Where on Earth...? MISR Mystery Image Quiz #14: Anatahan Island

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This natural-color image of Anatahan Island from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on the Terra satellite represents an area of about 296 kilometers x 353 kilometers, and was acquired by MISR's nadir (vertical-viewing) camera on May 24, 2003. These data were processed at the NASA Langley Atmospheric Science Data Center. Terra circles the Earth in the same orbit as Landsat 7, flying at an altitude of about 700 kilometers above the Earth's surface. Answers to the questions are provided.

1. The island is part of a volcanic arc system situated near a tectonic plate boundary.

   • Answer: TRUE
     Anatahan Island is one of the Northern Mariana Islands in the western tropical Pacific. These islands are situated along the Izu-Mariana margin where subduction of the Pacific plate beneath the Philippine Sea plate creates a series of island arc volcanoes and the Earth's deepest ocean trench.

2. The last major volcanic eruption on this island occurred in 1981.

   • Answer: FALSE
     Anatahan had no known historical eruptions until May 2003.

3. The island contains mixed broadleaf forests, weathered clay soils, and a lake infused by volcanic gases which raise the water's pH to about 10.

   • Answer: FALSE
     The infusion of volcanic gases lowers the pH of a water body. Volcanic gases such as CO₂ and SO₂ react with water to form carbonic and sulfuric acids, respectively.

4. The type of clouds pictured here are often associated with lightning and sustained rainstorms lasting several hours or more.

   • Answer: FALSE
     The small cumulus clouds pictured here are not deep enough to produce more than the occasional shower.

5. The island is inhabited by an endangered species of bird whose newly-hatched young are feathered, able to walk, and able regulate their body temperature.

   • Answer: TRUE
     The Micronesian Megapode is an endangered species of bird that inhabits the island. Megapode chicks are precocial at hatching and the adults do not need to care for the young.

6. Snorkelers around this island are likely to encounter Acanthurus achilles and Zanclus cornutus.

   • Answer: TRUE
     Both fish, the Achilles Tang and the Moorish Idol, are found in the subtropical waters of the Mariana Islands.

7. The archipelago to which the island belongs was spotted in 1521 by a Portuguese explorer who named the islands after the wife of a Spanish king.

   • Answer: FALSE
     Although Portuguese explorer Ferdinand Magellan spotted the islands in 1521, he named them "Las Isles de las Velas Latinas" (The Islands of the Latine Sails). He later changed the name to "Las Islas de Los Ladrones" (The Islands of Thieves). Eventually (in 1668), the Spanish renamed them "Las Marianas" in honor of Mariana of Austria, the widow of Spanish King Philip IV.

8. The island is part of an archipelago that was claimed as a territory of one nation in 1920 and of another nation in 1944.

   • Answer: Both TRUE and FALSE answers accepted
     Japan took control of the Mariana Islands in 1914 (the first year of World War l) and Germany released the islands to Japan in 1919. Japan received a mandate over the islands in 1920 (after the ratification of the League of Nations). American forces gained control of the islands in 1944, but it was not until 1947 that the area was recognized as a Trust Territory of the United States by the United Nations.

9. The wreckage of a two-engine propeller-driven bomber is located on the island.

   • Answer: FALSE
     The wreckage of a World War II B-29 Superfortress lies on the north side edge of the craters flat lands. However, the B-29 is a four-engine propeller-driven bomber.

10. A director who made several films starring Marlene Dietrich also directed her in a movie whose title contains this island's name.

    • Answer: FALSE
      Fievre sur Anatahan (The Saga of Anatahan) (1953), is a film directed by Josef von Sternberg, who made many films starring Marlene Dietrich. However, she is not in this film.

11. In spring of 1990 the island's residents were evacuated because of the impending landfall of a devastating typhoon.

    • Answer: FALSE
      The evacuation of the island's residents in 1990 was prompted by a shallow earthquake swarm that suggested the possibility of impending volcanic activity.

12. Bonus question: MISR captured this image of the island and its surroundings on either January 6, March 11, or May 14. True or false?

    • Answer: FALSE
      The eruption of Anatahan began on May 10th, but the Terra satellite did not pass over this area on May 14th. One way to verify that the image was not acquired on May 14th is to find another satellite image of Anatahan on May 14th. For example, this view of Anatahan from the Aqua satellite shows that on May 14th the plume was blown toward the west, but the plume points toward the south in the MISR image. You can determine exactly when MISR captured this image by using the geographic coordinates of the islands, a map of World Reference System-2 descending orbits (remember, Terra circles the Earth in the same orbit as Landsat 7!) and visiting the MISR section at the NASA-Langley Atmospheric Science Data Center. This image of the Anatahan eruption was acquired on May 24, 2003 (during Terra orbit 18242).

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
Text acknowledgment: Clare Averill (Acro Service Corporation/Jet Propulsion Laboratory), David J. Diner (Jet Propulsion Laboratory).