Conceptualizing the hydrogeothermal setting of Sloquet Hot Springs in the Canadian Cordillera on unceded St'at'imc Territory: an example of a reconciliation-based approach to field geoscience

Field geoscience has made important scientific advances but has not consistently considered the impact of these geoscience results on communities where the fieldwork is conducted. A reconciliation-based approach calls for critical thought about who defines, participates in, owns, and uses geoscience research, particularly in light of unresolved aboriginal rights and title claims and treaty rights throughout all of Canada. Geothermal research in the Canadian Cordillera has typically focused on hot spring systems and predicting maximum temperatures at depth, estimating fluid circulation depths, and investigating the distribution of hot spring systems and their relation to major geological features that often control thermal fluid flow. Detailed fieldwork to develop local and regional conceptual models of these systems has rarely been conducted and to our best knowledge, never in partnership with a First Nation. The scope of this project was working collaboratively with Xa’xtsa First Nation to conduct detailed structural, hydrologic and hydrogeologic fieldwork to develop local and regional conceptual models of Sloquet Hot Springs, on unceded St'at'imc territory. To motivate our research and provide a successful example of a reconciliation-based approach to field geoscience, we review how resource regulation, research, relationships, and reconciliation interact in British Columbia and consider our community partnership relative to Wong et al (2020)’s 10 Calls for Action for Natural Scientists. Well drilling, testing and monitoring revealed numerous soft zones in the subsurface as well as high transmissivity suggesting bedrock in the area has significant permeability. The annual flux calculated for Sloquet Hot Springs suggests a regional flow contribution from nearby watersheds. Although surface and subsurface observations did not identify the primary fault that conveys high-temperature fluids, the potential locations of buried fault structures are hypothesized based on zones with observably high temperatures and flow along Sloquet Creek. These results and interpretations are synthesized into a conceptual model of a localized hydrogeothermal system with local and regional groundwater flow along permeable pathways in the subsurface and mixing with cooler water before discharging in some of the springs.

Geomorphologically-controlled seismic signals at Mount St. Helens volcano

<p>In volcanoes, topography and shallow morphology can substantially modify seismic signals, tracing anisotropic signatures in the crust's most surficial layers. To better understand the influence of key morphologies, forward modelling of the seismic waveforms is fundamental.  Here, we introduce a forward model of the seismic wave equation developed with finite-differences schemes in anisotropic viscoelastic media. The observation of geomorphological features and the surficial geology map of Mount St. Helens are used to reproduce the scattering and anisotropic effects caused by shallow heterogeneity on seismic signals. The main aim is to understand if and to which lengths lateral anisotropic variations in geomorphological features control the generation and propagation of low-frequency seismic signals, focusing especially on the timing of surface-wave enhancement.</p><p>The model shows how the geomorphology-derived anisotropy controls the travel times of the horizontally polarized S waves (SH), in particular along with two directions: WNW-ESE, following the trend of a buried fault, and NS, consistent with the main morphological difference between southern (mostly untouched by the 1980 eruption) and northern (collapsed in 1980’s blast) flanks of the volcano. An analysis of the waveforms of a shallow event of 2005 (during the last eruption of Mt. St. Helens), located in the crater, shows how an isotropic model can reproduce the arrival of the SH wave at high frequencies (10 Hz). The introduction of an effective anisotropic medium is necessary to explain the arrivals for stations deployed across the north-northwestern flank of the volcano at lower frequencies (1 Hz and 6 Hz). The heterogeneity in the crater (e.g., the glacier inside the crater covered by a rock-debris layer) can create interfaces made mostly of unconsolidated materials. As also demonstrated by radiative transfer simulation, the crater acts as a primary source of surface waves dominating the seismic signals.</p>

Postseismic deformation following the 2016 Kumamoto earthquake detected by ALOS-2/PALSAR-2

I have been conducting a study of postseismic deformation following the 2016 Kumamoto earthquake using ALOS-2/PALSAR-2 acquired till 2018. I apply ionospheric correction to interferograms of ALOS-2/PALSAR-2. L-band SAR gives us high coherence enough to reveal surface deformation even in vegetated or mountainous area for pairs of images acquired more than 2 years. Postseismic deformation following the Kumamoto earthquake exceeds 10 cm during 2 years at some spots in and around Kumamoto city and Aso caldera. Westward motion of ~ 6 cm/year was dominant on the southeast side of the Hinagu fault, while westward shift was detected on both sides of the Futagawa fault. The area of latter deformation seems to have correlation with distribution of pyroclastic flow deposits. Significant uplift was found around the eastern Futagawa fault and on the southwestern frank of Aso caldera, whose rate reaches 4 cm/year. There are sharp changes across several coseismic surface ruptures such as Futagawa, Hinagu, and Idenokuchi faults. Rapid subsidence between Futagawa and Idenokuchi faults also found. It is confirmed that local subsidence continued along the Suizenji fault, which newly appeared during the mainshock in Kumamoto City. Subsidence with westward shift of up to 4 cm/year was also found in Aso caldera. Time constant of postseismic decay ranges from 1 month to 600 days at selected points, but that postseismic deformation during the first epochs or two is dominant at point in the Kumamoto Plain. This result suggests multiple source of deformation. Westward motion around the Hinagu fault may be explained with right lateral afterslip on the shallow part of this fault. Subsidence along the Suizenji fault can be attributed to normal faulting on dipping westward. Deformation around the Hinagu and Idenokuchi faults cannot be explained with right lateral afterslip of Futagawa fault, which requires other sources. Deformation in northern part of Aso caldera might be the result of right lateral afterslip on a possible buried fault.

