The 17 July 2006 magnitude Mw 7.8 earthquake off the south coast of western Java, Indonesia, gene... more The 17 July 2006 magnitude Mw 7.8 earthquake off the south coast of western Java, Indonesia, generated a tsunami that effected over 300 km of coastline and killed more than 600 people, with locally focused runup heights exceeding 20 m. This slow earthquake was hardly felt on Java, and wind waves breaking masked any preceding withdrawal of the water from the shoreline, making this tsunami difficult to detect before impact. An International Tsunami Survey Team was deployed within one week and the investigation covered more than 600 km of coastline. Measured tsunami heights and run-up distributions were uniform at 5 to 7 m along 200 km of coast; however there was a pronounced peak on the south coast of Nusa Kambangan, where the tsunami impact carved a sharp trimline in a forest at elevations up to 21 m and 1 km inland. Local flow depth exceeded 8 m along the elevated coastal plain between the beach and the hill slope. We infer that the focused tsunami and runup heights on the island su...
bay-mouth bar some 200 m seaward of the deposit. We took approximately 100 core samples of this d... more bay-mouth bar some 200 m seaward of the deposit. We took approximately 100 core samples of this deposit in an attempt to characterize lateral grain size trends within the sand. Although the coarse fraction does fine with distance inland, the fine fraction does not change size over the study area, and the aggregate grain size changes in no systematic way. We interpret this deposit to represent the mixture of material picked up at the bar with material picked up at the gravel shoreline. The bar material does not fine in part because it is already fairly well sorted, but also because it is far from its source. The shoreline material, on the other hand, is poorly sorted so that the tsunami took only those grains it was capable of moving, and deposited them closer to their source. We estimated the size of the tsunami by determining the flow depth-flow velocity combinations required to advect sand from the bar to the back of the deposit, and by estimating the shear velocity required for motion of the largest grain we found during our survey. This modeling indicates an average flow depth of about 2.5-2.8 m over the area, at a flow velocity of 1.9-2.2 m/s. This estimate compares well with eyewitness accounts of a maximum flow depth of 7 m at the shoreline if our estimate represents an average over the whole study area.
Eos, Transactions American Geophysical Union, 2000
Vanuatu is a volcanic archipelago located some 2000 km northeast of Australia, in the heart of Me... more Vanuatu is a volcanic archipelago located some 2000 km northeast of Australia, in the heart of Melanesia. The islands are mainly agricultural, but are also a tourist destination for Australians and New Zealanders, many of whom come to see the active volcanoes on Ambrym and Tanna, and the annual practice of "land diving" on Pentecost. An earthquake estimated between moment magnitude 7.1 and 7.5 occurred off the east coast of Vanuatu on November 26, 1999 at 13:21 UTC-the earthquake generated a damaging tsunami that struck the coast of Vanuatu, where it reached as high as 6.6 meters above sea level and destroyed an entire village (Figures 1 and 2). Remarkably, only 5 people were killed by the tsunami, most likely because the villagers were well informed about tsunamis and their effects. Two weeks after the tsunami, our group spent six days interviewing eyewitnesses to the disaster, surveying damage caused by the waves, and measuring sand and debris left by the tsunami. We hope to use this data to understand the factors that lead to loss of life during a tsunami, to provide benchmark data for computer simulations of tsunamis, and to understand how to identify the traces left by ancient tsunamis. The earthquake and tsunami Vanuatu consists of an island arc formed by the subduction of the Australian plate under the Pacific plate (Figure 2B). Vanuatu is seismically active, with magnitude 5-6 events common, especially in the Central Basin area bounded by Espiritu Santo and Malakula on the west, and Maewo and Pentecost on the east. A magnitude 6.4 event occurred in the central basin in 1965, followed the next day by a magnitude 7.0 earthquake near Epi. A magnitude 7.0 earthquake also occurred in 1981 south of Malakula. Because of Vanuatu's steep topography, landslides commonly accompany earthquakes-these landslides may also occur offshore. Wong and Greene (1988) noted many large submarine landslides in the Central Basin that could have triggered tsunamis. Previous tsunamis occurred in 1875 ("Vanuatu"), 1961 (south of Efate), and 1965, which saw two tsunamis a day apart (the first in the Central
The 2004 Sumatra-Andaman tsunami flooded coastal northern Sumatra to a depth of over 20 m, deposi... more The 2004 Sumatra-Andaman tsunami flooded coastal northern Sumatra to a depth of over 20 m, deposited a discontinuous sheet of sand up to 80 cm thick, and left mud up to 5 km inland. In most places the sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet may record the passage of up to 3 individual waves. We studied the 2004 tsunami deposits in detail along a flow-parallel transect about 400 m long, 16 km southwest of Banda Aceh. Near the shore along this transect, the deposit is thin or absent. Between 50 and 400 m inland it ranges in thickness from 5 to 20 cm. The main trend in thickness is a tendency to thicken by filling low spots, most dramatically at pre-existing stream channels. Deposition generally attended inundation—along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. Although the tsunami deposit contains primarily material indistinguishable from material found on the b...
Shores of eastern Hokkaido rose by perhaps I m a few centuries ago. The uplifted area extended at... more Shores of eastern Hokkaido rose by perhaps I m a few centuries ago. The uplifted area extended at least 50km along the southern Kuril Trench. It included the estuaries Akkeshi-ko and Hichirippu, on the Pacific coast, and Furen-ko and Onneto, which open to the Okhotsk Sea. At each estuary, intertidal and subtidal flats rose with respect to tide level; wetland plants colonized the emerging land; and peaty wetland deposits thereby covered mud and sand of the former flats. Previous work at Akkeshi-ko and Onneto showed that such emergence occurred at least three times in the past 3000 years. Volcanic-ash layers date the youngest emergence to the seventeenth century AD. New evidence from Akkeshi-ko, Hichirippu and Furen-ko clarifies the age and amount of this youngest emergence. Much of it probably dates from the century's middle decades. Some of the newly emerged land remained above high tides into the middle of the eighteenth century or later. The emergence in the last half of the s...
... MCADOO,3 BRUCE JAFFE,4 LORI DENGLER,5 GUY GELFENBAUM,4 BRETWOOD HIGMAN,6 RAHMAN HIDAYAT,7,8,1... more ... MCADOO,3 BRUCE JAFFE,4 LORI DENGLER,5 GUY GELFENBAUM,4 BRETWOOD HIGMAN,6 RAHMAN HIDAYAT,7,8,14 ANDREW MOORE,9 ... in Jakarta preparing to begin a research cruise from Padang in Sumatra, through the islands west of Sumatra, north to Banda ...
The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Isla... more The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Islands on 2 April 2007. That number would have likely been considerably higher were it not for the appropriate reaction of the indigenous coastal populations and a helpful physical geography. Buffering coral reefs reflected some wave energy back to sea, reducing the power of the wave. Hills a short distance behind the coastal villages provided accessible havens. Despite this beneficial physiography, immigrant populations died at disproportionately high rates in comparably damaged areas because they did not recognize the signs of the impeding tsunami. The indigenous population of Tapurai, which lacks a steep barrier reef to reflect the incoming energy, experienced a much more powerful wave, and the population suffered heavy losses. Indigenous knowledge as an integral tool in basin wide tsunami warning systems has the potential to mitigate disasters in the near field. Community-based disaster management plans must be cognizant of educating diverse populations that have different understandings of their environment.
Dams decrease stream gradient and flow velocity, and often trap a stream's sediment load. For 188... more Dams decrease stream gradient and flow velocity, and often trap a stream's sediment load. For 188 years, sedimentation in the Munroe Falls dam pool on the Cuyahoga River, Ohio created a sediment record of both natural and anthropogenic variability. A wooden dam, first constructed in 1817, was replaced with a 3.66-m-high stone dam in 1902 to better serve local industrial needs. Before this dam was removed in 2005, a coring and transect profiling study was undertaken to characterize the dam pool sediments. To a distance of 600 m upstream of the Munroe Falls Dam, only ~30 cm of sediment overlaid the bedrock in the thalweg, indicating that the deep-water channel was an area of sediment transport. However, in the low-velocity shallow-water margins of the dam pool, up to 3 m of organicrich, clayey silt had accumulated above pre-dam floodplain deposits. Past flooding events are recorded in these dam pool sediment deposits by an increase in woody debris and sand. A distinctive lithology having an oily sheen, abundant woody debris, and elevated trace metal concentrations occurs at depth throughout the deposits in the shallow-water margins of the dam pool. 210 Pb dating places the top of this layer at approximately 1918. The 1913 flood in northeast Ohio probably deposited this contaminated layer from washed-out upstream sources. A direct relationship between sediment trace metal (Pb, Zn) and magnetic mineral concentrations demonstrates that magnetic parameters can provide rapid pollution assessment of dam pool sediments.
Journal of Geotechnical and Geoenvironmental Engineering, 2008
Hurricane Katrina ͑August 23-30, 2005͒ was one of the costliest and deadliest hurricanes to ever ... more Hurricane Katrina ͑August 23-30, 2005͒ was one of the costliest and deadliest hurricanes to ever strike the United States, impacting low-lying coastal plains particularly vulnerable to storm surge flooding. Maximum storm surges, overland flow depths, and inundation distances were measured along the Gulf Coast of Florida, Alabama, Mississippi, and Louisiana. The vehicle-based survey was complemented by inspections with the reconnaissance boat along the Gulf Coast and the Mississippi Barrier Islands. The survey covered both the impact on the built and the natural environments. The storm surge peaked to the east of Katrina's path exceeding 10 m in several locations along the Mississippi coastline. The storm surge measurements show that the lower floors of specially designed buildings were damaged by the surge of seawater and associated wave action, while the upper floors sustained minimal wind damage. The storm surge measurements along New Orleans Lakeshore allowed the investigators to exclude overtopping as failure mechanism for the 17th Street outfall canal levee. Hurricane Katrina's storm surge distribution ͑Category 3 at landfall͒ is compared against Hurricane Camille's storm surge distribution ͑Category 5 at landfall͒. The land loss on the barrier islands and the increased vulnerability of the US Gulf Coast to future hurricane storm surges is discussed.
