing and improving computer models of this phenomenon. We made a careful series of computer simulations that were directly compared with the actual test flow in New Zealand. These results have increased our confidence in forecasting similar and smaller mudflows elsewhere in the world, using the new computer code that we developed. Specifically, we have made forecasts of smaller mudflows related to mobilization of volcanic ash by heavy rainfall and snow melting that is currently being used for hazard analysis and mitigation in some mountain communities in Argentina. The model and analysis resulting from this study have allowed researchers to make better predictions of hazard risk for similar flows at other locations. We incorporated our original concepts within a widely-used computational model (TITAN) by extending its application to include fluid-solid flows. We tested the new model using data from theoretical calculations, laboratory studies of similar flows on a small scale, and field data collected by our colleagues at Ruapehu Volcano, New Zealand. Statistical analysis allowed us to probe questions of sensitivity of outcomes to input and measurement error. This provides a more quantitative basis for prediction of natural mudflows. The focus of our effort was to forecast and then to calibrate our model with the March 2007 mudflow flow at Ruapehu. Working with colleagues at Massey University, we used data collected in their study of the 2007 crater breakout flow to test and refine our mathematical and statistical models. Our colleagues at Massey used instruments placed in the Ruapehu channel that allowed them to collect an exceptional data set from this important flow event. Their unique dataset enabled us to apply unparalleled testing and calibration for our flow models. Coupled with statistical methodology, these results serve as a standard against which a new generation of numerical and physical mass-flow models can be calibrated and refined. Data from this project should be of particular interest to groups studying the broader-scale problem of hazards related to eruptions of volcanoes elsewhere in the world. Broader impacts: This research involved cooperation among specialists in the fields of experimental and field studies, mathematical modeling, and numerical simulation. Importantly, it allowed us to identify and quantify computational, input, and observational errors that affect the performance of the resulting mathematical model. This work also aided in development of a new paradigm to account for uncertainty in the description-prediction-observation cycle of science by offering a new means to make sound predictions of hazard risk. This project served as a background for masters and doctoral research students at UB to investigate solid-fluid geophysical flows. In addition, students (M.S. and B.S.) and professionals from Universidad de Nariño in Pasto, Colombia participated in exchange between the two universities and completed thesis projects using the basic model of this research. A Ph.D. student of Maori background participated in field work at Ruapehu Volcano under the supervision of Dr. Shane Cronin at Massey University. Data from this project is of particular interest to groups studying the broader-scale problem of hazards related to eruptions of similar volcanoes elsewhere in the world. Publications using this method were applied to flow models in New Zealand (Ruapehu), mass flows and hazards in Ecuador (Tungurahua), and hazard maps in Colombia (Cerro Machin), Mexico (El Chichon), Peru (El Misti).
