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21-662: The Marikina Valley fault system , also known as the Valley fault system ( VFS ), is a dominantly right-lateral strike-slip fault system in Luzon , Philippines. It extends from Doña Remedios Trinidad , Bulacan in the north, running through the provinces of Rizal , the Metro Manila cities of Quezon , Marikina , Pasig , Taguig and Muntinlupa , and the provinces of Cavite and Laguna , before ending in Canlubang in

42-803: A subspecific name. For purposes of future reference, they selected as holotype a shell with a color pattern quite distinct from any which have been named. Thus, the name butoti can at least be used for the color variation if it is decided to include the Kangean populations in the nominate form of perversus . Besides the nominate color pattern of butoti , shells referable to the infraviridis , infrapictus , rufocinctus , sultanus and typical perversus pattern were seen on Kangean Island. Paratypes: Specimens were seen from several localities on Kangean Island. The shells from Sepandjang are in Chicago Natural History Museum , no. 97808, in

63-562: Is 129.47 kilometers (80.45 mi) long. The West Valley Fault is capable of producing large-scale earthquakes during its active phases with a magnitude of 7 or higher. The eastern segment, known as the East Valley Fault (EVF) , moves in an oblique dextral motion. It extends about 17.24 kilometers (10.71 mi) from Rodriguez to San Mateo in the province of Rizal . Based on kinematic block models that utilize GPS, actual fault geometry, and earthquake focal mechanisms,

84-687: Is the type species of the genus Amphidromus , by the subsequent designation of Eduard von Martens (1860). There are six subspecies of Amphidromus perversus : Distribution of Amphidromus perversus include Sumatra and Java to Borneo , Sulawesi and Bali . Absent from the Mentawi Chain and Panaitan Island . Its occurrence on Sumbawa needs confirmation. Probably it has been introduced into Singapore . Subspecies recognized here are from Great Natuna , Bawean , Kangean Islands and Riau Islands . Amphidromus perversus are amphidromine (left-handed and right-handed snails occur in

105-446: Is their asymmetric morphology: both eyes are on the same side of the head in the adult fish. In some families of flatfish, the eyes are always on the right side of the body ( dextral or right-eyed flatfish), and in others, they are always on the left ( sinistral or left-eyed flatfish). Primitive spiny turbots include equal numbers of right- and left-sided individuals, and are generally more symmetric than other families. In geology ,

126-548: Is white with rather numerous brown flammulations that become confluent on the base, elongate, and quite slender. Apparently it is a white derivative from the interruptus stock, which may have a definite geographic separation in Bali and Java. Material from Kedewan , East Java (Butot, Chicago Natural History Museum 72404) ranged from 43.5 to 48 mm in height. Range: Riau Archipelago near Singapore and possibly Perak and Biliton Island off Borneo. Remarks: The purple apex ,

147-881: The Zoological Museum in Amsterdam , and in Butot ; Djukung specimens are in the Zoological Museum in Amsterdam; and topotypes from Bajutan are in Chicago Natural History Museum, no. 97806, and in Butot and the Zoologisch Museum, Amsterdam, Some additional material from Kangean Island (USNM 468416, Paravicini!) was seen after the description had been written. Range: Central and East Java, possibly Bali. Remarks: The shell

168-592: The Singapore area and Riau Archipelago. Range: Great Natuna Islands ; possibly the South Natuna and Anamba Islands also. The yellow peripheral band of melanomma is absent; otherwise this is close to the Riau population. Amphidromus perversus natunensis is quite variable in color, ranging from white to dark (see Pilsbry 1900, pp. 162–163). Possibly some of the material that Jacobi (1895) dissected under

189-414: The coloration and the strong polish are the only features separating this race from the other subspecies. Remarks: The problem of how to treat insular populations which show minor divergence from the main stocks is far from being satisfactorily settled. The intense coloration of the Kangean populations shows a minor difference from the main populations and Laidlaw & Solem (1961) have recognized it with

210-431: The fault the left side moves toward the observer. Movement is dextral (right-handed) if the block on the other side of the fault moves to the right, or if straddling the fault the right side moves toward the observer. Amphidromus perversus Amphidromus perversus is a species of air-breathing land snail , a terrestrial pulmonate gastropod mollusc in the family Camaenidae . Amphidromus perversus