The 17 July 2006 magnitude M w 7.8 earthquake off the south coast of western Java, Indonesia, gen... more The 17 July 2006 magnitude M w 7.8 earthquake off the south coast of western Java, Indonesia, generated a tsunami that effected over 300 km of coastline and killed more than 600 people, with locally focused runup heights exceeding 20 m. This slow earthquake was hardly felt on Java, and wind waves breaking masked any preceding withdrawal of the water from the shoreline, making this tsunami difficult to detect before impact. An International Tsunami Survey Team was deployed within one week and the investigation covered more than 600 km of coastline. Measured tsunami heights and run-up distributions were uniform at 5 to 7 m along 200 km of coast; however there was a pronounced peak on the south coast of Nusa Kambangan, where the tsunami impact carved a sharp trimline in a forest at elevations up to 21 m and 1 km inland. Local flow depth exceeded 8 m along the elevated coastal plain between the beach and the hill slope. We infer that the focused tsunami and runup heights on the island suggest a possible local submarine slump or mass movement.
Recent paleoseismic and geologic studies indicate that a tsunami occurred 1100 years ago in Puget... more Recent paleoseismic and geologic studies indicate that a tsunami occurred 1100 years ago in Puget Sound. This study aims to reproduce and validate the model tsunami, using a finite difference model based on nonlinear shallow water theory and abathymetry/topography computational grid that takes into account the 1-meter rise in sea level that has occurred in the region during the past 1100 years. Estimates of tsunami height, the extent of inundation, and the current velocity pattern are provided at the northern head of Cultus Bay, Whidbey Island, where paleotsunami sand deposits have been found. The model demonstrates that a tsunami generated when the background water level was at mean high water or above could have surged across the then-existing coastal marsh, penetrated the full length of the shallow bay, and deposited the observed sand layers.
Hydraulic reconstruction of paleotsunamis hinges on understanding the relationship between bore s... more Hydraulic reconstruction of paleotsunamis hinges on understanding the relationship between bore size and particle advection length. Although previous studies have shown that a relationship does exist between bore size, particle size, and particle advection length, none have studied the relationship between particle shape, initial orientation and advection length. We performed experiments with nine aluminum rectangular prisms and five aluminum cubes to determine the effect of shape on advection distance. The prisms were sized so that particle volume remained constant while the volume of the cubes varied. Bore height and velocity were held constant. Prisms were placed so that a different face was facing the flow for each experiment. Our results show that, for constant particle volume and density, the advection distance is a function of the axis length along the direction of flow. As the length of the particle axis in the flow direction increases, its advection length decreases. For example, the advection length of a prism with a given plane facing the flow is determined by the length of the third axis. These results suggest that tsunami hydraulic reconstructions based on irregularly shaped objects may depend on the shape factor and on the original orientation of the objects.
This study aims to reproduce the tsunami that occurred 1100 years ago in Puget Sound reported by ... more This study aims to reproduce the tsunami that occurred 1100 years ago in Puget Sound reported by recent paleoseismological studies, using a finite difference model based on nonlinear shallow water theory. The study refines the estimates of run-up height, flow depth, and current velocity at these sites made by Moore (1993) and Dinkelman and Holmes (1993), using a high-resolution model that explicitly allows for coastal flooding and drying. The model is also used to estimate the spatial patterns of tsunami propagation and coastal inundation throughout Puget Sound for this earthquake scenario. When combined with existing field observations of paleotsunamis and ground movement, the simulations will help to constrain the earthquake mechanism. They will also help guide the search for additional geological evidence of this event.
An International Tsunami Survey Team ͑ITST͒ conducted field surveys of tsunami effects on the wes... more An International Tsunami Survey Team ͑ITST͒ conducted field surveys of tsunami effects on the west coast of northern and central Sumatra and offshore islands 3-4 months after the 26 December 2004 tsunami. The study sites spanned 800 km of coastline from Breuh Island north of Banda Aceh to the Batu Islands, and included 22 sites in Aceh province in Sumatra and on Simeulue Island, Nias Island, the Banyak Islands, and the Batu Islands. Tsunami runup, elevation, flow depth, inundation distance, sedimentary characteristics of deposits, near-shore bathymetry, and vertical land movement ͑subsidence and uplift͒ were studied. The maximum tsunami elevations were greater than 16 m, and the maximum tsunami flow depths were greater than 13 m at all sites studied along 135 km of coastline in northwestern Sumatra. Tsunami flow depths were as much as 10 m at 1,500 m inland. Extensive tsunami deposits, primarily composed of sand and typically 5-20 cm thick, were observed in northwestern Sumatra.
