Horizontal Ground Deformation Research Articles

Automated near-field deformation detection from mobile laser scanning for the 2014 Mw 6.0 South Napa earthquake

Abstract Quantifying off-fault deformation in the near field remains a challenge for earthquake monitoring using geodetic observations. We propose an automated change detection strategy using geometric primitives generated using a deep neural network, random sample consensus and least squares adjustment. Using mobile laser scanning point clouds of vineyards acquired after the magnitude 6.0 2014 South Napa earthquake, our results reveal centimeter-level horizontal ground deformation over three kilometers along a segment of the West Napa Fault. A fault trace is detected from rows of vineyards modeled as planar primitives from the accumulated coseismic response, and the postseismic surface displacement field is revealed by tracking displacements of vineyard posts modeled as cylindrical primitives. Interpreted from the detected changes, we summarized distributions of deformation versus off-fault distances and found evidence of off-fault deformation. The proposed framework using geometric primitives is shown to be accurate and practical for detection of near-field off-fault deformation.

Mindlin solution on ground deformation caused by the trench excavation during installation of concrete diaphragm wall panels

Concrete diaphragm walls (CDWs) are widely used as support of deep excavation in soft ground in urban areas. Ground deformation occurs during the excavation of trenches for the installation of the CDW panels due to ground stress release. This paper investigates the ground deformation during slurry trenching using Mindlin solution. The pressure of slurry used to protect the trench stability during excavation is simulated as a triangularly distributed load on the trench walls, the soil stress state is solved using Mindlin solution, and the horizontal and vertical ground displacement are obtained through integral transformation of ground strain. The rationality of the solution is verified through comparison between the analytical solution and field measurement. Sensitivity analyses are performed on soil elastic modulus, Poisson's ratio, trench excavation depth and panel length. Simplified formulation is proposed for the prediction of horizontal ground deformation. The impact of excavation stages and adjacent panels on the ground deformation is explored. The study finds that the Mindlin solution is able to provide an approximate solution on the ground deformation during slurry trenching, and the simplified formulation can be used to provide a fast estimate of the horizontal ground movement in engineering practice.

Insights Into Mount Etna December 2018 Eruption From Joint Inversion of Deformation and Gravity Data

AbstractWe present results of the joint analysis of ground deformation and superconducting gravity data encompassing Etna's December 2018 eruption. The horizontal ground deformation points to a mechanism of dike opening. Accordingly, we consider forward analytical models describing the effects of a tensile dislocation and use two data inversion approaches, based on heuristic and probabilistic methods. The observed changes can be explained assuming the intrusion of a fluid lighter than bubble‐free magma, along a dike‐like structure. However, the poor fit to the vertical deformation and the discrepancy between bulk volume increase, deduced by the data inversion (some tens of millions of m3), and volume emitted through effusive activity (∼1 × 106 m3) suggest that a more complex mechanism led to the eruption, involving partial inelastic accommodation of the strain and the formation of void space through increase in the fracturing rate of the medium.

Two-Dimensional Ground Deformation Monitoring in Shanghai Based on SBAS and MSBAS InSAR Methods

Shanghai has experienced the greatest land subsidence in China in the past sixty years and produced undesirable environmental impact. However, horizontal ground deformation has not been understood yet. Therefore ground deformation monitoring together with the analysis of its driving forces are critical for geo-hazards early-warning, city planning and sustainable urbanization in Shanghai. In this paper, two-dimensional ground deformation monitoring was performed in Shanghai with SBAS and MSBAS InSAR methods. Twenty-nine Multi-Look Fine 6 (MF6) Radar-sat-2 SLC data acquired during 2011-2013 were used to derive vertical ground deformation. Meanwhile, six descending Multi-Look Fine 6 (MF6) and four ascending Multi-Look Fine 2 (MF2) spanning April to August, 2008, were used to derive vertical and horizontal ground deformation during the observation period. The results indicate that vertical and horizontal deformations in 2008 were not homogeneously distributed in different districts ranging from 0-2 cm/year. Vertical de-formation rate during 2011-2013 were decreased to less than 1 cm/year in most district of Shanghai area. Activities from groundwater exploitation and rapid urbanization are responsible for most of the ground deformation in Shanghai. Thus, future ground deformation in vertical and horizontal directions should be warranted.

