The dog-leg-shaped Philippine Trench is propagating southward across the fragmented Halmahera arc terrane and its southern segment could reactivate a former strike-slip fault zone. The Miangas-Pujada-Talaud ridge is part of the Sangihe forearc, and the ophiolites could represent its basement, uplifted along the outer arc ridge. There is no clear evidence for accreted oceanic crust belonging to the recently subducted Molucca Sea. It could be either an accretionary wedge developed at the deformed leading edge of the Sangihe forearc or be part of a former intra-arc basin which was part of the colliding Halmahera arc terrane. The thickness of this wedge cannot be explained by subduction along the very young Philippine Trench. If the block opposite an observer looking across. East of the Miangas-Pujada-Talaud ridge there is a wide sedimentary wedge separated from the Snellius Ridge to the south by the major NW-SE crustal discontinuity. Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally. Snellius volcanic plateau, a fragment of the Halmahera arc terrane, has induced the formation ofĪ new plate boundary, the Philippine Trench along what is interpreted as a former strike-slip fault zone. Left-Lateral Transform, Based on the video 'Where the fault lies,' the most powerful earthquake in the historical records with an epicenter in California occurred in which year and location Select one: a. South of 6°N the westward subduction of the buoyant North of 6°N the Philippine Trench inner wall isĭissected by NW-SE trending left-lateral strike-slip faults, resulting from the dominantly obliqueĬonvergence between colliding arcs. Interpreted as a left-lateral strike-slip fault. Of the ridge very contrasting terranes are separated by a major NW-SE crustal discontinuity The central part of the Molucca Sea appears to be a backstop within the Sangihe forearc. Presence of an almost complete Sangihe arc and forearc. Preliminary interpretation of these data reveals the Strike-slip fault - a fault on which the two blocks slide past one another. The San Andreas Fault is an example of a right lateral fault.Ī left-lateral strike-slip fault is one on which the displacement of the far block is to the left when viewed from either side.Ī right-lateral strike-slip fault is one on which the displacement of the far block is to the right when viewed from either side.A swath mapping, gravity and single channel seismic survey was carried out in the The left-lateral offsets consist of multiple inflections produced by seismic events, and the offset of each event is similar. Reverse (thrust) fault - a dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. This type of faulting is common in areas of compression, such as regions where one plate is being subducted under another as in Japan. When the dip angle is shallow, a reverse fault is often described as a thrust fault. Normal fault - a dip-slip fault in which the block above the fault has moved downward relative to the block below. This type of faulting occurs in response to extension and is often observed in the Western United States Basin and Range Province and along oceanic ridge systems. The following definitions are adapted from The Earth by Press and Siever. A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake - or may occur slowly, in the form of creep. Faults may range in length from a few millimeters to thousands of kilometers. Most faults produce repeated displacements over geologic time. During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. The fault surface can be horizontal or vertical or some arbitrary angle in between.Įarth scientists use the angle of the fault with respect to the surface (known as the dip) and the direction of slip along the fault to classify faults. Faults which move along the direction of the dip plane are dip-slip faults and described as either normal or reverse (thrust), depending on their motion. Faults which move horizontally are known as strike-slip faults and are classified as either right-lateral or left-lateral. Faults which show both dip-slip and strike-slip motion are known as oblique-slip faults.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |