Scientific understanding of earthquakes in the New Madrid seismic zone has advanced greatly in recent years, but these advances have resulted in neither better assessment of seismic hazard and risk nor better mitigation policy. The main reasons for this are (1) misunderstanding about the National Seismic Hazard Maps and (2) confusion about seismic hazard and risk. Seismic hazard and seismic risk are two fundamentally different concepts, even though they have often been used interchangeably. Both are used differently in policy decision making, but seismic risk is the deciding factor, not seismic hazard. Even though the input parameters are scientifically sound, we contend that the National Seismic Hazard Maps produced for the New Madrid region are flawed because they were produced from probabilistic seismic hazard analysis (PSHA). PSHA is scientifically flawed: As a complex computer model, it could not pass a simple sensitivity test with a single input earthquake, and the annual probability of exceedance (i.e., exceedance probability in one year and a dimensionless quantity) has been erroneously interpreted and used as the annual frequency or rate of exceedance (i.e., the number of event exceedances per year and a dimensional quantity). Thus, the seismic hazard and resulting seismic risk estimates from PSHA can be viewed as artifacts, and the mitigation policies developed, the NEHRP (National Earthquake Hazards Reduction Program) provisions and resulting building codes in particular, are problematic. Scenario seismic hazard analysis is a more appropriate approach for seismic hazard assessment, seismic risk assessment, as well as policy development in the New Madrid region.

Abstract Factors that influence fluvial sediment discharge in warm climates (catchment-basin size, relief, gradient, tectonic setting, bedrock lithology, and rainfall) can readily be evaluated in fluvial systems of Indonesia. In equatorial Sumatra and Seram, rainfall, catchment-basin size, relief, and gradient are similar, whereas bedrock geology and tectonic setting differ. The relief and rainfall in equatorial Borneo is similar to that of Sumatra and Seram, but gradient, catchment-basin size, and tectonic setting differ. All factors, except rainfall, are very similar for Timor and Seram. A pronounced dry season in Timor and Java distinguish those islands from the wet climates of Seram and Sumatra, respectively. The nature of stream channels (braided or meandering), stream bed materials, the degree of fluvial estuarine fill, deltas, and the nature of coastlines were used to evaluate sediment discharge. In addition, reconnaissance-level stream sampling was conducted for solid-suspended-sediment concentrations, solute concentrations, and pH in rivers in equatorial regions in Sumatra and Borneo, in Seram at 3° S, in Irian Jaya at 4° S, and in West Timor at 10° S. Rainfall in Sumatra, Borneo, and Seram exceeds evapotranspiration for all months of the year (> 100 mm/month and > 2.4 m/yr, perhumid climate). In contrast, in Timor 85 percent of all rainfall (1.4 m/yr) occurs during a four-month rainy season (dry subhumid climate). The absence of a fluvially derived bed load, river-mouth deltas, the lack of fluvial fill of estuaries, and mud-dominated coastal zones in the perhumid regions are indicative of a very low fluvial sediment discharge. Very low sediment concentrations (10 mg/l suspended and 10 mg/l solute) in modern rivers in the perhumid equatorial region of Indonesia are consistent with this observation. In contrast, sediment discharge in dry subhumid climates of Indonesia is very high, as indicated by coarse-grained braided-stream bed materials with cobbles transported to the coast, the complete fluvial fill of estuaries, the formation of river-mouth deltas, and coarse-grained beaches. Very high sediment concentrations (2100 mg/l suspended and 340 mg/l dissolved) during rainy-season discharge in modern rivers in dry-subhumid regions of Indonesia (Timor) are consistent with this observation. The dominant variable affecting fluvial sediment discharge among the islands of Indonesia, therefore, appears to be the degree of seasonality in rainfall regardless of tectonic setting, relief, or catchment-basin size. Solute concentrations in humid and perhumid climates are indicative of bedrock geology. Chemical weathering of massive Miocene limestone thrust sheets in high mountainous areas of Seram and Irian Jaya results in solute concentrations that approximate the solubility of calcite (∼ 50 mg/l). Humid and perhumid areas without significant limestone bedrock geology have solute concentrations that approximate that of rainwater (∼ 10 mg/l).

