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Session: Urban Seismology

Type: Oral

Date: 10/10/2024

Time: 12:15 PM

Room: Stanley Park Ballroom

Fiber Optic Seismology in Densely Populated Urban Areas Exposed to Seismic Hazard

DAS and other photonic sensing technologies have led to a rapidly expanding area of research utilizing existing telecommunication fibers for urban seismology. With the significant spatial extent of these deployments, one is able to use one fiber to study multiple aspects of urban seismic hazard, from monitoring seismicity on local faults, to producing subsurface velocity profiles in even the densest population centers. Here, we present a summary of recent DAS experiments in urban areas exposed to significant seismic hazard, including Athens and Santorini in Greece, and Istanbul in Türkiye.

Within these urban experiments, we tackle multiple aspects of seismic hazard. We utilize dispersion measurements derived from ambient noise to constrain shallow subsurface velocity structure and demonstrate this method in a pilot study in Bern, Switzerland, as well as in a more extensive deployment in Athens, Greece. Obtaining high-resolution velocity information in the top tens of meters of the subsurface can reveal structural heterogeneities relevant for construction and seismic hazard mitigation. The same workflow is applied in Istanbul, Türkiye, with the addition of 2D full-waveform inversion updates to refine the final model. Our Istanbul acquisition recorded many of the February 2023 Turkey–Syria earthquakes, and we are able to clearly see the seismic waves propagating in the data, as well as areas of local site amplification. Our field experiments also reveal numerous small, local earthquakes not contained in network catalogs. We have developed several methods for detecting and locating seismic events and compare our event catalogs to those of regional networks. In spite of fairly linear fiber configurations in Athens and Istanbul, we are able to locate many detected events. However, in the more geologically complex submarine environment off the island of Santorini, solving for event locations proves to be extremely challenging. Such observations may indicate limits on the potential usability of DAS in particularly complex environments.

Presenting Author: Krystyna

Additional Authors