Flores Back Arc Thrust Fault is a major system of west-east trending

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

s that extend eastwards from west of

Lombok Lombok is an island in West Nusa Tenggara province, Indonesia. It forms part of the chain of the Lesser Sunda Islands, with the Lombok Strait separating it from Bali to the west and the Alas Strait between it and Sumbawa to the east. It is rou ...

towards the islands of

Sumbawa Sumbawa is an Indonesian island, located in the middle of the Lesser Sunda Islands chain, with Lombok to the west, Flores to the east, and Sumba further to the southeast. Along with Lombok, it forms the province of West Nusa Tenggara, but there ...

Flores Flores is one of the Lesser Sunda Islands, a group of islands in the eastern half of Indonesia. Including the Komodo Islands off its west coast (but excluding the Solor Archipelago to the east of Flores), the land area is 15,530.58 km2, and th ...

, and Alor, with a total length of at least 800 km. The thrust faults are south- dipping and lie within the

back arc The back-arc region is the area behind a volcanic arc. In island volcanic arcs, it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs. In continental arcs, the back-ar ...

region of the

Sunda Sunda may refer to: Europe * Sunda, Faroe Islands India * Sunda (asura), an asura brother of Upasunda * Sunda (clan), a clan (gotra) of Jats in Haryana and Rajasthan, India Southeast Asia * Sundanese (disambiguation) ** Sundanese people ...

Banda Arc The Banda Arc (main arc, Inner, and Outer) is a set of island arcs in eastern Indonesia. It is the result of the collision of a continent and an intra-oceanic island arc. The presently active arc is located on what appears to be oceanic crust whe ...

, which is related to the ongoing

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

of the

Australian Plate The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when India broke ...

beneath the

and

Banda Sea Plate The Banda Sea Plate is a minor tectonic plate underlying the Banda Sea in southeast Asia. This plate also carries a portion of Sulawesi Island, the entire Seram Island, and the Banda Islands. Clockwise from the east it is bounded by the Bird's Hea ...

s. The thrust fault system developed as a result of the onset of

continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains prod ...

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...

of the Australian Plate reached the

Sunda Trench The Sunda Trench, earlier known as and sometimes still indicated as the Java Trench, is an oceanic trench located in the Indian Ocean near Sumatra, formed where the Australian- Capricorn plates subduct under a part of the Eurasian Plate. It is l ...

. The eastern part of the fault system is also known as the Wetar thrust. Above the main thrust fault are a series of imbricate (overlapping) thrust faults. These imbricate thrust faults are shallower in depth than the main Flores thrust. Although the exact thrust faults have not been established, these faults were thought to be responsible for the

2018 Lombok earthquake 2018 Lombok earthquake may refer to the following 5 thrust type earthquakes, with epicentres north of Rinjani volcano, that caused significant damage and deaths: *July 2018 Lombok earthquake ( and : 6.4, a foreshock) *5 August 2018 Lombok earthqua ...

References

Seismic faults of Southeast Asia Geology of Indonesia Thrust faults Seismic faults of Indonesia {{tectonics-stub