A tsunami (from Japanese: 津波, “harbour wave”;[1] English pronunciation: /suːˈnɑːmi/ soo-NAH-mee[2] or /tsuːˈnɑːmi/[3]) or tidal wave,[4], also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations, landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami.[5] Unlike normal ocean waves, which are generated by wind, or tides, which are generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water.

Tsunami waves do not resemble normal undersea currents or sea waves because their wavelength is far longer.[6] Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide.[7] For this reason, it is often referred to as a “tidal wave”, although this usage is not favoured by the scientific community because it might give the false impression of a causal relationship between tides and tsunamis.[8] Tsunamis generally consist of a series of waves, with periods ranging from minutes to hours, arriving in a so-called “internal wave train”.[9] Wave heights of tens of metres can be generated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enormous, and they can affect entire ocean basins. The 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history, with at least 230,000 people killed or missing in 14 countries bordering the Indian Ocean.

The Ancient Greek historian Thucydides suggested in his 5th century BC History of the Peloponnesian War that tsunamis were related to submarine earthquakes,[10][11] but the understanding of tsunamis remained slim until the 20th century and much remains unknown. Major areas of current research include determining why some large earthquakes do not generate tsunamis while other smaller ones do; accurately forecasting the passage of tsunamis across the oceans; and forecasting how tsunami waves interact with shorelines.




Ada yang bertanya, Webex itu apaan..

Untuk menjawabnya, saya ilustrasikan sebagai berikut.

Jika kita ingin mengadakan acara seperti seminar, pelatihan, pertemuan, rapat, pernikahan, dan lain-lain, tentu saja kita memerlukan tempat. Kita bisa mengadakannya di hotel, di aula, di gedung pertemuan, di ruang rapat, di halaman rumah, dan lain-lain.

Bila kita mengadakan acara di tempat kita sendiri, tentu saja kita tidak perlu membayar. Tapi, bila kita mengadakan acara di tempat milik orang lain, tentu saja kita harus mengeluarkan uang untuk menyewanya. Ini terjadi di dunia nyata. Intinya kita memerlukan tempat untuk mengadakan sebuah kegiatan atau acara, titik.

Di dalam dunia maya, kitapun bisa menyelenggarakan kegiatan-kegiatan seperti di dunia nyata. Salah satu tempat atau situs untuk menyelenggarakan kegiatan di dunia maya bernama Webex. Webex bukan punya kita. Jadi, kalau kita ingin menggunakan Webex untuk mengadakan kegiatan apapun harus membayar uang sewa. Ingat! Yang bayar itu kita yang mengadakan, bukan tamu atau peserta yang kita undang.

Salah satu lembaga yang menyewa Webex untuk mengadakan kegiatan online adalah SEAMEO (Perhimpunan Kementrian Pendidikan se Asia Tenggara). SEAMEO menggunakan Webex untuk mengadakan kegiatan-kegiatan online seperti sekarang ini, yaitu Pelatihan Koordinator Virtual yang lebih keren disebut dengan VCT. Dengan menggunakan Webex, peserta VCT seribu orangpun bisa bertemu dan berkumpul pada waktu yang sama, meskipun pada tempat yang berbeda. Jadi, dengan menggunakan Webex pula, para menteri atau pejabat kementrian pendidikan se Asia Tenggara bisa bertemu untuk berdiskusi atau apapun tanpa harus meninggalkan tempat masing-masing.

Lantas bisakah kita mengadakan kegiatan pertemuan MGMP, misalnya dengan menggunakan Webex?

Bisa. Caranya, kita pinjam Webex SEAMEO atau kita menyewa Webex sendiri kalau kita punya uang, hehehe.

Tapi jangan khawatir, Webex memberikan fasilitas gratis kalau hanya untuk pertemuan 3 orang, dan diberi fasilitas ujicoba bisa digunakan 25 orang selama 14 hari. Syaratnya, kita harus mendaftar di situs Webex. Yang menggembirakan, setelah ikut pelatihan ini, saya jadi tahu bahwa fasilitas yang untuk 25 orang itu bisa digunakan selamanya (bukan 14 hari saja) dengan trik tertentu.

Apa itu triknya, nanti saya share dalam tulisan berikutnya…


Cibinong, 28 Februari 2019

Yusuf Efendy



The Elephants

The elephants are the large mammals forming the family Elephantidae in the order Proboscidea. Three species are currently recognised: the African bush elephant (Loxodonta africana), the African forest elephant (L. cyclotis), and the Asian elephant (Elephas maximus). Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia. Elephantidae is the only surviving family of the order Proboscidea; other, now extinct, members of the order include deinotheres, gomphotheres, mammoths, and mastodons.

All elephants have several distinctive features, the most notable of which is a long trunk (also called a proboscis), used for many purposes, particularly breathing, lifting water, and grasping objects. Their incisors grow into tusks, which can serve as weapons and as tools for moving objects and digging. Elephants’ large ear flaps help to control their body temperature. Their pillar-like legs can carry their great weight. African elephants have larger ears and concave backs while Asian elephants have smaller ears and convex or level backs.

Elephants are herbivorous and can be found in different habitats including savannahs, forests, deserts, and marshes. They prefer to stay near water. They are considered to be a keystone species due to their impact on their environments. Other animals tend to keep their distance from elephants while predators, such as lions, tigers, hyenas, and any wild dogs, usually target only young elephants (or “calves”). Elephants have a fission–fusion society in which multiple family groups come together to socialise. Females (“cows”) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups are led by an individual known as the matriarch, often the oldest cow.

Males (“bulls”) leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate and enter a state of increased testosterone and aggression known as musth, which helps them gain dominance and reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness and show empathy for dying or dead individuals of their kind.

African elephants are listed as vulnerable by the International Union for Conservation of Nature (IUCN) while the Asian elephant is classed as endangered. One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.

Source: https://en.wikipedia.org/wiki/Elephant