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Your search keyword '"Braunmiller, J."' showing total 8 results
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8 results on '"Braunmiller, J."'

1. Training the Next Generation of Seismologists: Delivering Research-Grade Software Education for Cloud and HPC Computing through Diverse Training Modalities

Author

Denolle, M., Tape, C., Bozdağ, E., Wang, Y., Waldhauser, F., Gabriel, A. A., Braunmiller, J., Chow, B., Ding, L., Feng, K. F., Ghosh, A., Groebner, N., Gupta, A., Krauss, Z., McPherson, A., Nagaso, M., Niu, Z., Ni, Y., Orsvuran, R. \", Pavlis, G., Rodriguez-Cardozo, F., Sawi, T., Schliwa, N., Schneller, D., Shi, Q., Thurin, J., Wang, C., Wang, K., Wong, J. W. C., Wolf, S., and Yuan, C.

Subjects
Physics - Geophysics
Abstract

With the rise of data volume and computing power, seismological research requires more advanced skills in data processing, numerical methods, and parallel computing. We present the experience of conducting training workshops over various forms of delivery to support the adoption of large-scale High-Performance Computing and Cloud computing to advance seismological research. The seismological foci were on earthquake source parameter estimation in catalogs, forward and adjoint wavefield simulations in 2 and 3 dimensions at local, regional, and global scales, earthquake dynamics, ambient noise seismology, and machine learning. This contribution describes the series of workshops, the learning outcomes of the participants, and lessons learned by the instructors. Our curriculum was grounded on open and reproducible science, large-scale scientific computing and data mining, and computing infrastructure (access and usage) for HPC and the cloud. We also describe the types of teaching materials that have proven beneficial to the instruction and the sustainability of the program. We propose guidelines to deliver future workshops on these topics.

Published
2024

3. Homogeneous moment-magnitude calibration in Switzerland

Author

Braunmiller, J., Deichmann, N., Giardini, D., Wiemer, S., and Grp, S.

Subjects
Calibration (statistics), Surface wave magnitude, Moment magnitude scale, Induced seismicity, law.invention, Richter magnitude scale, Geophysics, Geochemistry and Petrology, Homogeneous, law, Seismic moment, Seismogram, Geology, Seismology
Abstract

An earthquake catalog containing a uniform size estimate is important for long-term seismic hazard assessment in regions of low-to-moderate seismicity. During the update of the Earthquake Catalog of Switzerland (ECOS), we performed regression analyses to convert all earthquake size information in ECOS to physically meaningful moment magnitude M-w. For 34 events in and near Switzerland, we determined seismic moment (thus Mw) by regional waveform inversion. Independent Mw estimates for the same events do not exist; however, Mw from European-Mediterranean events, obtained in the same way, agree with M, from Harvard CMT solutions. All other size estimates, M-L, M-D, m(b), M-S, and intensities, are calibrated relative to these 34 events. Teleseismic M-S and m(b) from international data centers are directly regressed against M-w. Most observations in ECOS consist of local magnitudes (ML, MD) and intensities. For local magnitudes, we first calibrated the Swiss Seismological Service's M-L. Then we calibrated magnitudes from observatories in neighboring countries (France, Germany, Italy) using only events in the border region (e.g., France-Switzerland). Modern instrumental records exist only since the mid-1970s. We calibrated the macroseismic dataset, which represents by far the largest period in the catalog, by determining surface wave magnitude M-S for stronger twentieth century Swiss earthquakes from analog seismograms. These M-S, which were converted to M-w, connect intensities and M-w. After calibration, all 20,300 events in ECOS have a unified M-w, including a class-type uncertainty estimate based on the original magnitude scale. ECOS covers the period 250-2001, from 44 degrees N to 51 degrees N and 4 degrees E to 13 degrees E. The largest event in ECOS is the 1356 M-w 6.9 Basle earthquake.

Published
2005

4. Earthquakes in Switzerland and surrounding regions during 2001

Author

Deichmann, N., Baer, M., Braunmiller, J., Dolfin, D.B., Bay, F., Bernardi, F., Delouis, B., Fah, D., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Abstract

Eclogae Geologicae Helvetiae, v. 95, n. 2, p. 249-262, 2002; International audience

Published
2002

5. The 7 May 2001 induced seismic event in the Ekofisk oil field, North Sea

Author

Ottemoller, L., Nielsen, H.H., Atakan, K., Braunmiller, J., Havskov, J., Ottemoller, L., Nielsen, H.H., Atakan, K., Braunmiller, J., and Havskov, J.

Abstract

A moderate size seismic event on 7 May 2001 was strongly felt on platforms in the Ekofisk oil field, in the southern North Sea, but did not cause damage to platforms or wells. We combined near- and far-field observations to develop a consistent source model and to determine whether the event was induced. Seismic data placed the epicenter inside the Ekofisk field and suggested a shallow source depth based on spectral and moment tensor analysis. GPS data from the Ekofisk platforms displayed permanent vertical and horizontal movement due to the event. A topographic bulge in the sea bottom, revealed by differential bathymetry data, and overpressure in the overburden in the northeastern part of the field, detected only after the event, had been caused by unintentional water injection that started in 1999. The injection pressure and rate were sufficient to raise the overburden. Pressure gauge and compaction data ruled out that the event occurred at reservoir level, which was further supported by unaffected production rates and absence of well failure. We therefore conclude that the event occurred in the overburden, at less than 3 km depth. Initially, this appeared unlikely on account of very low shear strength of the overburden clay-rich shale and mud rocks. The seismic event was induced owing to stress changes caused by water injection. The event possibly initiated on the northern flank of the field near the water injector and may have involved flexure of the overburden into the depression bowl in the rest of the field. Moment tensor analysis is consistent with a pure double-couple source. We suggest that slip occurred on the near-horizontal rather than along the near-vertical nodal plane. Stress drop was low, and owing to the low overburden shear strength, the event released less energy than a typical stress drop event with similar source dimensions.

Published
2005

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