Abstract

This study investigates crustal thickness and properties within the Libyan region. Results obtained from 15 seismic stations belonging to the Libyan Center for Remote Sensing and Space Science are reported, in addition to 3 seismic stations publically available, using receiver functions. The results show crustal thicknesses ranging from 24 km to 36 km (with uncertainties ranging between ±0.10 km and ±0.90 km). More specifically, crustal thickness ranges from 32 km to 36 km in the southern portion of the Libyan territory then becomes thinner, between 24 km and 30 km, in the coastal areas of Libya and thinnest, between 24 km and 28 km, in the Sirt Basin. The observed high Vp/Vs value of 1.91 at one station located at the AS Sawda Volcanic Province in central Libya indicates the presence of either partial melt or an abnormally warm area. This finding suggests that magma reservoirs beneath the Libyan territory may still be partially molten and active, thereby posing significant earthquake and volcanic risks. The hypothesis of an active magma source is further demonstrated though the presence of asthenospheric upwelling and extension of the Sirt Basin. This study provides a new calculation of unconsolidated sediment layers by using the arrival time of the P to S converted phases. The results show sediments thicknesses of 0.4 km to 3.7 km, with the Vp/Vs values ranging from 2.2 to 4.8. The variations in crustal thickness throughout the region are correlated with surface elevation and Bouguer gravity anomalies, which suggest that they are isostatically compensated.

Department(s)

Mining and Nuclear Engineering

Comments

Data used in this study were obtained from two sources: (1) Libyan Center for Remote Sensing and Space Science (LCRSSS) and (2) the IRIS DMC. We are grateful to Y. Yu for assistance with data processing and S. Gao for helpful discussions and comments. We thank C. Reed for providing Bouguer gravity anomaly data for Figure 7b, as well as A. A. Elmelade for providing seismic data from the LCRSSS. We thank the Editors U. ten Brinkand and D. van Hinsbergen and two anonymous reviewers for their constructive comments that helped to improve an earlier version of the manuscript. We are grateful for support from the Benghazi University of Libya. Also, this study was partially supported by Mining Engineering Department, Missouri University of Science and Technology, Rolla, Missouri, USA. All the receiver functions used in the study can be found in the supporting information section. The RFs are in SAC (Seismic Analysis Codes) format. Also included in the supporting information section are a catalog of earthquakes used, as well as an H-plot for each of the stations.

Keywords and Phrases

Bouguer anomaly; Crustal thickness; Magma; Partial melting; Seismic velocity; Seismic wave; Tectonics; Volcano; Libyan Arab Jamahiriya; Sirte Basin; Libya; Partial melt; Receiver functions; Volcano tectonics

International Standard Serial Number (ISSN)

2169-9313

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2017 American Geophysical Union, All rights reserved.

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