Vertical & horizontal ground deformation of Santorini island deduced by DGPS measurements

Santorini is considered to be a dormant volcano with fairly high geodynamic unrest. Two major tectonic NE-SW trending fault zones, Kammeni and Columbo Lines, which intersect the main part of the volcanic edifice, have affected the magma flow at relatively shallow depths enabling the appearance of individual volcanic centers on the island. GPS measurements on a network of 18 stations were carried out in 1994 and 2005 in order to estimate the ground deformation, both in vertical and horizontal component. The results show that the highest amplitude of subsidence (45 mm) and uplift (51 mm) is noticed on Nea Kammeni and Cape Columbo, respectively. Considering the horizontal displacements, it appears that these sites were strongly affected by the above major faulting zones. They vary between 4 mm and 37 mm, where the highest amplitudes are observed at the south-western corner of Thera and Therassia Islands. Their directions seem to correlate with the observed subsidence in the caldera (deflation) and a probable inflation around the area of the sub-marine Columbo Volcano.

Understanding the trigger for the LUSI mud volcano eruption from ground deformation signatures

Abstract The LUSI mud volcano in the sub-district of Porong, Sidoarjo, East Java, Indonesia started to erupt on 29 May 2006. An almost continuous eruption of a mixture of mud, water and gas has occurred around this area since this date. The eruption triggered vertical and horizontal ground deformation. From June 2006 to December 2010, 14 global positioning system campaigns were conducted to observe the ground deformation using c. 50 stations sparsely located up to 10 km from the eruption centre. Field observations of cracks, terrestrial laser scanning and geo-electrical measurements have also been used to infer the ground deformation signature around the LUSI mud volcano. More than 150 pairs of interferograms generated from 66 ALOS PALSAR images from June 2006 to December 2009 have also been used to study the ground deformation caused by the LUSI mud volcano. The LUSI mud eruption began only 200 m from where the Lapindo Inc. oil company was drilling for oil and gas. The drilling may have pierced a deeper high-pressure zone, causing an underground blow-out of the drillhole into a hydrofracture. Alternatively, the magnitude 6.3 Yogyakarta earthquake, which was located c. 275 km from the eruption site and occurred two days before the LUSI eruption, may have shaken the area sufficiently to cause the eruption by reactivating a fault in the region and liquefying the mud. These two hypotheses for triggering the mud volcano have been argued vehemently and still remain controversial. The ground deformation signatures provide important clues to understanding the trigger for the eruption and to solve this controversy. Co-seismic fault reactivation has its own typical ground deformation signature. This study used global positioning system and InSAR techniques, as well as field observations of cracks, terrestrial laser scanning and geo-electrical measurements, to determine the signature of ground deformation around the LUSI mud volcano and to explain the triggering mechanism.

Satellite interferometry for high-precision detection of ground deformation at a carbon dioxide storage site

At the Aquistore CCS site, located in the southeastern Saskatchewan, Canada, carbon dioxide (CO2) is to be injected at variable rates of up to 1500tonne/day. The storage reservoir consists of a dominantly clastic, brine-filled interval (Deadwood and Winnipeg formations) which reside at 3150–3350m depth. Ground deformation at this site is being monitored to track pressure-induced uplift and potential upward migration of CO2 through faults and fractures. Deformation monitoring is conducted using space-borne Differential Interferometric Synthetic Aperture Radar (DInSAR), capable of achieving millimeter precision and meter spatial resolution over the entire monitored area. During June 2012–October 2014, prior to CO2 injection, two ascending and two descending high-resolution RADARSAT-2 data sets were acquired and simultaneously processed with the advanced Multidimensional Small Baseline (MSBAS) DInSAR producing vertical and horizontal East-West deformation time series with six days temporal sampling, four times more frequent than the repeat cycle of each individual data set. Two years of monitoring prior to the onset of (CO2) injection allowed measurement of the deformation field of the background natural and anthropogenic processes. Vertical and horizontal ground deformation was detected with the rates of ±1.0 and ±0.5cm/year and with precision of 0.3 and 0.2cm/year (2σ) correspondingly. Background motion (shape and magnitude) may resemble deformation signals due to potential upward migration of CO2 through faults and fractures. Analytic elastic and poroelastic modeling was performed to estimate the ground deformation that will be produced when injection begins. For this purpose, rock properties determined from geophysical well logs and in situ temperature and pressure were used. For the elastic model it was determined that a maximum of vertical deformation of 1.6cm/year will be located around the injection well, whereas the maximum of horizontal deformation of 0.6cm/year will be located about 3km away from the injection well. For a more realistic poroelastic model, it was determined that maximum vertical deformation will not exceed 1.6cm and maximum horizontal deformation will not exceed 0.1cm/year during the entire 25 year injection cycle. According to this model, the established monitoring network cannot detect predicted horizontal motion since it is below its sensitivity, whereas for detection of vertical motion ground-based monitoring sites need to be installed near and also at distance from the injection well. Six day temporal sampling allows determination of the transient uplift phase. A proposed MSBAS strategy overcomes limitations of the classical DInSAR, such as sparse temporal resolution and the lack of ability to extract individual deformation components from the line-of-sight retrievals, and can be implemented at other onshore CCS sites for operational monitoring, using readily available SAR data.