Postseismic Deformation Following the 2016 Kumamoto Earthquake Detected by ALOS-2/PALSAR-2

I have been conducting a study of postseismic deformation following the 2016 Kumamoto earthquake using ALOS-2/PALSAR-2 acquired till 2018. I apply ionospheric correction to interferograms of ALOS-2/PALSAR-2. L-band SAR gives us high coherence enough to reveal surface deformation even in vegetated or mountainous area for pairs of images acquired more than 2 years. Postseismic deformation following the Kumamoto earthquake exceeds 10 cm during two years at some spots in and around Kumamoto city and Aso caldera. Westward motion of ~6 cm/yr was dominant on the southeast side of the Hinagu fault, while westward shift was detected on both side of the Futagawa fault. The area of latter deformation seems to have correlation with distribution of pyroclastic flow deposits. Significant uplift was found around the eastern Futagawa fault and on the southwestern frank of Aso caldera, whose rate reaches 4 cm/yr. There are sharp changes across several coseismic surface ruptures such as Futagawa, Hinagu, and Idenokuchi faults. Rapid subsidence between Futagawa and Idenokuchi faults also found. It is confirmed that local subsidence continued along the Suizenji fault, which newly appeared during the mainshock in Kumamoto City. Subsidence with westward shift of up to 4 cm/yr was also found in Aso caldera.Time constant of postseismic decay ranges from 1 month to 600 days at selected points, but that postseismic deformation during the first epochs or two are dominant at point in the Kumamoto Plain. This result suggests multiple source of deformation. Westward motion around the Hinagu fault may be explained with right lateral afterslip on the shallow part of this fault. Subsidence along the Suizenji fault can be attributed to normal faulting on dipping westward. Deformation around the Hinagu and Idenokuchi faults cannot be explained with right-lateral afterslip of Futagawa fault, which requires other sources. Deformation in northern part of Aso caldera might be the result of right lateral afterslip on a possible buried fault.

Postseismic Deformation Following the 2016 Kumamoto Earthquake Detected by ALOS-2/PALSAR-2

I have been conducting a study of postseismic deformation following the 2016 Kumamoto earthquake using ALOS-2/PALSAR-2 acquired till 2018. I apply ionospheric correction to interferograms of ALOS-2/PALSAR-2. L-band SAR gives us high coherence enough to reveal surface deformation even in vegetated or mountainous area for pairs of images acquired more than 2 years. Postseismic deformation following the Kumamoto earthquake exceeds 10 cm during two years at some spots in and around Kumamoto city and Aso caldera. Westward motion of ~6 cm/yr was dominant on the southeast side of the Hinagu fault, while westward shift was detected on both side of the Futagawa fault. The area of latter deformation seems to have correlation with distribution of pyroclastic flow deposits. Significant uplift was found around the eastern Futagawa fault and on the southwestern frank of Aso caldera, whose rate reaches 4 cm/yr. There are sharp changes across several coseismic surface ruptures such as Futagawa, Hinagu, and Idenokuchi faults. Rapid subsidence between Futagawa and Idenokuchi faults also found. It is confirmed that local subsidence continued along the Suizenji fault, which newly appeared during the mainshock in Kumamoto City. Subsidence with westward shift of up to 4 cm/yr was also found in Aso caldera. Time constant of postseismic decay ranges from 1 month to 600 days at selected points, but that postseismic deformation during the first epochs or two are dominant at point in the Kumamoto Plain. This result suggests multiple source of deformation. Westward motion around the Hinagu fault may be explained with right lateral afterslip on the shallow part of this fault. Subsidence along the Suizenji fault can be attributed to normal faulting on dipping westward. Deformation around the Hinagu and Idenokuchi faults cannot be explained with right-lateral afterslip of Futagawa fault, which requires other sources. Deformation in northern part of Aso caldera might be the result of right lateral afterslip on a possible buried fault.

