ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
  • 12
    Publication Date: 2005-12-01
    Print ISSN: 0012-821X
    Electronic ISSN: 1385-013X
    Topics: Geosciences , Physics
    Published by Elsevier
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Publication Date: 2013-12-24
    Description: The California Integrated Seismic Network (CISN) is developing an earthquake early warning (EEW) demonstration system for the state of California. Within this CISN ShakeAlert project, three algorithms are being tested, one of which is the network-based Earthquake Alarm Systems (ElarmS) EEW system. Over the last three years, the ElarmS algorithms have undergone a large-scale reassessment and have been recoded to solve technological and methodological challenges. The improved algorithms in the new production-grade version of the ElarmS version 2 (referred to as ElarmS-2 or E2) code maximize the current seismic network's configuration, hardware, and software performance capabilities, improving both the speed of the early warning processing and the accuracy of the warnings. E2 is designed as a modular code and consists of a new event monitor module with an improved associator that allows for more rapid association with fewer triggers, while also adding several new alert filter checks that help minimize false alarms. Here, we outline the methodology and summarize the performance of this new online real-time system. The online performance from 2 October 2012 to 15 February 2013 shows, on average, ElarmS currently issues an alert 8.68+ or -3.73 s after the first P-wave detection for all events across California. This time is reduced by 2 s in regions with dense station instrumentation. Standard deviations of magnitude, origin time are 0.4 magnitude units, 1.2 s, and the median location errors is 3.8 km. E2 successfully detected 26 of 29 earthquakes (M (sub ANSS) 〉3.5) across California, while issuing two false alarms. E2 is now delivering alerts to ShakeAlert, which in turn distributes warnings to test users.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Publication Date: 2011-01-26
    Description: Lateral variation in crustal attenuation of California is calculated by inverting 25,330 synthetic Wood-Anderson amplitudes from the California Integrated Seismic Network (CISN) for site, source, and path effects. Two-dimensional attenuation (q or 1/Q) is derived from the path term, which is calculated via an iterative least-squares inversion that also solves for perturbations to the site and source terms. Source terms agree well with initial CISN M (sub L) s, and site terms agree well with a prior regression analysis; q ranges from low attenuation at 0.001 (Q=1000) to high attenuation at 0.015 (Q=66), with an average of 0.07 (Q=143). The average q is consistent with an amplitude decay function (logA (sub 0) ) for California when q is combined with a simple geometrical spreading rate. Attenuation in California is consistent with the tectonic structure of California, with low attenuation in the Sierra batholith and high attenuation at The Geysers, at Long Valley, and in the Salton trough possibly due to geothermal effects. Also, path terms are an order of magnitude smaller than site and source terms, suggesting that they are not as important in correcting for M (sub L) .
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Publication Date: 2011-12-01
    Description: Determining local magnitude (M (sub L) ) in a manner that is uniform and internally consistent for earthquakes throughout California and the vicinity is an important component of the California Integrated Seismic Network (CISN). We present a new local magnitude attenuation function and corresponding station adjustments that are valid throughout California. The new attenuation function is an analytic function of the radial hypocentral distance between 1 and 500 km. Associated station adjustments are also available for 1185 horizontal seismometer and accelerometer channels from five seismic networks operating in California. The new attenuation function and adjustments provide several advantages to CISN. They allow a more robust M (sub L) computation, the M (sub L) s are more consistent between northern and southern California than they have been in the past, and because adjustments are now available for more station-network-channel-location codes (SNCLs), M (sub L) s can be computed for small earthquakes in more locations than was previously possible. In addition to describing our method for calibrating the new CISN M (sub L) , we also present a tool for adding adjustments for new or upgraded stations.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Publication Date: 2020-02-12
    Description: In the present paper we describe the on-land field operations integrated in the TOMO-ETNA experiment carried out in June-November 2014 at Mt. Etna volcano and surrounding areas. This terrestrial campaign consists in the deployment of 90 short-period portable three-component seismic stations, 17 Broadband seismometers and the coordination with 133 permanent seismic station belonging to Italy’s Istituto Nazionale di Geofisica e Vulcanologia (INGV). This temporary seismic network recorded active and passive seismic sources. Active seismic sources were generated by an array of air-guns mounted in the Spanish oceanographic vessel “Sarmiento de Gamboa” with a power capacity of up to 5200 cubic inches. In total more than 26,000 shots were fired and more than 450 local and regional earthquakes were recorded. We describe the whole technical procedure followed to guarantee the success of this complex seismic experiment. We started with the description of the location of the potential safety places to deploy the portable network and the products derived from this search (a large document including full characterization of the sites, owners and indication of how to arrive to them). A full technical description of the seismometers and seismic sources is presented. We show how the portable seismic network was deployed, maintained and recovered in different stages. The large international collaboration of this experiment is reflected in the participation of more than 75 researchers, technicians and students from different institutions and countries in the on-land activities. The main objectives of the experiment were achieved with great success.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Publication Date: 2020-11-12
    Description: The number of tornillo events has recently increased at the Vulcano Island, Italy. While only 15 tornillos were recorded during 2004–2006, 584 events occurred in 2007–2008. They were located just below La Fossa Crater at depths ranging between 0.1 and 1 km b.s.l. During two intervals in 2007–2008 increases in the number of tornillos took place at the same time as temperature and geochemical anomalies were observed. The spectral content of the tornillos, generally characterized by one–two dominant spectral peaks near 6 and 10 Hz, varied over time, with changes also noted in the quality factors. The simplest source mechanism proposed for tornillos is the free eigenvibration of a fluid volume within a crack or a conduit. Based on this model, we propose a causal relationship between the temperature and geochemical anomalies and the increases in numbers of tornillos. As the amount of hydrothermal fluids increases during the anomalies, the upward flux of fluids grows. The consequent changes in the pressure, temperature and dynamics of the system of cracks and conduits result in the generation of tornillos. Based on the fluid-filled crack/conduit model, the shallow depths of the sources and the values of the quality factors, the fluid within the resonant crack/conduit was inferred to be an ash–gas or water droplet–gas mixture. Moreover, the observed variations in the wavefield can be caused by small changes in the location of the source, in the source mechanism, or in the medium in between the source and the seismic station. Finally, another peculiar feature of tornillos is the amplitude modulation that can be explained as a result of a beating phenomenon.
