USING PORE PRESSURE SENSORS TO MONITOR THE MOVEMENT OF WATER LEVEL CHANGES IN THE BODY OF RADOVESICE DUMP

Seasonal trends of reservoir-triggered seismicity in Song Tranh 2 reservoir, Vietnam

10.5194/egusphere-egu21-5495 ◽

2021 ◽

Author(s):

Grzegorz Lizurek ◽

Konstantinos Leptokaropoulos ◽

Jan Wiszniowski ◽

Izabela Nowaczyńska ◽

Nguyen Van Giang ◽

...

Keyword(s):

Water Level ◽

Pore Pressure ◽

Seismic Activity ◽

Water Level Fluctuations ◽

Response Type ◽

Seasonal Trends ◽

Triggered Seismicity ◽

Stress Orientation ◽

Water Level Changes ◽

Pressure Changes

<p>Reservoir-triggered seismicity (RTS) is the longest known anthropogenic seismicity type. It has the potential to generate seismic events of M6 and bigger. Previous studies of this phenomenon have proved that major events are triggered on preexisting major discontinuities, forced to slip by stress changes induced by water level fluctuations and/or pore-pressure changes in the rock mass in the vicinity of reservoirs. Song Tranh 2 is an artificial water reservoir located in Central Vietnam. Its main goal is back up the water for hydropower plant. High seismic activity has been observed in this area since the reservoir was first filled in 2011. The relation between water level and seismic activity in the Song Tranh area is complex, and the lack of clear correlation between water level and seismic activity has led to the conclusion that ongoing STR2 seismic activity is an example of the delayed response type of RTS. However, the first phase of the activity observed after impoundment has been deemed a rapid response type. In this work, we proved that the seismicity recorded between 2013 and 2016 manifested seasonal trends related to water level changes during wet and dry seasons. The response of activity and its delay with respect to water level changes suggest that the main triggering factor is pore pressure change due to the significant water level changes observed. A stress orientation difference between low and high water periods is also revealed. The findings indicate that water load and related pore pressure changes influence seismic activity and stress orientation in this area.</p><p>This work was partially supported by research project no. 2017/27/B/ST10/01267, funded by the National Science Centre, Poland, under agreement no. UMO-2017/27/B/ST10/01267.</p>

Download Full-text

The influence of long- and short-term volcanic strain on aquifer pressure: a case study from Soufrière Hills Volcano, Montserrat (W.I.)

Geophysical Journal International ◽

10.1093/gji/ggaa354 ◽

2020 ◽

Vol 223 (2) ◽

pp. 1288-1303

Author(s):

K Strehlow ◽

J Gottsmann ◽

A Rust ◽

S Hautmann ◽

B Hemmings

Keyword(s):

Water Level ◽

Pore Pressure ◽

Crustal Deformation ◽

Water Levels ◽

Short Term ◽

Soufriere Hills Volcano ◽

Soufrière Hills Volcano ◽

Water Level Changes ◽

Soufriere Hills

Summary Aquifers are poroelastic bodies that respond to strain by changes in pore pressure. Crustal deformation due to volcanic processes induces pore pressure variations that are mirrored in well water levels. Here, we investigate water level changes in the Belham valley on Montserrat over the course of 2 yr (2004–2006). Using finite element analysis, we simulate crustal deformation due to different volcanic strain sources and the dynamic poroelastic aquifer response. While some additional hydrological drivers cannot be excluded, we suggest that a poroelastic strain response of the aquifer system in the Belham valley is a possible explanation for the observed water level changes. According to our simulations, the shallow Belham aquifer responds to a steadily increasing sediment load due to repeated lahar sedimentation in the valley with rising aquifer pressures. A wholesale dome collapse in May 2006 on the other hand induced dilatational strain and thereby a short-term water level drop in a deeper-seated aquifer, which caused groundwater leakage from the Belham aquifer and thereby induced a delayed water level fall in the wells. The system thus responded to both gradual and rapid transient strain associated with the eruption of Soufrière Hills Volcano (Montserrat). This case study gives field evidence for theoretical predictions on volcanic drivers behind hydrological transients, demonstrating the potential of hydrological data for volcano monitoring. Interrogation of such data can provide valuable constraints on stress evolution in volcanic systems and therefore complement other monitoring systems. The presented models and inferred results are conceptually applicable to volcanic areas worldwide.

Download Full-text