Chain Survey
Chain Survey
Chain survey is the simplest method of surveying. In this survey only measurements are taken in the field, and the rest work, such as plotting calculation etc. are done in the office. This is most suitable adapted to small plane areas with very few details. If carefully done, it gives quite accurate results. The necessary requirements for field work are chain, tape, ranging rod, arrows and some time cross staff.
Survey Station:
Survey stations are of two kinds
- Main Stations
- Subsidiary or tie
Main Stations:
Main stations are the end of the lines, which command the boundaries of the survey, and the lines joining the main stations re called the main survey line or the chain lines.
Subsidiary or the tie stations:
Subsidiary or the tie stations are the point selected on the main survey lines, where it is necessary to locate the interior detail such as fences, hedges, building etc.
Tie or subsidiary lines:
A tie line joints two fixed points on the main survey lines. It helps to checking the accuracy of surveying and to locate the interior details. The position of each tie line should be close to some features, such as paths, building etc.
Base Lines:
It is main and longest line, which passes approximately through the centre of the field. All the other measurements to show the details of the work are taken with respect of this line.
Check Line:
A check line also termed as a proof line is a line joining the apex of a triangle to some fixed points on any two sides of a triangle. A check line is measured to check the accuracy of the framework. The length of a check line, as measured on the ground should agree with its length on the plan.
Offsets:
These are the lateral measurements from the base line to fix the positions of the different objects of the work with respect to base line. These are generally set at right angle offsets. It can also be drawn with the help of a tape. There are two kinds of offsets:
1) Perpendicular offsets, and
2) Oblique offsets.
The measurements are taken at right angle to the survey line called perpendicular or right angled offsets.
2) Oblique offsets.
The measurements are taken at right angle to the survey line called perpendicular or right angled offsets.
The measurements which are not made at right angles to the survey line are called oblique offsets or tie line offsets.
Procedure in chain survey:
1. Reconnaissance:
The preliminary inspection of the area to be surveyed is called reconnaissance. The surveyor inspects the area to be surveyed, survey or prepares index sketch or key plan.
2. Marking Station:
Surveyor fixes up the required no stations at places from where maximum possible stations are possible.
3. Then he selects the way for passing the main line, which should be horizontal and clean as possible and should pass approximately through the centre of work.
4. Then ranging roads are fixed on the stations.
5. After fixing the stations, chaining could be started.
6. Make ranging wherever necessary.
7. Measure the change and offset.
8. Enter in the field the book.
Deadliest Earthquakes on Record
(50,000 deaths or more)
The following table lists the deadliest earthquakes on record according to date, location, number of deaths, and magnitude. On Jan. 23, 1556, an 8.0 magnitude earthquake struck Shansi, China killing 830,000 people.
| Date | Location | Deaths | Magnitude |
| Jan. 23, 1556 | Shansi, China | 830,000 | ~8 |
| July 27, 1976 | Tangshan, China | 255,0001 | 7.5 |
| Aug. 9, 1138 | Aleppo, Syria | 230,000 | n.a. |
| Dec. 26, 2004 | off west coast of northern Sumatra | 225,000+ | 9.0 |
| Jan. 12, 2010 | Haiti | 222,570 | 7.0 |
| Dec. 22, 8562 | Damghan, Iran | 200,000 | n.a. |
| May 22, 1927 | near Xining, Tsinghai, China | 200,000 | 7.9 |
| Dec. 16, 1920 | Gansu, China | 200,000 | 7.8 |
| March 23, 8932 | Ardabil, Iran | 150,000 | n.a. |
| Sept. 1, 1923 | Kwanto, Japan | 143,000 | 7.9 |
| Oct. 5, 1948 | Ashgabat, Turkmenistan, USSR | 110,000 | 7.3 |
| Dec. 28, 1908 | Messina, Italy | 70,000– 100,0003 | 7.2 |
| Sept. 1290 | Chihli, China | 100,000 | n.a. |
| May 12, 2008 | Eastern Sichuan, China | 87,587 | 7.9 |
| Oct. 8, 2005 | Pakistan | 80,361 | 7.6 |
| Nov. 1667 | Shemakha, Caucasia | 80,000 | n.a. |
| Nov. 18, 1727 | Tabriz, Iran | 77,000 | n.a. |
| Dec. 25, 1932 | Gansu, China | 70,000 | 7.6 |
| Nov. 1, 1755 | Lisbon, Portugal | 70,000 | 8.7 |
| May 31, 1970 | Peru | 66,000 | 7.9 |
| May 30, 1935 | Quetta, Pakistan | 30,000– 60,000 | 7.5 |
| Jan. 11, 1693 | Sicily, Italy | 60,000 | n.a. |
| 12684 | Silicia, Asia Minor | 60,000 | n.a. |
| June 20, 1990 | Iran | 50,000 | 7.7 |
| Feb. 4, 1783 | Calabria, Italy | 50,000 | n.a. |
1. Official. Estimated death toll as high as 655,000.
2. Note that these dates are prior to A.D. 1000. No digit is missing.
3. Estimated.
4. No date available.
Source: National Earthquake Information Center, U.S. Geological Survey. Data compiled from several sources.