231-400: The fault, and it endangers 6,331 buildings in a span of 2,964.10 square kilometers (1,144.45 sq mi), where the majority are houses with 19 schools included in the list. Sinistral and dextral Relative direction and chirality are distinct concepts. Relative direction is from the point of view of the observer; a completely symmetric object has a left side and a right side, from

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252-473: The names Amphidromus interruptus and Amphidromus chloris belongs here, but the shells were not figured and their location is unknown. The South Natuna Island record needs confirmation, while specimens from Siantan , Anamba Islands (CNHM 72427), are referred by Laidlaw & Solem (1961) with some hesitation. Range: Bawean Island , Java . This weakly characterized race differs primarily by its intense color, strong color zone, and slight white margin at

273-502: The numerous wavy brown flammulations that are partially interrupted by a yellow peripheral color band, and the solid shell are characteristic. This variety is similar to sultanus , but has only partial interruption of the stripes by the color band and has the purple apex. The Biliton record from the early Samarang voyage is questionable, and it is quite possible that the Perak records of De Morgan are in error. The only certain localities are

294-622: The object, regardless of the position of the observer. Because the coiled shells of gastropods are asymmetric, they possess a quality called chirality –the "handedness" of an asymmetric structure. Over 90% of gastropod species have shells in which the direction of the coil is dextral (right-handed). A small minority of species and genera have shells in which the coils are almost always sinistral (left-handed). Very few species show an even mixture of dextral and sinistral individuals (for example, Amphidromus perversus ). The most obvious characteristic of flatfish , other than their flatness,

315-486: The observer's point of view, if the top and bottom and direction of observation are defined. Chirality, however, is observer-independent: no matter how one looks at a right-hand screw thread , it remains different from a left-hand screw thread. Therefore, a symmetric object has sinistral and dextral directions arbitrarily defined by the position of the observer, while an asymmetric object that shows chirality may have sinistral and dextral directions defined by characteristics of

336-489: The population). In Amphidromus perversus and most other thick-shelled Amphidromus species, the lip is internally thickened, forms a "roll" in its expansion, and has a very heavy parietal callus . The shell is solid, polished, amphidromine, moderately large (45–55 mm) high, usually with a dark varix. Lip and callus white; ground color white, orange, yellow, or yellowish-green. Many specimens with interrupted or continuous radial brownish streaks covering part or all of

357-770: The south. The fault contains two major segments: the West Valley Fault (WVF) and the East Valley Fault (EVF). The western segment, known as the West Valley Fault (WVF) , is one of the two major fault segments of the Valley Fault System, which runs through the cities of Marikina , Quezon City , Pasig , Taguig and Muntinlupa in Metro Manila and moves in a dominantly dextral strike-slip motion. The West Valley Fault segment extends from Doña Remedios Trinidad to Calamba and

378-509: The suture. Of seventeen shells collected in May, 1954, by Hoogerwerf at Telaga Kastoba , Bawean Island, ten were dextral and seven sinistral. Three lacked a varix, one was grass green in color, three were whitish, and thirteen had yellow ground color. The name sankapurus Fruhstorfer, 1905, refers to white shells with a very dark color band. This variation is similar to Amphidromus perversus butoti . This article incorporates public domain text from

399-416: The terms sinistral and dextral refer to the horizontal component of the movement of blocks on either side of a fault or the sense of movement within a shear zone . These are terms of relative direction, as the movement of the blocks is described relative to each other when viewed from above. Movement is sinistral (left-handed) if the block on the other side of the fault moves to the left, or if straddling

420-655: The western segment of the Marikina Valley fault system was resolved to be almost fully locked, meaning it is currently accumulating and loading elastic strain at a rate of 10 to 12 mm/yr. The fault poses a threat of a large-scale earthquake with an estimated magnitude between 6–7 and as high as 7.6 to Metro Manila and surrounding provinces, with a death toll predicted to be as high as 35,000 and some 120,000 or higher injured and more than three million needed to be evacuated. There are 99 private villages and subdivisions inside 80 barangays traversed directly by

441-525: The whorls on the lower spire and body whorl . Amphidromus perversus undoubtedly offers the greatest array of discretely variable color combinations of any species of Amphidromus . Color variation of Amphidromus perversus perversus include 12 forms: Holotype: Zoological Museum in Amsterdam . The type locality is Bajutan , Kangean Islands . Collected by Hoogerwerf on August 20, 1954. Description: A brilliantly colored series of populations with highly polished shell surface. The general intensity of

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