Measurement of ground displacement from optical satellite image correlation using the free open-source software MicMac

Image correlation is one of the most efficient techniques to determine horizontal ground displacements due to earthquakes, landslides, ice flows or sand dune migrations. Analyzing these deformations allows a better understanding of the causes and mechanisms of the events. By using sub-pixel correlation on before- and after-event ortho-images obtained from high resolution satellite images it is possible to compute the displacement field with high planimetric resolution. In this paper, we focus on measuring the ground displacements due to seismotectonic events. The three sub-pixel correlators used are: COSI-Corr – developed by Caltech, a free, closed-source correlator, dependent on commercial software (ENVI) and widely used by the geoscience community for measuring ground displacement; Medicis – developed by CNES, also a closed-source correlator capable of measuring this type of deformation; and MicMac – developed by IGN, the free open-source correlator we study and tune for measuring fine ground displacements. We measured horizontal ground deformation using these three correlators on SPOT images in three study cases: the 2001 Kokoxili earthquake, the 2005 dyke intrusion in the Afar depression and the 2008 Yutian earthquake.

Liquefaction caused by the 2009 Olancha, California (USA), M5.2 earthquake

The October 3, 2009 (01:16:00 UTC), Olancha M5.2 earthquake caused extensive liquefaction as well as permanent horizontal ground deformation within a 1.2 km 2 area earthquake in Owens Valley in eastern California (USA). Such liquefaction is rarely observed during earthquakes of M ≤ 5.2. We conclude that subsurface conditions, not unusual ground motion, were the primary factors contributing to the liquefaction. The liquefaction occurred in very liquefiable sands at shallow depth (< 2 m) in an area where the water table was near the land surface. Our investigation is relevant to both geotechnical engineering and geology. The standard engineering method for assessing liquefaction potential, the Seed–Idriss simplified procedure, successfully predicted the liquefaction despite the small earthquake magnitude. The field observations of liquefaction effects highlight a need for caution by earthquake geologists when inferring prehistoric earthquake magnitudes from paleoliquefaction features because small magnitude events may cause such features.

Seismic Behavior of Batter Piles: Elastic Response

Several aspects of the seismic response of groups containing nonvertical piles are studied, including the lateral pile-head stiffnesses, the “kinematic” pile deformation, and the “inertial” soil-pile-structure response. A key goal is to explore the conditions under which the presence of batter piles is beneficial, indifferent, or detrimental. Parametric analyses are carried out using three-dimensional finite-element modeling, assuming elastic behavior of soil, piles, and superstructure. The model is first used to obtain the lateral stiffnesses of single batter piles and to show that its results converge to the available solutions from the literature. Then, real accelerograms covering a broad range of frequency characteristics are employed as base excitation of simple fixed-head two-pile group configurations, embedded in homogeneous, inhomogeneous, and layered soil profiles, while supporting very tall or very short structures. Five pile inclinations are considered while the corresponding vertical-pile group results serve as reference. It is found that in purely kinematic seismic loading, batter piles tend to confirm their negative reputation, as had also been found recently for a group subjected to static horizontal ground deformation. However, the total (kinematic plus inertial) response of structural systems founded on groups of batter piles offers many reasons for optimism. Batter piles may indeed be beneficial (or detrimental) depending on, among other parameters, the relative size of the overturning moment versus the shear force transmitted onto them from the superstructure.

