Manoochehr Shirzaei

Predictability of hydraulic head changes and characterization of aquifer‐system and fault properties from InSAR‐derived ground deformation

We evaluate the benefits of space-derived ground deformation measurements for basin-wide characterization of aquifer-system properties and groundwater levels. We use Interferometric Synthetic Aperture Radar (InSAR) time series analysis of ERS, Envisat, and ALOS SAR data to resolve 1992–2011 ground deformation in the Santa Clara Valley, California. T-mode principal component analysis successfully isolates temporally variable deformation patterns embedded in the multidecadal time series. The data reveal uplift at 0.4 cm/yr between 1992 and 2000 and < 0.1 cm/yr during 2000–2011, illustrating the end of the aquifer-systems poroelastic rebound following recovery of hydraulic heads after the 1960s low stand. In addition, seasonal elastic deformation with amplitude of up to 3 cm, in phase with head fluctuations, is observed over the confined aquifer sharply partitioned by the Quaternary Silver Creek Fault (SCF). Integration of this deformation with hydraulic head data enables characterization of the aquifer-system storativity and elastic skeletal specific storage. Modeling of the deformation partitioning across the SCF constrains the faults last tectonic activity, hydraulic conductivity, and material composition. The SCF likely cuts the shallow confining clays and was last active since ~140 ka, it has a horizontal hydraulic conductivity several orders of magnitude lower than the surrounding aquifer-system, and is likely composed of clays, making it an effective barrier to across-fault fluid flow. Finally, we show that after a period of calibration, InSAR can be used to characterize basin-wide water level changes without well measurements with an accuracy of 70%, which demonstrates that it provides useful data for groundwater management.

Estimating the Effect of Satellite Orbital Error Using Wavelet-Based Robust Regression Applied to InSAR Deformation Data

Interferometric synthetic aperture radar data are often obtained on the basis of repeated satellite acquisitions. Errors in the satellite orbit determination, however, propagate to the data analysis and may even entirely obscure the interpretation. Many approaches have been developed to correct the effect of orbital error, which sometimes may even distort the signal. Phase contributions due to other sources, such as surface deformation, atmospheric delay, digital elevation model error, and noise, may reduce the accuracy of the orbital error estimation. Therefore, a more sophisticated approach for estimating the effect of orbital errors is required. In this paper, wavelet multiresolution analysis is employed to distinguish between the effects of orbital errors and other components (e.g., deformation signal). Next, a robust regression approach is applied to estimate the effect of orbit errors as a ramp. After describing the concept of this approach, we present a validation test using a synthetic data set. As in a real case study, the method is applied to an interferogram that was formed over the Tehran area in northern Iran. The validation test demonstrates that the orbital ramp can be estimated with a precision of 3 mm. Thus, a similar precision may be obtained in real cases such as the examined data set from over the Tehran area.

Surface uplift and time-dependent seismic hazard due to fluid injection in eastern Texas.

Observations that unequivocally link seismicity and wastewater injection are scarce. Here we show that wastewater injection in eastern Texas causes uplift, detectable in radar interferometric data up to >8 kilometers from the wells. Using measurements of uplift, reported injection data, and a poroelastic model, we computed the crustal strain and pore pressure. We infer that an increase of >1 megapascal in pore pressure in rocks with low compressibility triggers earthquakes, including the 4.8–moment magnitude event that occurred on 17 May 2012, the largest earthquake recorded in eastern Texas. Seismic activity increased even while injection rates declined, owing to diffusion of pore pressure from earlier periods with higher injection rates. Induced seismicity potential is suppressed where tight confining formations prevent pore pressure from propagating into crystalline basement rocks.

A Wavelet-Based Multitemporal DInSAR Algorithm for Monitoring Ground Surface Motion

I present a multitemporal algorithm with an improved filtering scheme compared with earlier works that combines and inverts a large set of unwrapped interferograms to generate an accurate time series of the surface motion. This method statistically analyzes the interferometric phase noise to identify stable pixels. Then, it applies an iterative 2-D sparse phase unwrapping operator and low-pass filter to each interferogram to obtain reliable absolute phase changes. Moreover, it uses a re-weighted least squares approach to robustly estimate the time series of the surface motion, which is followed by a temporal low-pass filter that reduces the effects of atmospheric delay. During various stages of the analysis, this approach applies a variety of sophisticated wavelet-based filters to estimate the interferometric phase noise and to reduce the effects of systematic and random artefacts, such as spatially correlated and temporally uncorrelated components of the atmospheric delay, and the digital elevation model and orbital errors. To demonstrate the capability of this method for accurately measuring nonlinear surface motions, I analyze a large set of SAR data acquired by the ENVISAT satellite from 2003 through 2010 over the south flank of the Kilauea volcano, Hawaii. The validation test shows that my approach is able to retrieve the surface displacement with an average accuracy of 6.5 mm.

Stress transfer in the Lazufre volcanic area, central Andes

eruptive centers situated in an area larger than 1800 km 2 and (2) a small-scale uplift located at Lastarria volcano, which is the only volcano to show strong fumarolic activity in decades, with most of the clear deformation apparently not observed before 2000. Both the large and small uplift signals can be explained by magmatic or hydrothermal sources located at about 13 km and 1 km deep, respectively. To test a possible relationship, we use numerical modeling and estimate that the depth inflating source increased the tensile stress close to the shallow source. We discuss how the deep inflating source may have disturbed the shallow one and triggered the observed deformation at Lastarria. Citation: Ruch, J., A. Manconi, G. Zeni, G. Solaro, A. Pepe, M. Shirzaei, T. R. Walter, and R. Lanari (2009), Stress transfer in the Lazufre volcanic area, central Andes, Geophys. Res. Lett., 36, L22303, doi:10.1029/2009GL041276.

