In this monthly feature, we span the globe to examine Our Changing Landscape with time series of medium resolution RapidEye satellite imagery. The RapidEye archive dates back to late 2008 and already contains more than 5 billion square kilometers of data. This month, we look at changes in the landscape around Mount Tongariro, New Zealand following two 2012 eruptions.
The RapidEye Constellation
RapidEye is a constellation of five 5-meter medium resolution satellites each offering five spectral bands of information. The RapidEye constellation offers daily revisits to every location on the planet with a huge footprint that is 77-km wide. The data is priced competitively with a starting cost of $1.28 per square kilometer for all five spectral bands – academics do receive discounts. RapidEye adds a fifth band, the red edge, to the ‘traditional’ multispectral set of blue, green, red and near-infrared (NIR). The additional spectral data in the red edge band allows users to extract more useful land ‘information’ than can be from traditional 4-band imagery sources. When RapidEye imagery is ordered as a Level 3A Orthorectified product, images from multiple dates are extremely well registered, making it the ideal data source for Our Changing Landscape.
The 2012 Eruptions of Mount Tongariro, New Zealand
Mount Tongariro is a compound volcano located centrally on the smaller northern island of New Zealand. Mount Tongariro is comprised of at least 12 volcanic cones with Ngauruhoe the most active, having erupted more than 70 times since 1839. The volcano is 6,490 feet tall and is believed to have first erupted some 275,000 years ago. Mount Tongariro is nestled in one of New Zealand’s most popular tourist destinations, and its oldest national park, Tongariro National Park, which was made famous by its cameos in the Lord of the Rings trilogy.
After several weeks of minor seismic activity, during the wee hours of August 6, 2012, a gas and steam driven eruption occurred at 11:52 pm (local time) from existing vents as well as a new fissure on the Upper Te Maari Crater. The eruption sent an ash cloud some 6.1 kilometers (km) into the air and ejected large rocks up to 2-km from the carter. Volcanic emissions continued for days after the eruption with 2,100 tons of sulfur dioxide, 3,900 tons of carbon dioxide and 364 tons of hydrogen sulfide per day released as late as August 9th.
Shortly after 1:30 pm local time on November 21, 2012, another ash plume was ejected 3 to 4-km above the Upper Te Maari Crater in an eruption that lasted about 5 minutes. This ejection came from similar fissures involved in the August 6th event. There have been updates of seismic activity around Mount Tongariro since an August 6, 2013 report of very small earthquakes below the volcano.
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