Recent sedimentation patterns in the central Sumatra basin, Republic of Indonesia, may help to explain the cyclic stratigraphy of the Pennsylvanian System of the eastern United States. Modern influx of fluvial siliciclastic sediment to the epeiric seas of the Sunda shelf, including the Strait of Malacca, appears to be highly restricted by rain forest cover within the ever-wet climate belt of equatorial Sumatra. As a result, much of the marine and estuarine environments appear to be erosional or nondepositional except for localized deposition of sediment in slack water areas, such as the down-stream end of islands. Contemporaneously, thick (>13 m), laterally extensive (>70,000 km 2 ), peat deposits are forming on poorly drained coastal lowlands. Modern peat formation in this study, therefore, is not coeval with aggrading fluvial siliciclastic systems, a situation that commonly is assumed in many depositional models of coal formation. The stratigraphy of Pleistocene and Holocene sediments on the Sunda shelf, as well as those of the Pennsylvanian System, appears to be better explained by the allocyclic controls of climate and sea-level change on sediment flux rather than by depositional models that are based on autocyclic processes. The objective of this paper is to evaluate allocyclic and autocyclic controls on sedimentation in an epeiric setting in a humid (ever-wet) tropical region. Of particular interest are the factors that control peat formation and siliciclastic sediment flux in rivers, estuaries, and open marine environments.

The inorganic geochemistry of three domed ombrogenous peat deposits in Riau and West Kalimantan provinces, Indonesia, was investigated as a possible modern analogue for certain types of low-ash, low-sulfur coal. Mineral matter entering the deposits is apparently limited to small amounts from the allogenic sources of dryfall, rainfall, and diffusion from substrate pore water. In the low-ash peat in the interior of the deposits, a large portion of the mineral matter is authigenic and has been mobilized and stabilized by hydrological, chemical, and biological processes and conditions. Ash yield and sulfur content are low through most of the peat deposits and average 1.1% and 0.14%, respectively, on a moisture-free basis. Ash and sulfur contents only exceed 5% and 0.3%, respectively, near the base of the deposits, with maximum concentrations of 19.9% ash and 0.56% sulfur. Peat water in all three deposits has a low pH, about 4 units, and low dissolved cation concentration, averaging 14 ppm. Near the base, in the geographic interior of each peat deposit, pH is about two units higher and dissolved cation concentration averages 110 ppm. Relative concentrations of the inorganic constituents vary, resulting in chemical facies in the peat. In general, Si, Al, and Fe are the abundant inorganic constituents, although Mg, Ca, and Na dominate in the middle horizon in the geographic interior of coastal peat deposits. The composition of the three deposits reported in this paper indicates that domed ombrogenous peat deposits will result in low ash and sulfur coal, probably less than 10% ash and 1% sulfur, even if marine rocks are laterally and vertically adjacent to the coal.

Peat deposits cover 48,000 km 2 on the lowlands of Riau Province, Sumatra, Indonesia. Two areas containing typical dome-shaped peat deposits were selected for study. These peat deposits are topographically highest in the geographic interior of the deposit and are drained radially outward by blackwater streams. The source of the water in the peat is precipitation, which exceeds evapotranspiration throughout the year. In cross section, the peat deposits are biconvex; they rest on a nearly level surface, which is within a few meters of sea level. The peat accumulated in the past 5,000 years after stabilization of sea level following the rapid sea-level rise during glacial retreat. In the interior area of the peat deposits, the initial peat accumulation rate was rapid (4–5 mm/yr) for approximately 1,000 years; the rate decreased to less than 2 mm/yr for the past 3,500–4,000 years. These peat deposits have a fibric to hemic texture with slight to moderate humification, a low ash yield, and a low sulfur content; and they contain acid water. A thin layer at the bottom of the deposits tends to be more sapric in texture, more humified, higher in ash yield, higher in sulfur content, and less acid than the overlying peat. Proximate and ultimate analyses of a suite of samples from the interior of each peat deposit show no significant differences in peat quality between the Siak Kanan and Bengkalis Island peat deposits. A primary goal of this study was to evaluate peat resources. The 6.6 × 10 9 m 3 of peat in the Siak Kanan peat deposit and 3.0 × 10 9 m 3 of peat in the Bengkalis Island peat deposit constitute a significant fuel resource. This resource study has contributed a three-dimensional framework and peat quality data that can provide insight into the earliest stage of certain types of coal formation.