Abstract
Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the... more Abstract Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the A.D. 2004 Indian Ocean tsunami and older similar deposits that provide evidence for a tsunami 2417 ± 152 cal. (calendar) yr B.P. to 2925 ± 98 cal. yr B.P., and for six tsunamis between 4064 ± 128 cal. yr B.P. and 6665 ± 110 cal. yr B.P., a period for which the sediment record appears continuous. Radiocarbon dating indicates that the recurrence interval is variable, ranging from 181–517 yr to 1045 ± 334 yr, with a mean recurrence interval of 434 ± 40 yr during the ca. 4000–7000 cal. yr B.P. continuous interval. Assuming that these tsunamis were generated by giant earthquakes along the Sumatra-Andaman subduction zone, a reasonable assumption for this far-field transoceanic location, this record extends the giant-earthquake history for the Indian Ocean region. The longest recurrence interval of more than 1000 yr implies that earthquakes along the subduction zone may reach twice the size of the 2004 earthquake.
The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded ... more The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded coastal southern Java to a depth of at least 8 m and inundated up to 1 km inland. In most places the primarily heavy mineral sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet probably record the passage of up to two individual waves, a point noted in eyewitness accounts. We studied the 2006 tsunami deposits in detail along a flow parallel transect about 750 m long, 15 km east of Cilacap. The tsunami deposit first becomes discernable from the underlying sediment 70 m from the shoreline. From 75 to 300 m inland the deposit has been laid down in rice paddies, and maintains a thickness of 10-20 cm. Landward of 300 m the deposit thins dramatically, reaching 1 mm by 450 m inland. From 450 m to the edge of deposition (around 700 m inland) the deposit remains \1 mm thick. Deposition generally attended inundation-along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. The thicker part of the deposit contains primarily sand indistinguishable from that found on the beach 3 weeks after the event, but after about 450 m (and roughly coinciding with the decrease in thickness) the tsunami sediment shifts to become more like the underlying paddy soil than the beach sand. Grain sizes within the deposit tend to fine upward and landward, although overall upward fining takes place in two discrete pulses, with an initial section of inverse grading followed by a section of normal grading. The two inversely graded sections are also density graded, with denser grains at the base, and less dense grains at the top. The two normally graded sections show no trends in density. The inversely graded sections show high density sediment to the base and become less dense upward and represents traction carpet flows at the base of the tsunami. These are suggestive of high shear rates in the flow. Because of the grain sorting in the traction carpet, the landward-fining trends usually seen in tsunami deposits are masked, although lateral changes of mean sediment grain size along the transect do show overall landward fining, with more variation as the deposit tapers off. The deposit is also thicker in the more seaward portions than would be produced by tsunamis lacking traction carpets.
The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded ... more The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded coastal southern Java to a depth of at least 8 m and inundated up to 1 km inland. In most places the primarily heavy mineral sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet probably record the passage of up to two individual waves, a point noted in eyewitness accounts. We studied the 2006 tsunami deposits in detail along a flow parallel transect about 750 m long, 15 km east of Cilacap. The tsunami deposit first becomes discernable from the underlying sediment 70 m from the shoreline. From 75 to 300 m inland the deposit has been laid down in rice paddies, and maintains a thickness of 10-20 cm. Landward of 300 m the deposit thins dramatically, reaching 1 mm by 450 m inland. From 450 m to the edge of deposition (around 700 m inland) the deposit remains \1 mm thick. Deposition generally attended inundation-along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. The thicker part of the deposit contains primarily sand indistinguishable from that found on the beach 3 weeks after the event, but after about 450 m (and roughly coinciding with the decrease in thickness) the tsunami sediment shifts to become more like the underlying paddy soil than the beach sand. Grain sizes within the deposit tend to fine upward and landward, although overall upward fining takes place in two discrete pulses, with an initial section of inverse grading followed by a section of normal grading. The two inversely graded sections are also density graded, with denser grains at the base, and less dense grains at the top. The two normally graded sections show no trends in density. The inversely graded sections show high density sediment to the base and become less dense upward and represents traction carpet flows at the base of the tsunami. These are suggestive of high shear rates in the flow. Because of the grain sorting in the traction carpet, the landward-fining trends usually seen in tsunami deposits are masked, although lateral changes of mean sediment grain size along the transect do show overall landward fining, with more variation as the deposit tapers off. The deposit is also thicker in the more seaward portions than would be produced by tsunamis lacking traction carpets.
The 17 July 2006 magnitude Mw 7.8 earthquake off the south coast of western Java, Indonesia, gene... more The 17 July 2006 magnitude Mw 7.8 earthquake off the south coast of western Java, Indonesia, generated a tsunami that effected over 300 km of coastline and killed more than 600 people, with locally focused runup heights exceeding 20 m. This slow earthquake was hardly felt on Java, and wind waves breaking masked any preceding withdrawal of the water from the shoreline, making this tsunami difficult to detect before impact. An International Tsunami Survey Team was deployed within one week and the investigation covered more than 600 km of coastline. Measured tsunami heights and run-up distributions were uniform at 5 to 7 m along 200 km of coast; however there was a pronounced peak on the south coast of Nusa Kambangan, where the tsunami impact carved a sharp trimline in a forest at elevations up to 21 m and 1 km inland. Local flow depth exceeded 8 m along the elevated coastal plain between the beach and the hill slope. We infer that the focused tsunami and runup heights on the island su...
