Evidence for a meteoritic origin of the September 15, 2007, Carancas crater

On September 15th, 2007, around 11:45 local time in Peru, near the Bolivian border, the atmospheric entry of a meteoroid produced bright lights in the sky and intense detonations. Soon after, a crater was discovered south of Lake Titicaca. These events have been detected by the Bolivian seismic network and two infrasound arrays operating for the Comprehensive Nuclear-Test-Ban Treaty Organization, situated at about 80 and 1620 km from the crater. The localization and origin time computed with the seismic records are consistent with the reported impact. The entry elevation and azimuthal angles of the trajectory are estimated from the observed signal time sequences and backazimuths. From the crater diameter and the airwave amplitudes, the kinetic energy, mass and explosive energy are calculated. Using the estimated velocity of the meteoroid and similarity criteria between orbital elements, an association with possible parent asteroids is attempted. The favorable setting of this event provides a unique opportunity to evaluate physical and kinematic parameters of the object that generated the first actual terrestrial meteorite impact seismically recorded

Characterization of regional and local scattering effects from small-aperture seismic array recordings

Journal of Seismology, v. 9, n. 2, p. 137-149, 2005. http://dx.doi.org/10.1007/s10950-005-8234-1International audienc

Automatic processing of seismic events recorded on a mini-array Signal analysis combined with neural networks

We present a new method for automatic processing of mini-array records of regional events. It is based on a comprehensive analysis of the cross-correlation functions. This leads to a set of time-delays used to compute the azimuth and velocity of the travelling wave only in case of consisteney of the time-delay set. The second step takes into account the time-frequency representations of these wave parameters to identify each regional wave using a neural network. The resulting standard error on azimuth is 3° and the relative error on distance is less than 20%

Automatic processing of seismic events recorded on a mini-array Signal analysis combined with neural networks

We present a new method for automatic processing of mini-array records of regional events. It is based on a comprehensive analysis of the cross-correlation functions. This leads to a set of time-delays used to compute the azimuth and velocity of the travelling wave only in case of consisteney of the time-delay set. The second step takes into account the time-frequency representations of these wave parameters to identify each regional wave using a neural network. The resulting standard error on azimuth is 3° and the relative error on distance is less than 20%

OLS vs WLS for DOA Estimation Based on TDOA Estimates: Application to Infrasonic Signals

International audience<p>Monitoring of infrasound sources has received significant attention during the last decades for many civil and scientificapplications. The two main problems are the detection of the signal on the one hand and the estimation of wave parameters. Forazimuth estimation, the commonly used approach consists of estimating at first the time difference of arrival (TDOA) betweenany two sensors, using cross-correlation maximization. Then, assuming a plane wave propagation, it is easy to prove that theseTDOA estimates depend linearly of two ancillary variables which are in a one-to-one mapping with the azimuth parameter. Usualestimation of the ancillary variables is made from the TDOA estimates, using an ordinary least square (OLS) criterion, implyingthat the estimation errors on the TDOAs may be considered as uncorrelated. Unfortunately, it is known that this property is nottrue. Therefore the estimator of the weighted least squares (WLS) must be preferred. In this paper, we determine the analyticalexpression of the correlation matrix of TDOA estimators based on the signal-to-noise ratio (SNR) of each sensor and then, usingthe sensor locations, derive the covariance matrices of OLS and WLS estimators. We also propose a procedure to estimate theSNR from the the observed signals. The main interest of our study is to show that, theoretically, the proposed WLS approachworks always better, in terms of confidence ellipses, than the OLS except if the SNRs on each sensor are equal. Finally, numericalresults in the infrasonic context are presented.</p

Modelling Local Seismograms of French Nuclear Tests In Taourirt Tan Afella Massif, Hoggar, Algeria

Geophysical Journal International, vol. 199, n°3, pp. 964 - 974, 1994International audienc

Urinary incontinence in pregnant women and its relation with socio-demographic variables and quality of life

OBJECTIVE: To investigate the occurrence of urinary incontinency (UI) in pregnantwomen and its relationship with socio-demographic variables and quality of life. METHODS: A descriptive cross-sectional multicenter study was conducted to investigate 495 women using the International Consultation on Incontinence Questionnaire - Short Form (ICIQ-SF). The survey was conducted on the same day of delivery, with the volunteers still in the maternity ward. Statistical analysis of the comparison between groups 1 (incontinence) and 2 (continent) was done using chi-square test for comparison of proportions of women with and without urinary incontinency and logistic regression analysis. RESULTS: From the total of 495 women studied, 352 (71%) reported having had UI during the last four weeks of pregnancy. Group 1 presented the ICIQ-SF median score of 11 (range 3- 21), considered as severe impact in quality of life. Logistic regression analysis showed that there was a closer relation between the self-report of UI with the following variables: level of education below 8 years (OR: 2.99; p < 0.001), black women (OR: 2.32; p= 0.005), women with more than 3 children (OR: 4.93; p < 0.001), obese (OR: 4.22; p < 0.001) and normal vaginal delivery (OR: 2.59; p < 0.001). CONCLUSION: The majority of pregnantwomen have UI, negatively affecting the quality of their lives