Deep and shallow sources for the Lusi mud eruption revealed by surface deformation

The Lusi mud eruption, in East Java, Indonesia, began in May 2006 and continues to the present. Previous analyses of surface deformation data suggested an exponential decay of the pressure in the mud source but did not constrain the location, geometry, and evolution of the possible source(s) of the erupting mud and fluids. To map the surface deformation, we employ multitemporal interferometric synthetic aperture radar and analyze a well-populated L-band data set acquired by the Advanced Land Observing Satellite (ALOS) between May 2006 and April 2011. We then apply a time-dependent inverse modeling scheme. Volume changes occur in two regions beneath Lusi, at 0.3–2.0 km and 3.5–4.75 km depth. The cumulative volume change within the shallow source is ~2–3 times larger than that of the deep source. The observation and model suggest that a shallow source plays a key role by supplying the erupting mud, but that additional fluids do ascend from depths >4 km on eruptive timescales.

Increased stream discharge after the 3 September 2016 Mw 5.8 Pawnee, Oklahoma earthquake

Earthquakes influence hydrogeological processes and properties in Earths crust, some of which affect surface waters. We document increased discharge in a stream after the 3 September 2016 Mw 5.8 earthquake near Pawnee, Oklahoma, an event likely induced by underground wastewater disposal. Discharge increased by an order of magnitude and remained elevated until the change was obscured by rain 1 week later. Given the earthquake magnitude and distance from the stream, by comparison with previous examples of responses to earthquakes, increased discharge after this earthquake is expected. While the mechanism increasing discharge cannot be confirmed, the observations require changes in physical properties of the subsurface. Fluid injection may thus influence hydrogeological properties of shallow groundwater systems and aquifers indirectly by inducing seismicity, if the induced seismic events are large enough.

Spatiotemporal characterization of land subsidence and uplift in Phoenix using InSAR time series and wavelet transforms

The effects of land subsidence pose a significant hazard to the environment and infrastructure in the arid, alluvial basins of Phoenix, Arizona. Improving our understanding of the source and mechanisms of subsidence is important for planning and risk management. Here we employ multitemporal interferometric analysis of large synthetic aperture radar data sets acquired by ERS and Envisat satellites to investigate ground deformation. The ERS data sets from 1992 to 1996 and Envisat, 2003–2010, are used to generate line of sight (LOS) time series and velocities in both the ascending and descending tracks. The general deformation pattern is consistent among data sets and is characterized by three zones of subsidence and a broad zone of uplift. The multitrack Envisat LOS time series of surface deformation are inverted to obtain spatiotemporal maps of the vertical and horizontal deformation fields. We use observation wells to provide an in situ, independent data set of hydraulic head levels. Then we analyze vertical interferometric synthetic aperture radar and hydraulic head level time series using continuous wavelet transform to separate periodic signal components and the long-term trend. The isolated signal components are used to estimate the elastic storage coefficient, the inelastic skeletal storage coefficient, and compaction time constants. Together these parameters describe the storage response of an aquifer system to changes in hydraulic head and surface elevation. Understanding aquifer parameters is useful for the ongoing management of groundwater resources.

A seamless multitrack multitemporal InSAR algorithm

The zones of overlap between adjacent Synthetic Aperture Radar (SAR) satellite tracks are illuminated twice more frequently than elsewhere in the SAR scene. Here, an alternative approach is presented to combine the overlapping segments of SAR images acquired at adjacent tracks and generate accurate and high spatiotemporal resolution map of the surface deformation field. To this end, a new approach is developed to unify the datums. Effects due to the difference in look angle between two overlapping tracks and atmospheric delay are estimated and removed using Kalman and wavelet-based filters. This approach is first tested at Hawaii Island, where tracks 200 and 429 of Envisat C-band satellite overlap over the Kilauea south flank. The obtained time series improves the temporal sampling rate by a factor of two and comparison with GPS time series demonstrates that the presented method accurately measures the nonlinear deformation field. The advantages of this method are further demonstrated by combining SAR data sets acquired by Envisat C-band and ALOS L-band satellites over the San Francisco Bay Area, California. The validation test shows that the seamless combination of C-band and L-band time series accurately measures the surface deformation at higher resolution.

Slow and Go: Pulsing slip rates on the creeping section of the San Andreas Fault

Rising and falling slip rates on the creeping section of the San Andreas Fault have been inferred from variations of recurrence intervals of characteristically repeating microearthquakes, but this observation has not previously been confirmed using modern geodetic data. Here we report on observations of this “pulsing” slip obtained from advanced multitemporal interferometric synthetic aperture radar (InSAR) data, confirmed using continuous GPS sites of the Plate Boundary Observatory. The surface deformation time series show a strong correlation to the previously documented slip rate variations derived from repeating earthquakes on the fault interface, at various spatial and temporal scales. Time series and spectral analyses of repeating earthquake and InSAR data reveal a quasiperiodic pulsing with a roughly 2 year period along some sections of the fault, with the earthquakes on the fault interface lagging behind the far-field deformation by about 6 months. This suggests a temporal delay between the pulsing crustal strain generated by deep-seated shear and the time-variable slip on the shallow fault interface, and that at least in some places this process may be cyclical. There exist potential impacts for time-dependent seismic hazard forecasting in California and, as it becomes better validated in the richly instrumented natural laboratory of the central San Andreas Fault, the process used here will be even more helpful in characterizing hazard and fault zone rheology in areas without Californias geodetic infrastructure.