Ground deformation and gravity changes on the island of Pantelleria in the geodynamic framework of the Sicily Channel

The island of Pantelleria is an active volcano located in the Sicily Channel (Southern Italy), in the middle of a continental rift system. Since the 1980s the island was periodically surveyed by using geodetic techniques (EDM, levelling, GPS and high precise gravimetry) to monitor the regional and local volcanic dynamics. Gravity data, collected between 1990 and 1998, show short and long wavelength changes due to the combined effect of shallow and deep sources. They reflect, to some degree, the structural setting of the island as delineated by the Bouguer anomaly field, which indicates that the island is broken up into two main basement blocks. The latter are bordered by two lineaments, probably regional faults related to the global geodynamics of the Sicily Channel Rift Zone. Moreover, the inverse correlation between the gravity and altimetric variations suggests that: i) Pantelleria is kinematically divided in two blocks; ii) the observed behaviour is strongly influenced by the geodynamics of the Sicily Channel. A new interpretation of the fully reprocessed data sets is presented, focusing on the spatial–temporal features of the horizontal ground deformation and gravity changes compared to the Bouguer anomaly and altimetric data. This leads to conclude that volcanism on the island has been probably strongly influenced by the global geodynamics of the Sicily Channel, and future eruptions are most likely to occur at the structural boundary separating the two blocks.

Horizontal ground deformation patterns and magma storage during the Puu Oo eruption of Kilauea volcano, Hawaii: episodes 22?42

Horizontal ground deformation measurements were made repeatedly with an electronic distance meter near the Puu Oo eruption site approximately perpendicular to Kilauea's east rift zone (ERZ) before and after eruptive episodes 22–42. Line lengths gradually extended during repose periods and rapidly contracted about the same amount following eruptions. The repeated extension and contraction of the measured lines are best explained by the elastic response of the country rock to the addition and subsequent eruption of magma from a local reservoir. The deformation patterns are modeled to constrain the geometry and location of the local reservoir near Puu Oo. The observed deformation is consistent with deformation patterns that would be produced by the expansion of a shallow, steeply dipping dike just uprift of Puu Oo striking parallel to the trend of the ERZ. The modeled dike is centered about 800 m uprift of Puu Oo. Its top is at a depth of 0.4 km, its bottom at about 2.9 km, and the length is about 1.6 km; the dike strikes N65° E and dips at about 87°SE. The model indicates that the dike expanded by 11 cm during repose periods, for an average volumetric expansion of nearly 500 000 m3. The volume of magma added to the dike during repose periods was variable but correlates positively with the volume of erupted lava of the subsequent eruption and represents about 8% of the new lava extruded. Dike geometry and expansion values are used to estimate the pressure increase near the eruption site due to the accumulation of magma during repose periods. On average, vent pressures increased by about 0.38 MPa during the repose periods, one-third of the pressure increase at the summit. The model indicates that the dikelike body below Puu Oo grew in volume from 3 million cubic meters (Mm3) to about 10–12 Mm3 during the series of eruptions. The width of this body was probably about 2.5–3.0 m. No net long-term deformation was detected along the measured deformation lines.

Electronic distance measuring network monitoring during the Rabaul seismicity/deformational crisis of 1983–1985

Following a dramatic increase in the seismicity and rate of ground deformation at Rabaul Caldera in September 1983, an electronic distance measuring (EDM) network was established in November–December 1983 to provide additional surveillance of the developing volcanic hazard. The network and operational procedure were designed to monitor frequently a large area and to obtain results rapidly. Initially, data reduction was carried out using the conventional refractive index technique to correct for observed atmospheric variables, but the principle of line ratios using modeled atmospheric variables showed promise for accelerating and simplifying data reduction by obviating meteorological considerations. A standard error of ±1.31 ppm using the line ratio reduction technique favorably compares with results obtained by other researchers. Horizontal strain in the east central part of the caldera increased at monthly rates of 10–80 ppm, reaching a peak in April 1984. This peak coincided with the highest monthly rate of earthquake occurrence (13,800) and the largest monthly rate of ground uplift (approximately 80 mm). The greatest amount of horizontal ground deformation recorded during the period 1983–1985 was about 400 mm. After April 1984 the strain rates declined gradually and, in relation to other components of deformation, probably resumed a precrisis level by mid‐1985. Horizontal deformation in the southern part of the caldera was relatively large in comparison to the amount of ground tilt and uplift recorded there. Because of the relatively small number of reflector stations, modeling of the EDM data is somewhat inconclusive. However, a Mogi point source model provides a reasonable fit to the observed deformation in the northern part of the caldera. The point source model and simple axisymmetric models do not provide a good match to the deformation recorded in the southern part of the caldera. The dominance of horizontal deformation there could be explained by a dyke intrusion.