Seismic signature of the Azure Window collapse, Gozo, Central Mediterranean

Abstract

The Azure Window was the name given to an imposing natural arch on the northwestern coast of the island of Gozo, the second largest island of the Maltese archipelago, Central Mediterranean. The geomorphological feature, carved in the Lower Coralline Limestone formation, was an iconic landmark for Gozo. It was also well known internationally as one of the major tourist attractions of the island. On 8 March 2017, following a period of stormy conditions, the arch collapsed swiftly and completely, leaving no trace above water. The impact of the collapsed rockmass on the sea floor generated a seismic signal that was recorded on two stations of the Malta Seismic Network. In this article, we study the nature of this signal and what information may be deduced from it. We also compare it to another major rock collapse and a magnitude 3.0 earthquake that occurred 2 years earlier along the southeastern coastline of Malta.