Ecological Implications of Extreme Events: Footprints of the 2010 Earthquake along the Chilean Coast

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From: PLoS ONE(Vol. 7, Issue 5)
Publisher: Public Library of Science
Document Type: Article
Length: 6,054 words
Lexile Measure: 1640L

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Author(s): Eduardo Jaramillo 1 , * , Jenifer E. Dugan 2 , David M. Hubbard 2 , Daniel Melnick 3 , Mario Manzano 1 , Cristian Duarte 4 , Cesar Campos 1 , Roland Sanchez 1

Introduction

Chile overlies the convergent boundary between the Nazca plate and the South American continent (Fig. 1a), one of the most seismically active areas on Earth. Along the Chilean margin, plate convergence at ~70 mm/yr [1] results in great earthquakes (Mw ~8.0-8.5) on average every ~100-150 years, with occasional giant events ( Mw >9.0) every ~300 years [2], like the 1960 earthquake that reached a moment magnitude (Mw ) of 9.5. Such earthquakes result in substantial land-level changes of coastal and inland regions [3], [4], [5], [6]. The plate boundary off central Chile (ca. 34-38°S) ruptured last in 1835 and then on February 27, 2010. The 1835 event reached Mw ~8.5 [7], and its effects were documented by Fitz Roy and Darwin, who measured coseismic uplift of 2.4-3.0 m at Isla Santa Maria, southwest of Concepcion [8]. The recent 2010 rupture, known as the Maule earthquake, reached Mw 8.8 becoming the sixth largest event recorded by modern seismology [9], and third in the era of space geodesy following Sumatra 2004 and Japan 2011 [9]. Plate-boundary slip associated with the Maule earthquake reached 20 m, localized mostly in two patches to the north and south of the epicentre [10], [11], [12] (Fig. 1b). The response of the coastline to co-seismic slip depends on its position with respect to these areas of high slip release; thus, subsidence of ~1 m occurred along the coastline landward of the northern portion (34-35°S), whereas the coast above the southern portion, particularly the Arauco Peninsula (37°S), was uplifted up to 2.5 m [4], [5], [6]. The Maule event triggered a devastating tsunami that killed nearly 500 people [13], destroyed coastal infrastructure, and further reshaped coastal landscapes [4], [5], [6].

Figure 1. Index maps and land-level changes from the 2010 Maule earthquake. a, Plate-tectonic setting of Chilean margin. Arrows indicate convergences between Nazca and South American plates at circa 70 mm yr-1 . b, Maule earthquake setting. Epicentre indicated by star, green contours show plate boundary slip (m) (10). Beach sites: Boyeruca* (Bo), Iloca* (Ilo), Pelluhue* (Pe), Lenga (Le), Colcura (Col), Punta Lavapie* (Lv), Llico* (Lli), Las Peñas (LP) and Lebu* (Leb). Land-level change estimated at sites with * plus Cocholhue (Co), Chome (Cho), Maule (Ma), Isla Santa María (ISM), Quidico (Qui), Tirúa (Tir) and Isla Mocha (IMo) (Table S2). c, Geographic variability in estimated land-level changes (means ±1 standard deviation). Black dot denotes coseismic subsidence at permanent GPS site CONT [51]; black diamonds are estimates of subsidence based on drowned coastlines. [see PDF for image]

Ecological footprints of large-scale extreme events, such as earthquakes, tsunamis, volcanic eruptions, fires and climatic phenomena, can persist for years, decades, centuries and even millennia [14], [15], [16], [17], [18], [19], [20]. For example, the gradation of muddy sedimentary and peaty layers representing...

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Gale Document Number: GALE|A477130392