Different disaster characteristics of earth fissures and their influence factors in the Beijing plain

To analyze the generation of different ground fissure disasters, two typical ground fissures were selected. With geological survey and exploration data, the spatial characteristics of the Songzhuang and Gaoliying fissures were investigated. The different occurrence factors for the Songzhuang and Gaoliying fissures were analyzed based on geological structure and groundwater. The conclusions contain are as follows. The affected body of the Songzhuang fissure exhibits obvious tensile deformation, and it is not contact with buried faults. The fracture-affected body of the Gaoliying fissure shows obvious vertical dislocation and shear, and this is compounded with buried faults. The distribution characteristic of the Songzhuang fissure was controlled by the tectonics and the normal fault, while the buried fault not only control the distribution feature of the Gaoliying fissure but also controlled its deformation characteristic. A buried fault is the geological background for the formation of the Gaoliying fissure. The long-term exploitation of groundwater has caused the horizontal deformation of the soil and the rigid rotation of stratum in the subsidence edge. Both of them are the reason for the tensile deformation. Due to the activities of buried faults and differential subsidence in small areas, the affected bodies of the Gaoliying fissure showed vertical dislocation and shear deformation.

The Study of Crustal Velocity Structure Characteristics in Yangjiang Area of South China

<p>This paper collects 43,225 absolute first arrival P wave arrival times and 422,956 high quality relative P arrival times of 6,390 events occurred in Yangjiang and its adjacent area from Jan, 1990 to Aug, 2019, these seismic data is recorded by 49 stations from Guangdong seismic network, Guangxi seismic network and Hainan seismic network. Based on the seismic data above, we simultaneously determine the crustal 3D P wave velocity structure and the hypocenter parameters of 6255 events in Yangjiang and its adjacent area by applying Double-Difference seismic tomography. The result shows that, shallow P wave velocity in Yangjiang area is higher due to the thinner sedimentary layer and widely exposed Yanshanian granite, Indosinian granite and Cambrian metamorphic rocks. There are obvious correspondences between the distribution of shallow velocity and fault structure as well as geological structure. A wide range of low velocity anomaly exists in 20km depth, which verifies the low velocity layer in the middle crust at Yangjiang area of South China continent. The velocity image from land to ocean in 30km depth shows low velocity in NW side and high velocity in SE side, which verifies the characteristic of crust thinning in South China coastal continent. The NEE seismic belt from Yangbianhai to Pinggang is speculated to locate in a buried fault of southwest segment of Pinggang fault. The buried thrust fault is a N78°E strike fault, dip to NW with a dip angle of 85 °. In addition, the buried fault locates in the abnormal junction of high velocity on the NW side and low velocity on the SE side, which reflects the tectonic activity characteristic of NW plate uplifting and SE plate declining from Miocene period. The characteristic of activity in the buried fault shows thrust movement with a small strike slip component, which is consistent with the focal mechanism of M4.9 earthquake occurred in 2004.</p>

The assessment of earthquake-triggered landslides susceptibility with considering coseismic ground deformation

The distance to the surface rupture zone has been commonly regarded as an important influencing factor in the evaluation of earthquake-triggered landslides susceptibility. However, the obvious surface rupture zones usually do not occur in some buried-fault earthquakes cases, which mean lacking of the information about the distance to the surface rupture. In this study, a new influencing factor named coseismic ground deformation was added to remedy this shortcoming. The Mid-Niigata prefecture earthquake was regareded as the study case. In order to select a more suitable model for generating the landslides susceptibility map, three commonly used models named Logistic Regression (LR), Artificial Neural Networks (ANN) and Support Vector Machines (SVM) were also conducted to assess the landslides susceptibility. The performances of these three models were evaluated with the receiver operating characteristic (ROC) curve. The calculated results showed the ANN model has the highest AUC (area under the curve) value of 0.82. As the earthquake triggered more landslides in the epicenter area, which makes it more prone to landslides in further earthquakes, the landslides susceptibility in the epicenter area was also further evaluated.

Characterization of Geological Structures under Thick Quaternary Formations with CSAMT Method in Taiyuan City, Northern China

A controlled-source audio-frequency magnetotelluric (CSAMT) survey was used to detect geological structures beneath the thick quaternary formation in Taiyuan, Shanxi Province, northern China. Two main CSAMT survey lines with 182 survey sites were recorded. A two-dimensional (2D) inversion technique was used to interpret the CSAMT data. The inversion results suggested that: 1) there are four main buried faults named F1, F2, F3, and F4 with dip angles about 65° across the survey line from west to east, the fault displacements of these faults are about 230 m, 180 m, 220 m and 200 m, respectively; 2) the depth of the bedrocks decrease from 1600 to 500 m along the survey lines; and 3) from top to bottom, there are four major layers in the survey area that include the upper layer with the resistivity less than 40 ohm-m represents unconsolidated sediments in the Quaternary formation, a second layer with the resistivity range from 40 to 120 ohm-m represents mudstone and sandstone, a third layer with the resistivity range from 120 to 280 ohm-m represents coal measure strata in the Permian and Carboniferous and a bottom layer with the resistivity higher than 280 Ω·m represents limestone in Ordovician. The CSAMT method is an effective technique for exploring buried fault of several hundred meters deep in metropolitan environment.