Abstract Moisture-induced landslides are a global geohazard; mitigating the risk posed by landslides requires an understanding of the hydrological and geological conditions present within a given slope. Recently, numerous geophysical studies have been attempted to characterise slow-moving landslides, with an emphasis on developing geoelectrical methods as a hydrological monitoring tool. However, landslides pose specific challenges for processing geoelectrical data in long-term monitoring contexts as the sensor arrays can move with slope movements. Here we present an approach for processing long-term (over 8 years) geoelectrical monitoring data from an active slow-moving landslide, Hollin Hill, situated in Lias rocks in the southern Howardian Hills, UK. These slope movements distorted the initial setup of the monitoring array and need to be incorporated into a time-lapse resistivity processing workflow to avoid imaging artefacts. We retrospectively sourced seven digital terrain models to inform the topography of our imaging volumes, which were acquired by either Unmanned Aerial Vehicle (UAV)-based photogrammetry or terrestrial laser ranging systems. An irregular grid of wooden pegs was periodically surveyed with a global position system, from which distortions to the terrain model and electrode positions can be modelled with thin plate splines. In order to effectively model the time-series electrical resistivity images, a baseline constraint is applied within the inversion scheme; the result of the study is a time-lapse series of resistivity volumes which also incorporate slope movements. The workflow presented here should be adaptable for other studies focussed on geophysical/geotechnical monitoring of unstable slopes.

Electrical Resistivity Tomography

Geohazard

10.1007/s10346-021-01666-w

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Citations (30)

The Relationships between Effective Porosity, Uniaxial Compressive Strength and Sonic Velocity of Intact Borrowdale Volcanic Group Core Samples from Sellafield

Geotechnical and Geological Engineering (2005)

David Entwisle Peter Hobbs Lee Jones David Gunn Michael Raines

Matrix (chemical analysis)

10.1007/s10706-004-2143-x

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Citations (93)

An overview of lava dome evolution, dome collapse and cyclicity at Soufrière Hills Volcano, Montserrat, 2005–2007

Geophysical Research Letters (2010)

Susan Loughlin Richard Luckett G. Ryan T. Christopher V. Hards

The third episode of lava dome growth at Soufrière Hills Volcano, Montserrat was characterised by higher average magma discharge rates than either previous dome growth episode at this volcano and yet fewer collapses. During sustained dome growth at moderate‐high average rates (>6 m 3 /s), we identified 2–6 week discharge pulses that each supplied c.20 Mm 3 magma from depth. Our observations are consistent with some existing models but we explain discrepancies by a combination of higher volatile contents and higher ascent rates. Cycles of c. 11–16 days were evident in rockfall, LP rockfall and shallow LP earthquake counts related to dome growth and degassing. We speculate that degassing at the conduit margins together with stick‐slip conduit flow may drive these cycles. Only one major collapse >10 Mm 3 occurred during the third episode (on May 20, 2006) as a new magma pulse entered the dome and coincided with heavy rainfall.

Dome (geology)

Lava dome

Electrical conduit

10.1029/2010gl042547

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Citations (61)

Establishment of a baseline DEM on the Soufriere Hills Volcano, Montserrat, using terrestrial LiDAR

Lee Jones

This report provides the results of a study by the British Geological Survey (BGS). It refers to work carried out on behalf of the Montserrat Volcano Observatory (MVO), under the International Business Development (IBD) and the Physical Hazards Programmes of the BGS. This report details the first phase of work carried out to investigate the nature and instability of the Soufriere Hills Volcano, Montserrat, West Indies. The purpose of the monitoring programme is to provide the best possible information to the MVO to assist in decisions about the long-term management of the current volcanic crisis. This primary aim of the survey was to provide a ‘baseline’ survey, incorporating a terrestrial LiDAR (Light Distance And Ranging) survey of the volcanic crater to allow a future assessment to be made, based on subsequent periodic ‘monitoring’ surveys of any changes in the conditions, in particular, the continued growth of a new lava dome or the potential weakening of the crater walls.

Baseline (sea)

Geological survey

Lava dome

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Testing the utility of structure‐from‐motion photogrammetry reconstructions using small unmanned aerial vehicles and ground photography to estimate the extent of upland soil erosion

Earth Surface Processes and Landforms (2017)