    Description: Published
    Description: 377-393
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Tornillos ; Vulcano Island ; Hydrothermal system ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Publication Date: 2017-04-04
    Description: Almost 50,000 long period (LP) events were recorded at Mt. Etna from November 2003 to May 2006. We analysed these events, as well as very long period (VLP) events which were associated with some of them. During some intervals the spectral and wavefield features of LP events remained steady, with significant changes occurring between the intervals. Based on the times of the changes, we distinguish five different sub-periods. In particular, during sub-period III (June–November 2005) the wavefield at the stations nearest to the summit area was composed of P waves. Locations for 150 LP events occurring in sub-period III, determined using radial semblance, changed, at the same time as the events' spectral features changed. It was during this sub-period that many of the LP events were associated with VLP events. Based on similarity of the waveforms, we distinguished two families of VLP events, with gradually evolving waveforms. The two families are located in slightly different places, but near the sources of the LP events. The change between the families occurred at the same time as the spectra of the LP events changed. Finally the source of the VLP events was investigated by performing complete waveform moment tensor inversion of stacks of the two families. Synthetic Green's functions for the full moment tensor were calculated for a homogeneous halfspace. For both families, the source region with the highest variance reduction lies approximately beneath the active craters, at 500 m below the altitudes of the stations. The solutions for both families are very similar with sources that are between 60 and 70% isotropic. Attempts to determine deviatoric moment tensors produced consistently poorer fits. The remaining energy is poorly constrained and is likely to be noise. In conclusion, these results highlight changes in the LP and VLP events at Mt. Etna over time, and the causal relationship between them.
    Description: Published
    Description: 227-249
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; LP events ; VLP events ; moment tensor ; source location ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Publication Date: 2019-11-04
    Description: During the Proyecto de Investigaciòn Sismològica de la Cordillera Occidental (PISCO '94) in the Atacama desert of Northern Chile, a continuously recording broadband seismic station was installed to the NW of the currently active volcano, Lascar. For the month of April, 1994, an additional network of three, short period, three-component stations was deployed around the volcano to help discriminate its seismic signals from other local seismicity. During the deployment, the volcanic activity at Lascar appeared to be limited mainly to the emission of steam and SO2. Tremor from Lascar is a random, «rapid-fire» series of events with a wide range of amplitudes and a quasi-fractal structure. The tremor is generated by an ensemble of independent elementary sources clustered in the volcanic edifice. In the short-term, the excitation of the sources fluctuates strongly, while the long-term power spectrum is very stationary.
    Description: JCR Journal
    Description: open
    Keywords: volcano seismology ; volcanic tremor ; rapid-fire events ; Lascar volcano ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 2523390 bytes
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Publication Date: 2019-11-04
    Description: he M 7.4 Landers earthquake triggered widespread seismicity in the Western U.S. Because the transient dynamic stresses induced at regional distances by the Landers surface waves are much larger than the expected static stresses, the magnitude and the characteristics of the dynamic stresses may bear upon the earthquake triggering mechanism. The Landers earthquake was recorded on the UPSAR array, a group of 14 triaxial accelerometers located within a 1-square-km region 10 km southwest of the town of Parkfield, California, 412 km northwest of the Landers epicenter. We used a standard geodetic inversion procedure to determine the surface strain and stress tensors as functions of time from the observed dynamic displacements. Peak dynamic strains and stresses at the Earth's surface are about 7 microstrain and 0.035 MPa, respectively, and they have a flat amplitude spectrum between 2 s and 15 s period. These stresses agree well with stresses predicted from a simple rule of thumb based upon the ground velocity spectrum observed at a single station. Peak stresses ranged from about 0.035 MPa at the surface to about 0.12 MPa between 2 and 14 km depth, with the sharp increase of stress away from the surface resulting from the rapid increase of rigidity with depth and from the influence of surface wave mode shapes. Comparison of Landers-induced static and dynamic stresses at the hypocenter of the Big Bear aftershock provides a clear example that faults are stronger on time scales of tens of seconds than on time scales of hours or longer.
    Description: JCR Journal
    Description: open
    Keywords: stress ; surface waves ; Parkfield ; Landers earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 4977205 bytes
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...