Recent Volcanic Activity
The following table shows the recent and ongoing volcanic history around the world by year of activity and volcano name.
(Bold indicates activity in 2008, 2009, and 2010)
| Volcano | Year of last eruption or activity |
|---|---|
| Adatara, Honshu, Japan | 1997 |
| Akan, Hokkaido, Japan | 2006 |
| Akutan, Alaska | 1996 |
| Ambrym Island, Vanuatu | 2007 |
| Amukta, Alaska | 1996 |
| Anatahan, Mariana Islands | 2007 |
| Aoba, Ambae Island, Vanuatu | 2006 |
| Arenal, Costa Rica | ongoing |
| Asama, Honshu, Japan | 2003 |
| Aso, Kyushu, Japan | 2004 |
| Atka, Aleutian Islands, United States | 2006 |
| Augustine, Cook Inlet, Alaska, United States | 2006 |
| Axial Seamount | 1998 |
| Bamus, New Britain Island, Papua New Guinea | 2006 |
| Bandai, Honshu, Japan | 2000 |
| Bagana, Bougainville, Papua New Guinea | ongoing |
| Barren Island, Indian Ocean | 2008 |
| Batu Tara, Lesser Sunda Islands, Indonesia | 2007 |
| Bezymianny, Kamchatka, Russia | 2009 |
| Bromo, Java, Indonesia | 2000 |
| Bulusan, Philippines | 2007 |
| Mount Cameroon, Cameroon | 2000 |
| Canlaon, Philippines | 2006 |
| Cerro Azul, Galápagos Islands, Ecuador | 1998 |
| Cerro Negro, Nicaragua | 1999 |
| Chaitén, Chile | 2008 |
| Chikurachki, Kurile Islands, Russia | 2005 |
| Chiginagak, Alaska | 1997 |
| Chuginadak, Alaska | 2005 |
| Cleveland, Chuginadak Island, Alaska | 2008 |
| Colima, Mexico | ongoing |
| Conception, Island of Ometepe, Nicaragua | 2010 |
| Copahue, Argentina and Chile | 2000 |
| Dempo, Sumatra Indonesia | 2006 |
| Dukono, Indonesia | ongoing |
| East Epi, Vanuatu | 2004 |
| Eastern Gemini Seamount, Vanuatu | 1996 |
| Ebeko, Kuril Islands, Russia | 2007 |
| Egoni, Indonesia | 2004 |
| Erta Ale, Ethiopia | 2003 |
| Etna, Sicily, Italy | 2007 |
| Eyjafjallajokull, Iceland | 2010 |
| Fernandina, Galápagos | 1995 |
| Fogo, Cape Verde | 1995 |
| Piton de la Fournaise, France | 2010 |
| Fourpeaked, Alaska Peninsula, United States | 2006 |
| Fuego, Guatemala | ongoing |
| Fukutoku-Okanoba, Japan | 2010 |
| Galeras, Colombia | 2008 |
| Gamalama, Indonesia | 2003 |
| Gaua, Vanuatu | 2009 |
| Grimsvotn, Iceland | 1998 |
| Guagua Pichincha, Ecuador | 2006 |
| Hachijo-Jima, Izu Islands, Japan | 2002 |
| Hakkoda, Japan | 1997 |
| Heard Island, Southern Indian Ocean, Australia | 2006 |
| Hekla, Iceland | 2000 |
| Mount Hili Aludo, Indonesia | 1997 |
| Hokkaido, Japan | 2006 |
| Home Reef, Tonga Islands, Tonga | 2006 |
| Hosho, Kyushu, Japan | 1995 |
| Ijen, Java, Indonesia | 2001 |
| Iwate-san, Honshu, Japan | 1998 |
| Jackson Segment, N. Gorda Ridge (nr. Oregon) | 2001 |
| Kaba, Sumatra, Indonesia | 2000 |
| Mount Karangetang, Indonesia | 2007 |
| Karthala, Comoros Islands, Indian Ocean | 2007 |
| Karymsky, Kamchatka, Russia | ongoing |
| Kavachi Seamount, Solomon Islands | 2004 |
| Kelut, Java, Indonesia | 2006 |
| Kick-'em-Jenny (nr. Grenada) | 2003 |
| Kikai, Japan | 2004 |
| Kilauea, Hawaii | ongoing |
| Kirishima, Japan | 2010 |
| Kliuchevskoi, Kamchatka, Russia | 2009 |
| Komagatake, Hokkaido, Japan | 2000 |
| Korovin, Alaska | 1998 |