Miriam Glendell Gareth McShane Luke Farrow M. R. James John Quinton

Abstract Quantifying the extent of soil erosion at a fine spatial resolution can be time consuming and costly; however, proximal remote sensing approaches to collect topographic data present an emerging alternative for quantifying soil volumes lost via erosion. Herein we compare terrestrial laser scanning (TLS), and both unmanned aerial vehicle (UAV) and ground photography (GP) structure‐from‐motion (SfM) derived topography. We compare the cost‐effectiveness and accuracy of both SfM techniques to TLS for erosion gully surveying in upland landscapes, treating TLS as a benchmark. Further, we quantify volumetric soil loss estimates from upland gullies using digital surface models derived by each technique and subtracted from an interpolated pre‐erosion surface. Soil loss estimates from UAV and GP SfM reconstructions were comparable to those from TLS, whereby the slopes of the relationship between all three techniques were not significantly different from 1:1 line. Only for the TLS to GP comparison was the intercept significantly different from zero, showing that GP is more capable of measuring the volumes of very small erosion features. In terms of cost‐effectiveness in data collection and processing time, both UAV and GP were comparable with the TLS on a per‐site basis (13.4 and 8.2 person‐hours versus 13.4 for TLS); however, GP was less suitable for surveying larger areas (127 person‐hours per ha −1 versus 4.5 for UAV and 3.9 for TLS). Annual repeat surveys using GP were capable of detecting mean vertical erosion change on peaty soils. These first published estimates of whole gully erosion rates (0.077 m a −1 ) suggest that combined erosion rates on gully floors and walls are around three times the value of previous estimates, which largely characterize wind and rainsplash erosion of gully walls. Copyright © 2017 John Wiley & Sons, Ltd.

Aerial photography

Structure from Motion

Ground truth

10.1002/esp.4142

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Ground-based structure from motion - multi view stereo (SFM-MVS) for upland soil erosion assessment.

EGUGA (2016)

Gareth McShane M. R. James John Quniton Luke Farrow Miriam Glendell

Structure from Motion

Gully Erosion

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Coastal landslide monitoring at Aldbrough, East Riding of Yorkshire, UK

Quarterly Journal of Engineering Geology and Hydrogeology (2019)

Peter Hobbs Lee Jones Matt Kirkham Catherine Pennington D. J. R. Morgan

The paper describes results to date of a continuing monitoring study of coastal ‘soft cliff’ recession at the British Geological Survey's (BGS's) Coastal Landslide Observatory (CLO) on the east coast of England at Aldbrough, East Riding of Yorkshire. The cliffed site, part of the 50 km long Holderness coast, consists of glacial deposits, and is one of the most rapidly eroding coastlines in Europe. This rapid rate of erosion provides an ideal opportunity for observation and process understanding because it facilitates the collection of data over periods of time encompassing significant new landslide events at the same location. The results of two approaches are reported: first, terrestrial Light Detection and Ranging (LiDAR) surveying (TLS); second, the installation of instrumented boreholes. The aim of the research is to combine these to investigate the role of landslides and their pre-conditioning factors and the influence of geology, geotechnics, topography and environmental factors on cliff recession. To date, an average recession rate of 1.8 m a −1 and a maximum rate of 3.4 m a −1 have been recorded for the site. The establishment of the CLO and its conceptual geological–geotechnical model are described in a related paper.

10.1144/qjegh2018-210

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Structural evolution triggers a dynamic reduction in active glacier length during rapid retreat: Evidence from Falljökull, SE Iceland

Journal of Geophysical Research Earth Surface (2014)

Emrys Phillips Andrew Finlayson Tom Bradwell Jez Everest Lee Jones

Abstract Over the past two decades Iceland's glaciers have been undergoing a phase of accelerated retreat set against a backdrop of warmer summers and milder winters. This paper demonstrates how the dynamics of a steep outlet glacier in maritime SE Iceland have changed as it adjusts to recent significant changes in mass balance. Geomorphological evidence from Falljökull, a high‐mass turnover temperate glacier, clearly shows that between 1990 and 2004 the ice front was undergoing active retreat resulting in seasonal oscillations of its margin. However, in 2004–2006 this glacier crossed an important dynamic threshold and effectively reduced its active length by abandoning its lower reaches to passive retreat processes. A combination of ice surface structural measurements with radar, lidar, and differential Global Navigation Satellite Systems data are used to show that the upper active section of Falljökull is still flowing forward but has become detached from and is being thrust over its stagnant lower section. The reduction in the active length of Falljökull over the last several years has allowed it to rapidly reequilibrate to regional snowline rise in SE Iceland over the past two decades. It is possible that other steep, mountain glaciers around the world may respond in a similar way to significant changes in their mass balance, rapidly adjusting their active length in response to recent atmospheric warming.

Glacier mass balance

Tidewater glacier cycle

Glacier terminus

Glacier ice accumulation

Glacier morphology

10.1002/2014jf003165

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Citations (27)

Improved modelling and communication of urban risks : case studies from the United Kingdom and South-East Asia

Peter Hobbs Andy Gibson Nick Koor John Rees Simon James Price

This paper uses recent studies to demonstrate how modern developments, including remote sensing, 3-D modelling and responsive surveys, have enabled scientists to better understand urban geological environments and geohazards and communicate them to the public. These developments are discussed here and illustrated with three diverse examples from the UK and SE Asia.

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