The United States Geological Survey recorded a Magnitude 4.6 Earthquake at a depth of72.9 km about 68 km to the southwest of Lombok Island in Indonesia at about 12.25 pm local time (about 4.25 am GMT) on Sunday 12 February 2017. The event was felt across most of Bali and Lombok islands, but there are no reports of any damage or injuries.
The approximate location of the12 February 2017 Indonesia Earthquake. USGS.
The Indo-Australian Plate, which underlies the Indian Ocean to the south of Java, Bali and Lombok, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies the islands and neighbouring Sumatra, along the Sunda Trench, passing under the islands, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fuelling the volcanoes of Java and neighbouring islands.
Subduction along the Sunda Trench beneath Java, Bali and Lombok. Earth Observatory of Singapore.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.