bay-mouth bar some 200 m seaward of the deposit. We took approximately 100 core samples of this d... more bay-mouth bar some 200 m seaward of the deposit. We took approximately 100 core samples of this deposit in an attempt to characterize lateral grain size trends within the sand. Although the coarse fraction does fine with distance inland, the fine fraction does not change size over the study area, and the aggregate grain size changes in no systematic way. We interpret this deposit to represent the mixture of material picked up at the bar with material picked up at the gravel shoreline. The bar material does not fine in part because it is already fairly well sorted, but also because it is far from its source. The shoreline material, on the other hand, is poorly sorted so that the tsunami took only those grains it was capable of moving, and deposited them closer to their source. We estimated the size of the tsunami by determining the flow depth-flow velocity combinations required to advect sand from the bar to the back of the deposit, and by estimating the shear velocity required for motion of the largest grain we found during our survey. This modeling indicates an average flow depth of about 2.5-2.8 m over the area, at a flow velocity of 1.9-2.2 m/s. This estimate compares well with eyewitness accounts of a maximum flow depth of 7 m at the shoreline if our estimate represents an average over the whole study area.
Eos, Transactions American Geophysical Union, 2000
Vanuatu is a volcanic archipelago located some 2000 km northeast of Australia, in the heart of Me... more Vanuatu is a volcanic archipelago located some 2000 km northeast of Australia, in the heart of Melanesia. The islands are mainly agricultural, but are also a tourist destination for Australians and New Zealanders, many of whom come to see the active volcanoes on Ambrym and Tanna, and the annual practice of "land diving" on Pentecost. An earthquake estimated between moment magnitude 7.1 and 7.5 occurred off the east coast of Vanuatu on November 26, 1999 at 13:21 UTC-the earthquake generated a damaging tsunami that struck the coast of Vanuatu, where it reached as high as 6.6 meters above sea level and destroyed an entire village (Figures 1 and 2). Remarkably, only 5 people were killed by the tsunami, most likely because the villagers were well informed about tsunamis and their effects. Two weeks after the tsunami, our group spent six days interviewing eyewitnesses to the disaster, surveying damage caused by the waves, and measuring sand and debris left by the tsunami. We hope to use this data to understand the factors that lead to loss of life during a tsunami, to provide benchmark data for computer simulations of tsunamis, and to understand how to identify the traces left by ancient tsunamis. The earthquake and tsunami Vanuatu consists of an island arc formed by the subduction of the Australian plate under the Pacific plate (Figure 2B). Vanuatu is seismically active, with magnitude 5-6 events common, especially in the Central Basin area bounded by Espiritu Santo and Malakula on the west, and Maewo and Pentecost on the east. A magnitude 6.4 event occurred in the central basin in 1965, followed the next day by a magnitude 7.0 earthquake near Epi. A magnitude 7.0 earthquake also occurred in 1981 south of Malakula. Because of Vanuatu's steep topography, landslides commonly accompany earthquakes-these landslides may also occur offshore. Wong and Greene (1988) noted many large submarine landslides in the Central Basin that could have triggered tsunamis. Previous tsunamis occurred in 1875 ("Vanuatu"), 1961 (south of Efate), and 1965, which saw two tsunamis a day apart (the first in the Central
The 2004 Sumatra-Andaman tsunami flooded coastal northern Sumatra to a depth of over 20 m, deposi... more The 2004 Sumatra-Andaman tsunami flooded coastal northern Sumatra to a depth of over 20 m, deposited a discontinuous sheet of sand up to 80 cm thick, and left mud up to 5 km inland. In most places the sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet may record the passage of up to 3 individual waves. We studied the 2004 tsunami deposits in detail along a flow-parallel transect about 400 m long, 16 km southwest of Banda Aceh. Near the shore along this transect, the deposit is thin or absent. Between 50 and 400 m inland it ranges in thickness from 5 to 20 cm. The main trend in thickness is a tendency to thicken by filling low spots, most dramatically at pre-existing stream channels. Deposition generally attended inundation—along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. Although the tsunami deposit contains primarily material indistinguishable from material found on the b...
Shores of eastern Hokkaido rose by perhaps I m a few centuries ago. The uplifted area extended at... more Shores of eastern Hokkaido rose by perhaps I m a few centuries ago. The uplifted area extended at least 50km along the southern Kuril Trench. It included the estuaries Akkeshi-ko and Hichirippu, on the Pacific coast, and Furen-ko and Onneto, which open to the Okhotsk Sea. At each estuary, intertidal and subtidal flats rose with respect to tide level; wetland plants colonized the emerging land; and peaty wetland deposits thereby covered mud and sand of the former flats. Previous work at Akkeshi-ko and Onneto showed that such emergence occurred at least three times in the past 3000 years. Volcanic-ash layers date the youngest emergence to the seventeenth century AD. New evidence from Akkeshi-ko, Hichirippu and Furen-ko clarifies the age and amount of this youngest emergence. Much of it probably dates from the century's middle decades. Some of the newly emerged land remained above high tides into the middle of the eighteenth century or later. The emergence in the last half of the s...
