scholarly journals Ghost tilt signal during transient ground surface deformation events: Insights from the September 3, 2010 Mw7.1 Darfield earthquake, New Zealand

2011 ◽  
Vol 38 (16) ◽  
pp. n/a-n/a ◽  
Author(s):  
Nicolas Fournier ◽  
Arthur D. Jolly ◽  
Craig Miller
Keyword(s):  
New Zealand ◽  
Surface Deformation ◽  
Ground Surface ◽  
Tilt Signal

scholarly journals Geodetic, hydrologic and seismological signals associated with precipitation and infiltration in the central Southern Alps, New Zealand

2021 ◽  
Author(s):  
◽  
Nicolas Oestreicher
Keyword(s):  
New Zealand ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Ground Surface ◽  
Southern Alps ◽  
Hydrologic Cycle ◽  
Geodetic Data ◽  
Surface Processes ◽  
Groundwater Levels ◽  
Seismicity Rates

<p>The Southern Alps of New Zealand is an actively deforming mountain range, along which collision between the Pacific and Australian plates is manifest as elevated topography, orographic weather, active contemporary deformation, and earthquakes. This thesis examines interactions between surface processes of meteorological and hydrological origin, the ground surface deformation, and processes within the seismogenic zone at depth. The two main objectives of the thesis are a better understanding of the reversible repetitive ground surface deformation in the central Southern Alps and the analysis of the evolution of the rate of microseismicity in the area to explore relationships between seismicity rates and the hydrologic cycle.  Surface deformation in the central Southern Alps is characterised by a network of 19 continuous GPS stations located between the West Coast (west) and the Mackenzie Basin (east), and between Hokitika (north) to Haast (south). These show repetitive and reversible movements of up to ∼55mm on annual scales, on top of long-term plate motion, during a 17 year-long period. Stations in the high central Southern Alps exhibit the greatest annual variations, whereas others are more sensitive to changes following significant rain events. Data from 22 climate stations (including three measuring the snowpack), lake water levels and borehole pressure measurements, and numerical models of solid Earth tides and groundwater levels in bedrock fractures, are compared against geodetic data to examine whether these environmental factors can explain observed patterns in annual ground deformation. Reversible ground deformation in the central Southern Alps appears strongly correlated with shallow groundwater levels. Observed seasonal fluctuation and deformation after storm events can be explained by simple mathematical models of groundwater levels. As a corollary, local hydrological effects can be accounted for and ameliorated during preprocessing to reduce noise in geodetic data sets being analysed for tectonic purposes.  Two catalogues of earthquakes (containing 38 909 and 89 474 events) in the area spanning the period 2008–2017 were built using a matched-filtered detection technique. The smaller catalogue is based on 211 template events, each of known focal mechanism, while the latter is based on 902 templates, not all of which have focal mechanisms, providing greater temporal resolution. Microseismicity data were examined in both time and frequency domains to explore relationships between seismicity rates and the hydrologic cycle. Microseismicity shows a pronounced seasonality in the central Southern Alps, with significantly more events detected during winter than during summer. These changes cannot be easily accounted for by either acquisition or analysis parameters. Two models of hydrologically-induced seasonal seismicity variations have been considered — surface water loading and deep groundwater circulation of meteoric fluids — but neither model fully explains the observations, and further work is required to explain them fully. An observed diurnal variation in earthquake detection rate is believed to originate mostly from instrumental effects, which should be accounted for in future seismological studies of earthquake occurrence in the central Southern Alps.  Relationships and correlations observed between hydrological, geodetic, and seismological data from the central Southern Alps provide clear indications that surface processes exert at least some degree of influence on upper-crustal seismicity adjacent to the Alpine Fault.</p>

scholarly journals Geodetic, hydrologic and seismological signals associated with precipitation and infiltration in the central Southern Alps, New Zealand

2021 ◽  
Author(s):  
◽  
Nicolas Oestreicher
Keyword(s):  
New Zealand ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Ground Surface ◽  
Southern Alps ◽  
Hydrologic Cycle ◽  
Geodetic Data ◽  
Surface Processes ◽  
Groundwater Levels ◽  
Seismicity Rates

<p>The Southern Alps of New Zealand is an actively deforming mountain range, along which collision between the Pacific and Australian plates is manifest as elevated topography, orographic weather, active contemporary deformation, and earthquakes. This thesis examines interactions between surface processes of meteorological and hydrological origin, the ground surface deformation, and processes within the seismogenic zone at depth. The two main objectives of the thesis are a better understanding of the reversible repetitive ground surface deformation in the central Southern Alps and the analysis of the evolution of the rate of microseismicity in the area to explore relationships between seismicity rates and the hydrologic cycle.  Surface deformation in the central Southern Alps is characterised by a network of 19 continuous GPS stations located between the West Coast (west) and the Mackenzie Basin (east), and between Hokitika (north) to Haast (south). These show repetitive and reversible movements of up to ∼55mm on annual scales, on top of long-term plate motion, during a 17 year-long period. Stations in the high central Southern Alps exhibit the greatest annual variations, whereas others are more sensitive to changes following significant rain events. Data from 22 climate stations (including three measuring the snowpack), lake water levels and borehole pressure measurements, and numerical models of solid Earth tides and groundwater levels in bedrock fractures, are compared against geodetic data to examine whether these environmental factors can explain observed patterns in annual ground deformation. Reversible ground deformation in the central Southern Alps appears strongly correlated with shallow groundwater levels. Observed seasonal fluctuation and deformation after storm events can be explained by simple mathematical models of groundwater levels. As a corollary, local hydrological effects can be accounted for and ameliorated during preprocessing to reduce noise in geodetic data sets being analysed for tectonic purposes.  Two catalogues of earthquakes (containing 38 909 and 89 474 events) in the area spanning the period 2008–2017 were built using a matched-filtered detection technique. The smaller catalogue is based on 211 template events, each of known focal mechanism, while the latter is based on 902 templates, not all of which have focal mechanisms, providing greater temporal resolution. Microseismicity data were examined in both time and frequency domains to explore relationships between seismicity rates and the hydrologic cycle. Microseismicity shows a pronounced seasonality in the central Southern Alps, with significantly more events detected during winter than during summer. These changes cannot be easily accounted for by either acquisition or analysis parameters. Two models of hydrologically-induced seasonal seismicity variations have been considered — surface water loading and deep groundwater circulation of meteoric fluids — but neither model fully explains the observations, and further work is required to explain them fully. An observed diurnal variation in earthquake detection rate is believed to originate mostly from instrumental effects, which should be accounted for in future seismological studies of earthquake occurrence in the central Southern Alps.  Relationships and correlations observed between hydrological, geodetic, and seismological data from the central Southern Alps provide clear indications that surface processes exert at least some degree of influence on upper-crustal seismicity adjacent to the Alpine Fault.</p>

