Error estimation in multitemporal InSAR deformation time series, with application to Lanzarote, Canary Islands

Interferometric Synthetic Aperture Radar (InSAR) is a reliable technique for measuring crustal deformation. However, despite its long application in geophysical problems, its error estimation has been largely overlooked. Currently, the largest problem with InSAR is still the atmospheric propagation errors, which is why multitemporal interferometric techniques have been successfully developed using a series of interferograms. However, none of the standard multitemporal interferometric techniques, namely PS or SB (Persistent Scatterers and Small Baselines, respectively) provide an estimate of their precision. Here, we present a method to compute reliable estimates of the precision of the deformation time series. We implement it for the SB multitemporal interferometric technique (a favorable technique for natural terrains, the most usual target of geophysical applications). We describe the method that uses a properly weighted scheme that allows us to compute estimates for all interferogram pixels, enhanced by a Montecarlo resampling technique that properly propagates the interferogram errors (variance-covariances) into the unknown parameters (estimated errors for the displacements). We apply the multitemporal error estimation method to Lanzarote Island (Canary Islands), where no active magmatic activity has been reported in the last decades. We detect deformation around Timanfaya volcano (lengthening of line-of-sight ∼ subsidence), where the last eruption in 1730–1736 occurred. Deformation closely follows the surface temperature anomalies indicating that magma crystallization (cooling and contraction) of the 300-year shallow magmatic body under Timanfaya volcano is still ongoing.Peer reviewe

Comparison of MIF levels in patients after ROSC with those obtained in patients after cardiac surgery.

<p>Values are represented as mean ±<i>SD</i> at predefined timepoints after succesful CPR. MIF levels of healthy volunteers are additionally depicted at the time point “admission". * p<0.007 vs. baseline. § p<0.007 vs patients after ROSC. # p<0.007 vs. group of healthy volunteers.</p

MIF serum levels in survivors and non-survivors.

<p>Values are represented as mean ±<i>SD</i> at predefined timepoints after succesful CPR.</p

Comparison of time course of inflammatory reaction in patients after OHCA and after cardiac surgery as assessed by the serum levels of procalcitonin (µg/l).

<p>IQR=interquartile range [IQR].</p><p>n.a.=not available.</p><p>Results of the overall RMANOVA: p=0.71 (group); p=0.02 (time); p=0.59 (interaction).</p

Serum levels of MIF, TNF-α, IL-6 and CRP after admission to the ICU and 6, 24, 72 and 120 hours later.

<p>* p<0.007 vs. baseline.</p

Baseline characteristics for patients after cardiac surgery.

<p>n=absolute number; (%)=percentage of the whole; IQR=interquartile range; SD=standard deviation.</p><p>CABG=coronary artery bypass graft; CPB=cardiopulmonary bypass.</p

MIF serum levels in patients who recieved MTH in comparison with normothermically treated patients.

<p>Values are represented as mean ±<i>SD</i> at predefined timepoints after succesful CPR.</p

Baseline characteristics for patients after ROSC.

<p>n=absolute number; (%)=percentage of the whole; IQR=interquartile range; SD=standard deviation.</p><p>VF=ventricular fibrillation; CPR=cardiopulmonary resuscitation; CPC=cerebral performance categories.</p

Patient baseline characteristics and data on surgery in the two groups.

<p>Data are presented as median (range) (not normally distributed data), as mean ± SD (normally distributed data) or as</p><p>absolute numbers (with the percentage (%) of the whole). * p<0.05</p><p>[95% CI]  =  95% Confidence intervall on the mean</p><p>CABG  =  coronary artery bypass grafting; CPB  =  cardiopulmonary bypass, MI  =  myocardial infarction, PRBC = packed red blood cells.</p

Receiver operating characteristic curve (all patients).

<p>Receiver operating characteristic curve for the significance of postoperative (admission to ICU) selenium, GPx, ADMA and CK-MB concentrations in all patients to predict the development of organ dysfunction in the postoperative period. AUC, area under the receiver operating curve.</p