| Krakatau, Indonesia | 2001 |
| Langila, New Britain, P.N.G. | 2007 |
| Lamongan, Indonesia | 2003 |
| Lascar, Chile | 2007 |
| Leroboleng, Indonesia | 2003 |
| Mount Lewotobi, Indonesia | 2003 |
| Llaima, Chile | 2008 |
| Loihi Seamount, Hawaii | 1996 |
| Lokon, Sulawesi, Indonesia | 2003 |
| Long Valley caldera, California | 1996 |
| Lopevi, Central Islands, Vanuatu | 2007 |
| La Madera, Nicaragua | 1996 |
| Manam, Papua New Guinea | ongoing |
| Maroa, New Zealand | 2001 |
| Masaya, Nicaragua | ongoing |
| Mauna Loa, Hawaii | 2003 |
| Mayon, Philippines | 2009 |
| McDonald Island, Australia | 1996 |
| Merapi, Indonesia | 2007 |
| Metis Shoal, Tonga | 1995 |
| Momotombo, Nicaragua | 1996 |
| Monowai Seamount, Kermadec Islands | 1997 |
| Nevado Del Huila, Colombia | 2007 |
| Nyamuragira, Congo (Dem. Rep.) | 2010 |
| Nyiragongo, Congo (Dem. Rep.) | 2003 |
| Okmok, Alaska | 1997 |
| Ol Doinya Lengai, Tanzania, Africa | 2006 |
| Oyama, Miyake-jima, Izu Islands, Japan | 2006 |
| Pacaya, Guatemala | 2007 |
| Pagan, Mariana Islands, central Pacific Ocean | 2006 |
| Pago, Papua New Guinea | 2004 |
| Papandayan, Java, Indonesia | 2002 |
| Pavlof, Alaska | 1997 |
| Peuet Sague, Indonesia | 1998 |
| Piparo, Trinidad | 1997 |
| Piton de la Fournaise, Réunion | 2007 |
| Poas, Costa Rica | 2006 |
| Popocatepetl, Mexico | 2007 |
| Rabaul, Papua New Guinea | 2008 |
| Raoul Island, New Zealand | 2006 |
| Redoubt, Alaska | 2009 |
| Reventador, Ecuador | 2007 |
| Rincon de la Vieja, Costa Rica | 1998 |
| Ritter Island, Papua New Guinea | 2006 |
| Rotorua, New Zealand | 2001 |
| Ruapehu, New Zealand | 2006 |
| Ruby Seamount, Mariana Islands | 1995 |
| Mount St. Helens, Washington | ongoing |
| Sakura-Jima, Japan | ongoing |
| San Cristobal, Nicaragua | 2006 |
| San Miguel, El Salvador | 2006 |
| Sangay, Ecuador | ongoing |
| Santa Ana, El Salvador | 2006 |
| Santa Maria, Guatemala | ongoing |
| Semeru, Java, Indonesia | ongoing |
| Shiveluch, Kamchatka, Russia | ongoing |
| Shin-dake, Kuchinoerabujima Island, Japan | 1999 |
| Shishaldin, Unimak Island, Alaska | 2000 |
| Simbo, Solomon Islands | 2006 |
| Slamet, Java Indonesia | 2007 |
| Soputan, Indonesia | 2006 |
| Soufriere Hills, Montserrat, West Indies | ongoing |
| South Sister, Oregon | 2001 |
| Stromboli, Italy | ongoing |
| Sulu Range, New Britain Island, Papua New Guinea | 2006 |
| Suwanose-Jima Ryukyu Islands, Japan | ongoing |
| Tavurvur, Papua New Guinea | 2000 |
| Taal, Philippines | 2006 |
| Talang, Indonesia | 2007 |
| Telica, Nicaragua | 2007 |
| Tengger Caldera, Java, Indonesia | 2006 |
| Terceira, Azores | 1999 |
| Tonga (unnamed volcano) | 1999 |
| Tongariro Volcanic Centre, New Zealand | 2006 |
| Tungurahua, Ecuador | ongoing |
| Turrialba, Costa Rica | 2010 |
| Ubinas, Peru | 2007 |
| Ulawun, Papua New Guinea | 2007 |
| Usu, Japan | 2000 |
| Veniaminof, Alaska | 2006 |
| Villarrica, Chile | 2009 |
| White Island, New Zealand | 2007 |
| Yasur, Tanna Island, Vanuatu | 2004 |
| Yellowstone, Wyoming | 1998 |
| Zacatecas, Mexico | 1997 |
Source: Global Volcanism Program. Web: volcano.und.edu/vw.html .