scholarly journals Imaging ground surface deformations in post-disaster settings via small UAVs

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Richard L. Ybañez ◽  
Audrei Anne B. Ybañez ◽  
Alfredo Mahar Francisco A. Lagmay ◽  
Mario A. Aurelio
Keyword(s):  
Surface Deformation ◽  
Ground Surface ◽  
Point Clouds ◽  
Lateral Spreading ◽  
Fault Movement ◽  
Field Surveys ◽  
3D Point Clouds ◽  
Vertical Displacements ◽  
Resolution Imaging ◽  
Post Disaster

AbstractSmall unmanned aerial vehicles have been seeing increased deployment in field surveys in recent years. Their portability, maneuverability, and high-resolution imaging are useful in mapping surface features that satellite- and plane-mounted imaging systems could not access. In this study, we develop and apply a workplan for implementing UAV surveys in post-disaster settings to optimize the flights for the needs of the scientific team and first responders. Three disasters caused by geophysical hazards and their associated surface deformation impacts were studied implementing this workplan and was optimized based on the target features and environmental conditions. An earthquake that caused lateral spreading and damaged houses and roads near riverine areas were observed in drone images to have lengths of up to 40 m and vertical displacements of 60 cm. Drone surveys captured 2D aerial raster images and 3D point clouds leading to the preservation of these features in soft-sedimentary ground which were found to be tilled over after only 3 months. The point cloud provided a stored 3D environment where further analysis of the mechanisms leading to these fissures is possible. In another earthquake-devastated locale, areas hypothesized to contain the suspected source fault zone necessitated low-altitude UAV imaging below the treeline capturing Riedel shears with centimetric accuracy that supported the existence of extensional surface deformation due to fault movement. In the aftermath of a phreatomagmatic eruption and the formation of sub-metric fissures in nearby towns, high-altitude flights allowed for the identification of the location and dominant NE–SW trend of these fissures suggesting horst-and-graben structures. The workplan implemented and refined during these deployments will prove useful in surveying other post-disaster settings around the world, optimizing data collection while minimizing risk to the drone and the drone operators.

Strike-slip ground-surface rupture (Greendale Fault) associated with the 4 September 2010 Darfield earthquake, Canterbury, New Zealand

2011 ◽  
Vol 44 (3) ◽  
pp. 283-291 ◽  
Author(s):  
D.J.A. Barrell ◽  
N.J. Litchfield ◽  
D.B. Townsend ◽  
M. Quigley ◽  
R.J. Van Dissen ◽  
...  
Keyword(s):  
New Zealand ◽  
Ground Surface ◽  
Strike Slip ◽  
Surface Rupture

3D Visual Technology of Geo-Deformation Disasters Induced by Mining Subsidence Based on ArcGIS Engine

2012 ◽  
Vol 500 ◽  
pp. 428-436 ◽  
Author(s):  
Ke Ming Yang ◽  
Jun Ting Ma ◽  
Bo Pang ◽  
Yi Bin Wang ◽  
Ran Wang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Mining Subsidence ◽  
Underground Coal Mining ◽  
Vertical Movements ◽  
Probability Integral Method ◽  
Arcgis Engine

Mining subsidence often produces significant horizontal and vertical movements at the ground surface, the surface deformation induced by underground coal mining can be predicted by probability integral method, and the surface geo-deformation disasters can be visualized based on GIS components. A three dimensional (3D) visualizing system of surface geo-deformation information is designed and developed with ArcGIS Engine and C# in the study. According to the surface deformation-predicted data induced by underground coal mining in Guobei Coalmine of Huaibei mine field, the extents and degrees of ground deformation disasters are visualized in 3D views for surface vertical subsidence, slope, curvature, horizontal displacement and horizontal strain based on the GIS-developed application platform.

scholarly journals Elastic and non-elastic surface deformation in New Zealand

1970 ◽  
Vol 3 (4) ◽  
pp. 131-142
Author(s):  
G. J. Lensen
Keyword(s):  
New Zealand ◽  
Surface Deformation ◽  
Elastic Surface

Over the last decade it has become evident that not all surface deformation takes place during earthquakes. Deformation associated with earthquakes and their aftershocks appears to be non-elastic in nature, while in between earthquakes deformation appears to be elastic.

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