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Pasadena, CA, United States

Lemnitzer A.,University of | Massone L.M.,University of Chile | Skolnik D.A.,Kinemetrics Inc. | de la Llera Martin J.C.,University of Santiago de Chile | Wallace J.W.,University of California at Los Angeles
Engineering Structures | Year: 2014

Between March 13th and 28th 2010, a team of U.S. researchers, professionals, and local collaborators instrumented four reinforced concrete (RC) buildings in Santiago, Chile, to measure aftershock response data following the February 27, 2010 MW 8.8 earthquake. The selected buildings, designed according to NCh433.Of96 (similar to ACI 318-95), represent typical construction, e.g. moderate to high rise office buildings with large office space and inner core shear walls and mid-rise residential shear wall buildings. Two of the instrumented buildings were undamaged, whereas one building suffered only minor non-structural damage and the fourth building exhibited more significant structural damage such as column buckling and shear wall cracking. Instrumentation consisted mainly of uni-axial and tri-axial accelerometers as well as some displacement transducers. Records for several aftershocks were captured during a period of one month. Collected data were processed and system identification algorithms were used to determine dynamic building- and modeling parameters (e.g. building periods, acceleration amplification, inter-story drifts, building rocking and torsion, and assessment of diaphragm in-plane rigidity). A comparison between linear elastic models used in engineering practice and measured data was performed for one building. Information related to the instrumented buildings, data collected, and analytical results is presented, along with practical lessons learned conducting monitoring studies in the aftermath of this very strong earthquake. © 2014 Elsevier Ltd. Source

Roman D.C.,Carnegie Institution of Washington | Gardine M.D.,University of South Florida | Gardine M.D.,Kinemetrics Inc.
Earth and Planetary Science Letters | Year: 2013

Successful eruption forecasts are heavily dependent on the recognition of well-established patterns in volcano monitoring data. Therefore, it is critical to develop, in retrospect, an understanding of the physical basis for cases of abnormal precursory behavior, as the basis for (a) a complete understanding of the range of precursory signals that may be expected at a particular volcano and (b) development of new monitoring approaches to detect more subtle signals of the underlying processes responsible for common patterns of seismic unrest. Here, using a hybrid analysis of shear-wave splitting (SWS) and double-couple fault-plane solutions (FPS), we document the timing and nature of local stress field changes in the months to days preceding the 2009 eruption of Redoubt Volcano, Alaska, which was characterized by an abnormally long period of precursory low-frequency seismicity reflected in multiple escalations of alert levels prior to the eruption. We find that an approximately ~90° change in the polarization of fast S-wavelets (Φ) accompanied the earliest signs of seismic unrest in 2008 and continued through the eruption before diminishing in 2009. A similar change in the orientation of VT FPS occurred 18-48. h prior to the eruption onset on March 23, 2009, but almost two months after a strong increase in the rate of shallow VT earthquakes. Combined, our SWS and FPS results show the earliest-, and latest-known changes in seismic monitoring data, respectively, and are suggestive of a protracted period of slow magma ascent followed by a short period of rapidly increasing magma pressurization beneath the volcano. These results demonstrate the power of a combined stress-field analysis for clarifying the processes driving ambiguous seismic unrest at active volcanoes. © 2013 Elsevier B.V. Source

Pike W.T.,Imperial College London | Standley I.M.,Kinemetrics Inc. | Calcutt S.,University of Oxford
2013 Transducers and Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS and EUROSENSORS 2013 | Year: 2013

The design, fabrication and testing of a microseismometer for the InSight mission to Mars and described. Particular challenges include accommodation of Martian gravity while allowing testing on Earth and surviving the 2000g shock profile of the mission while maintaining a nano-g sensitivity. © 2013 IEEE. Source

Kinemetrics Inc. | Date: 2008-07-08

LAN (local operating network) hardware for connecting seismological instruments, computer hardware for operating computer software for configuring and managing seismological computer software for monitoring the operational status of a group of seismological instruments, computer software for collecting and processing data from a group of seismological instruments.

Kinemetrics Inc. | Date: 2008-07-08

Seismological instruments, strong motion accelerograph used in earthquake and seismic monitoring, Sensors for detecting seismic activity.

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