... MCADOO,3 BRUCE JAFFE,4 LORI DENGLER,5 GUY GELFENBAUM,4 BRETWOOD HIGMAN,6 RAHMAN HIDAYAT,7,8,1... more ... MCADOO,3 BRUCE JAFFE,4 LORI DENGLER,5 GUY GELFENBAUM,4 BRETWOOD HIGMAN,6 RAHMAN HIDAYAT,7,8,14 ANDREW MOORE,9 ... in Jakarta preparing to begin a research cruise from Padang in Sumatra, through the islands west of Sumatra, north to Banda ...
The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Isla... more The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Islands on 2 April 2007. That number would have likely been considerably higher were it not for the appropriate reaction of the indigenous coastal populations and a helpful physical geography. Buffering coral reefs reflected some wave energy back to sea, reducing the power of the wave. Hills a short distance behind the coastal villages provided accessible havens. Despite this beneficial physiography, immigrant populations died at disproportionately high rates in comparably damaged areas because they did not recognize the signs of the impeding tsunami. The indigenous population of Tapurai, which lacks a steep barrier reef to reflect the incoming energy, experienced a much more powerful wave, and the population suffered heavy losses. Indigenous knowledge as an integral tool in basin wide tsunami warning systems has the potential to mitigate disasters in the near field. Community-based disaster management plans must be cognizant of educating diverse populations that have different understandings of their environment.
Dams decrease stream gradient and flow velocity, and often trap a stream's sediment load. For 188... more Dams decrease stream gradient and flow velocity, and often trap a stream's sediment load. For 188 years, sedimentation in the Munroe Falls dam pool on the Cuyahoga River, Ohio created a sediment record of both natural and anthropogenic variability. A wooden dam, first constructed in 1817, was replaced with a 3.66-m-high stone dam in 1902 to better serve local industrial needs. Before this dam was removed in 2005, a coring and transect profiling study was undertaken to characterize the dam pool sediments. To a distance of 600 m upstream of the Munroe Falls Dam, only ~30 cm of sediment overlaid the bedrock in the thalweg, indicating that the deep-water channel was an area of sediment transport. However, in the low-velocity shallow-water margins of the dam pool, up to 3 m of organicrich, clayey silt had accumulated above pre-dam floodplain deposits. Past flooding events are recorded in these dam pool sediment deposits by an increase in woody debris and sand. A distinctive lithology having an oily sheen, abundant woody debris, and elevated trace metal concentrations occurs at depth throughout the deposits in the shallow-water margins of the dam pool. 210 Pb dating places the top of this layer at approximately 1918. The 1913 flood in northeast Ohio probably deposited this contaminated layer from washed-out upstream sources. A direct relationship between sediment trace metal (Pb, Zn) and magnetic mineral concentrations demonstrates that magnetic parameters can provide rapid pollution assessment of dam pool sediments.
Journal of Geotechnical and Geoenvironmental Engineering, 2008
Hurricane Katrina ͑August 23-30, 2005͒ was one of the costliest and deadliest hurricanes to ever ... more Hurricane Katrina ͑August 23-30, 2005͒ was one of the costliest and deadliest hurricanes to ever strike the United States, impacting low-lying coastal plains particularly vulnerable to storm surge flooding. Maximum storm surges, overland flow depths, and inundation distances were measured along the Gulf Coast of Florida, Alabama, Mississippi, and Louisiana. The vehicle-based survey was complemented by inspections with the reconnaissance boat along the Gulf Coast and the Mississippi Barrier Islands. The survey covered both the impact on the built and the natural environments. The storm surge peaked to the east of Katrina's path exceeding 10 m in several locations along the Mississippi coastline. The storm surge measurements show that the lower floors of specially designed buildings were damaged by the surge of seawater and associated wave action, while the upper floors sustained minimal wind damage. The storm surge measurements along New Orleans Lakeshore allowed the investigators to exclude overtopping as failure mechanism for the 17th Street outfall canal levee. Hurricane Katrina's storm surge distribution ͑Category 3 at landfall͒ is compared against Hurricane Camille's storm surge distribution ͑Category 5 at landfall͒. The land loss on the barrier islands and the increased vulnerability of the US Gulf Coast to future hurricane storm surges is discussed.
The 17 July 2006 magnitude M w 7.8 earthquake off the south coast of western Java, Indonesia, gen... more The 17 July 2006 magnitude M w 7.8 earthquake off the south coast of western Java, Indonesia, generated a tsunami that effected over 300 km of coastline and killed more than 600 people, with locally focused runup heights exceeding 20 m. This slow earthquake was hardly felt on Java, and wind waves breaking masked any preceding withdrawal of the water from the shoreline, making this tsunami difficult to detect before impact. An International Tsunami Survey Team was deployed within one week and the investigation covered more than 600 km of coastline. Measured tsunami heights and run-up distributions were uniform at 5 to 7 m along 200 km of coast; however there was a pronounced peak on the south coast of Nusa Kambangan, where the tsunami impact carved a sharp trimline in a forest at elevations up to 21 m and 1 km inland. Local flow depth exceeded 8 m along the elevated coastal plain between the beach and the hill slope. We infer that the focused tsunami and runup heights on the island suggest a possible local submarine slump or mass movement.
