Details

• Dr. Peter Eric Malin, GFZ German Research Centre for Geosciences, Potsdam, Alemanya & ASIR, Dallas, Texas, EUA
• Date: Oct, 1, 2015 12:00 am
• Place: Sala d’Actes del Institut de Ciències de la Terra Jaume Almera(ICTJA)
• Location: C/ Solé i Sabarís s/n, Barcelona
• Contact: >Maria José Jurado (ICTJA)

Abstract

In this presentation we describe the installation, operation, analysis, and interpretation of borehole geophysical observatories in a few urban and several non-urban settings.  For example, New Plymouth, Istanbul, Al Medina, and Auckland are built near or directly on potentially active volcanic and earthquake systems.  New Plymouth, on the island of Montserrat, was actually destroyed by the island’s active volcano. While not near any volcanoes, the city of Basel sits on a seismically active rift.  This city recently experienced a man-made tremor resulting from an attempt to create an engineered geothermal system.  In the US, it seems likely that the Raton coal bed methane production field in southern Colorado caused a M~5 event.  While not directly in a city, the latter event was large enough to raise national attention to the seismicity problems associated with fracking and deep well waste disposal. Similar concerns have also been raised about the seismicity caused by geothermal development at Puna, Hawaii.   In each case the local environmental conditions make it difficult to monitor these potential hazards – their geography, weather, or cultural noise present major obstacles to surface recording of earthquake data. Further, low levels of historical seismicity make detection and monitoring of the active fault we know underlie, for example, Auckland, particularly challenging.  In the case of Istanbul, the potential dangerous North Anatolian Fault lies just off shore, beneath the Sea of Marmara. In these circumstances, borehole geophysical monitoring may be the only technique available for keeping track of the small signals that might relate to any magmatic, tectonic, or man-made movements that might put these places at risk.  In the cases listed above, we have installed either borehole seismometers, or both borehole seismometers and 2 types of strainmeters. The data from these instruments have resulted in rapid accumulation of seismicity catalogues for both scientific and public purposes.