Recent paleoseismic and geologic studies indicate that a tsunami occurred 1100 years ago in Puget... more Recent paleoseismic and geologic studies indicate that a tsunami occurred 1100 years ago in Puget Sound. This study aims to reproduce and validate the model tsunami, using a finite difference model based on nonlinear shallow water theory and abathymetry/topography computational grid that takes into account the 1-meter rise in sea level that has occurred in the region during the past 1100 years. Estimates of tsunami height, the extent of inundation, and the current velocity pattern are provided at the northern head of Cultus Bay, Whidbey Island, where paleotsunami sand deposits have been found. The model demonstrates that a tsunami generated when the background water level was at mean high water or above could have surged across the then-existing coastal marsh, penetrated the full length of the shallow bay, and deposited the observed sand layers.
Hydraulic reconstruction of paleotsunamis hinges on understanding the relationship between bore s... more Hydraulic reconstruction of paleotsunamis hinges on understanding the relationship between bore size and particle advection length. Although previous studies have shown that a relationship does exist between bore size, particle size, and particle advection length, none have studied the relationship between particle shape, initial orientation and advection length. We performed experiments with nine aluminum rectangular prisms and five aluminum cubes to determine the effect of shape on advection distance. The prisms were sized so that particle volume remained constant while the volume of the cubes varied. Bore height and velocity were held constant. Prisms were placed so that a different face was facing the flow for each experiment. Our results show that, for constant particle volume and density, the advection distance is a function of the axis length along the direction of flow. As the length of the particle axis in the flow direction increases, its advection length decreases. For example, the advection length of a prism with a given plane facing the flow is determined by the length of the third axis. These results suggest that tsunami hydraulic reconstructions based on irregularly shaped objects may depend on the shape factor and on the original orientation of the objects.
This study aims to reproduce the tsunami that occurred 1100 years ago in Puget Sound reported by ... more This study aims to reproduce the tsunami that occurred 1100 years ago in Puget Sound reported by recent paleoseismological studies, using a finite difference model based on nonlinear shallow water theory. The study refines the estimates of run-up height, flow depth, and current velocity at these sites made by Moore (1993) and Dinkelman and Holmes (1993), using a high-resolution model that explicitly allows for coastal flooding and drying. The model is also used to estimate the spatial patterns of tsunami propagation and coastal inundation throughout Puget Sound for this earthquake scenario. When combined with existing field observations of paleotsunamis and ground movement, the simulations will help to constrain the earthquake mechanism. They will also help guide the search for additional geological evidence of this event.
An International Tsunami Survey Team ͑ITST͒ conducted field surveys of tsunami effects on the wes... more An International Tsunami Survey Team ͑ITST͒ conducted field surveys of tsunami effects on the west coast of northern and central Sumatra and offshore islands 3-4 months after the 26 December 2004 tsunami. The study sites spanned 800 km of coastline from Breuh Island north of Banda Aceh to the Batu Islands, and included 22 sites in Aceh province in Sumatra and on Simeulue Island, Nias Island, the Banyak Islands, and the Batu Islands. Tsunami runup, elevation, flow depth, inundation distance, sedimentary characteristics of deposits, near-shore bathymetry, and vertical land movement ͑subsidence and uplift͒ were studied. The maximum tsunami elevations were greater than 16 m, and the maximum tsunami flow depths were greater than 13 m at all sites studied along 135 km of coastline in northwestern Sumatra. Tsunami flow depths were as much as 10 m at 1,500 m inland. Extensive tsunami deposits, primarily composed of sand and typically 5-20 cm thick, were observed in northwestern Sumatra.
Abstract
Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the... more Abstract Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the A.D. 2004 Indian Ocean tsunami and older similar deposits that provide evidence for a tsunami 2417 ± 152 cal. (calendar) yr B.P. to 2925 ± 98 cal. yr B.P., and for six tsunamis between 4064 ± 128 cal. yr B.P. and 6665 ± 110 cal. yr B.P., a period for which the sediment record appears continuous. Radiocarbon dating indicates that the recurrence interval is variable, ranging from 181–517 yr to 1045 ± 334 yr, with a mean recurrence interval of 434 ± 40 yr during the ca. 4000–7000 cal. yr B.P. continuous interval. Assuming that these tsunamis were generated by giant earthquakes along the Sumatra-Andaman subduction zone, a reasonable assumption for this far-field transoceanic location, this record extends the giant-earthquake history for the Indian Ocean region. The longest recurrence interval of more than 1000 yr implies that earthquakes along the subduction zone may reach twice the size of the 2004 earthquake.
The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded ... more The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded coastal southern Java to a depth of at least 8 m and inundated up to 1 km inland. In most places the primarily heavy mineral sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet probably record the passage of up to two individual waves, a point noted in eyewitness accounts. We studied the 2006 tsunami deposits in detail along a flow parallel transect about 750 m long, 15 km east of Cilacap. The tsunami deposit first becomes discernable from the underlying sediment 70 m from the shoreline. From 75 to 300 m inland the deposit has been laid down in rice paddies, and maintains a thickness of 10-20 cm. Landward of 300 m the deposit thins dramatically, reaching 1 mm by 450 m inland. From 450 m to the edge of deposition (around 700 m inland) the deposit remains \1 mm thick. Deposition generally attended inundation-along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. The thicker part of the deposit contains primarily sand indistinguishable from that found on the beach 3 weeks after the event, but after about 450 m (and roughly coinciding with the decrease in thickness) the tsunami sediment shifts to become more like the underlying paddy soil than the beach sand. Grain sizes within the deposit tend to fine upward and landward, although overall upward fining takes place in two discrete pulses, with an initial section of inverse grading followed by a section of normal grading. The two inversely graded sections are also density graded, with denser grains at the base, and less dense grains at the top. The two normally graded sections show no trends in density. The inversely graded sections show high density sediment to the base and become less dense upward and represents traction carpet flows at the base of the tsunami. These are suggestive of high shear rates in the flow. Because of the grain sorting in the traction carpet, the landward-fining trends usually seen in tsunami deposits are masked, although lateral changes of mean sediment grain size along the transect do show overall landward fining, with more variation as the deposit tapers off. The deposit is also thicker in the more seaward portions than would be produced by tsunamis lacking traction carpets.
The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded ... more The 2006 western Java tsunami deposited a discontinuous sheet of sand up to 20 cm thick, flooded coastal southern Java to a depth of at least 8 m and inundated up to 1 km inland. In most places the primarily heavy mineral sand sheet is normally graded, and in some it contains complex internal stratigraphy. Structures within the sand sheet probably record the passage of up to two individual waves, a point noted in eyewitness accounts. We studied the 2006 tsunami deposits in detail along a flow parallel transect about 750 m long, 15 km east of Cilacap. The tsunami deposit first becomes discernable from the underlying sediment 70 m from the shoreline. From 75 to 300 m inland the deposit has been laid down in rice paddies, and maintains a thickness of 10-20 cm. Landward of 300 m the deposit thins dramatically, reaching 1 mm by 450 m inland. From 450 m to the edge of deposition (around 700 m inland) the deposit remains \1 mm thick. Deposition generally attended inundation-along the transect, the tsunami deposited sand to within about 40 m of the inundation limit. The thicker part of the deposit contains primarily sand indistinguishable from that found on the beach 3 weeks after the event, but after about 450 m (and roughly coinciding with the decrease in thickness) the tsunami sediment shifts to become more like the underlying paddy soil than the beach sand. Grain sizes within the deposit tend to fine upward and landward, although overall upward fining takes place in two discrete pulses, with an initial section of inverse grading followed by a section of normal grading. The two inversely graded sections are also density graded, with denser grains at the base, and less dense grains at the top. The two normally graded sections show no trends in density. The inversely graded sections show high density sediment to the base and become less dense upward and represents traction carpet flows at the base of the tsunami. These are suggestive of high shear rates in the flow. Because of the grain sorting in the traction carpet, the landward-fining trends usually seen in tsunami deposits are masked, although lateral changes of mean sediment grain size along the transect do show overall landward fining, with more variation as the deposit tapers off. The deposit is also thicker in the more seaward portions than would be produced by tsunamis lacking traction carpets.
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Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the A.D. 2004 Indian Ocean tsunami and older similar deposits that provide evidence for a tsunami 2417 ± 152 cal. (calendar) yr B.P. to 2925 ± 98 cal. yr B.P., and for six tsunamis between 4064 ± 128 cal. yr B.P. and 6665 ± 110 cal. yr B.P., a period for which the sediment record appears continuous. Radiocarbon dating indicates that the recurrence interval is variable, ranging from 181–517 yr to 1045 ± 334 yr, with a mean recurrence interval of 434 ± 40 yr during the ca. 4000–7000 cal. yr B.P. continuous interval. Assuming that these tsunamis were generated by giant earthquakes along the Sumatra-Andaman subduction zone, a reasonable assumption for this far-field transoceanic location, this record extends the giant-earthquake history for the Indian Ocean region. The longest recurrence interval of more than 1000 yr implies that earthquakes along the subduction zone may reach twice the size of the 2004 earthquake.
Sediment cores from Karagan Lagoon in southeastern Sri Lanka retrieved deposits from the A.D. 2004 Indian Ocean tsunami and older similar deposits that provide evidence for a tsunami 2417 ± 152 cal. (calendar) yr B.P. to 2925 ± 98 cal. yr B.P., and for six tsunamis between 4064 ± 128 cal. yr B.P. and 6665 ± 110 cal. yr B.P., a period for which the sediment record appears continuous. Radiocarbon dating indicates that the recurrence interval is variable, ranging from 181–517 yr to 1045 ± 334 yr, with a mean recurrence interval of 434 ± 40 yr during the ca. 4000–7000 cal. yr B.P. continuous interval. Assuming that these tsunamis were generated by giant earthquakes along the Sumatra-Andaman subduction zone, a reasonable assumption for this far-field transoceanic location, this record extends the giant-earthquake history for the Indian Ocean region. The longest recurrence interval of more than 1000 yr implies that earthquakes along the subduction zone may reach twice the size of the 2004 earthquake.