Analyses of modern Indonesian peat samples reveal that the optical characteristics of peat constituents are consistent with the characteristics of macerals observed in brown coal and, as found by previous workers, brown-coal maceral terminology can be used in the analysis of modern peat. A core from the margin and one from near the center of a domed peat deposit in Riau Province, Sumatra, reveal that the volume of huminite macerals representing well-preserved cell structures (red, red-gray, and gray textinite; ulminite; and corpo/textinite) decreases upward. Huminite macerals representing severely degraded (<20 microns) cellular debris (degraded textinite, attrinite, and densinite) increase uniformly from the base to the surface. Greater degradation of the huminite macerals in the upper peat layers in the interior of the deposit is interpreted to be the result of fungal activity that increased in response to increasingly aerobic conditions associated with the doming of the peat deposit. Aerobic conditions concurrent with the activities of fungi may result in incipient oxidation of the severely degraded huminite macerals. This oxidation could lead to the formation of degradosemifusinite, micrinite, and macrinite maceral precursors in the peat, which may become evident only upon coalification. The core at the margin was petrographically more homogeneous than the core from the center and was dominated by well-preserved huminite macerals except in the upper 1 m, which showed signs of aerobic degradation and was similar to the upper 1 m of the peat in the interior of the deposit. The Stockton and other Middle Pennsylvanian Appalachian coal beds show analogous vertical trends in vitrinite maceral composition. The succession from telocollinite-rich, bright coal lithotypes in the lower benches upward to thin-banded/matrix collinite and desmocollinite in higher splint coal benches is believed to reflect a progression similar to that from the well-preserved textinite macerals in the lower portions of the peat cores to severely fragmented and degraded cellular materials (degraded textinite, attrinite, and densinite) in the upper portions of the cores. This petrographic sequence from bright to splint coal in the Stockton and other Middle Pennsylvanian coal beds supports previous interpretations of an upward transition from planar to domed swamp accumulations.

Two peat cores and one substrate core were collected from the Siak Kanan domed peat deposit in Riau Province, eastern Sumatra, Indonesia. The peat cores consisted of a 9.5-m core from the subaerial part of the domed peat and a 0.51-m core from the bottom of a lake located within the dome. Approximately 1.0 m of substrate material was obtained from a core from the bottom of the lake adjacent to the lacustrine peat core. Samples from selected intervals from the peat cores and from the underlying mineral substrate were low-temperature ashed and examined using light-optical, cathodoluminescent, and scanning electron microscopy, as well as by energy-dispersive X-ray analysis to chemically characterize the inorganic constituents. In addition, some of the ashed samples were analyzed by inductively coupled plasma-atomic emission spectroscopy and Fourier-transform infra-red spectrometry techniques. The low-temperature ash (LTA) of the peat samples is composed of discrete grains of biologic origin and volcanic eolian origin and aggregates of micrometer to submicrometer-sized particles that are largely artifacts of low-temperature ashing. Most of the aggregate material, which makes up approximately 90% of the LTA, probably results from reactions between organically bound cations and S and N which produce sulfate and nitrate compounds. All the Na, Ca, and Mg, and most of the K and the Al in the peat are concentrated in the aggregate fraction. The sulfate and the nitrate salts are readily soluble in water. Different suites of siliceous organisms that may have potential for environmental indicators are present in the lacustrine and domed peat intervals. In addition, rare but identifiable volcanic constituents are present in the samples of all the peat intervals. The volcanic constituents include glass shards, feldspars, zircons, and blue luminescent quartz. Most of the quartz grains from intervals of samples from the lake peat luminesce, however, in the orange plus blue range, which is indicative of a metamorphic origin. Phytoliths and siliceous organisms from samples of both the peats and the substrate intervals did not luminesce in the visible range, which is a characteristic of authigenic quartz and, apparently, biogenic silica. Biogenic silica grains, quartz grains, and other silicate minerals observed in the peat have etching features that may be caused by simple dissolution or interactions with multiple types of multiprotic organic acids. Dissolution and precipitation features are visible on quartz grains from the mineral substrate samples immediately below the peats.

Sulfur is an analyte of considerable importance to the complete major element analysis of ash from low-sulfur, low-ash Indonesian peats. Most analytical schemes for major element peat- and coal-ash analyses, including the inductively coupled plasma atomic emission spectrometry method used in this work, do not permit measurement of sulfur in the ash. As a result, oxide totals cannot be used as a check on accuracy of analysis. Alternative quality control checks verify the accuracy of the cation analyses. Cation and sulfur correlations with percent ash yield suggest that silicon and titanium, and to a lesser extent, aluminum, generally originate as minerals, whereas magnesium and sulfur generally originate from organic matter. Cation correlations with oxide totals indicate that, for these Indonesian peats, magnesium dominates sulfur fixation during ashing because it is considerably more abundant in the ash than calcium, the next most important cation in sulfur fixation.

The Holocene Mahakam River delta, Kalimantan, Indonesia, is a complex fluvial-and tidal-influenced regime prograding into the Makassar Strait. Three plant communities are segregated and controlled by salinity and edaphic conditions. Salt-tolerant mangrove taxa pioneer the lower delta plain tidal flats and are quickly replaced by Nypa palms. These palms comprise the vast majority of dense swamps in the delta plain. A more diverse hardwood forest replaces Nypa swamps when sediments have accumulated to subaerial heights where better drainage is possible. The interior of the island supports well-established primary tropical forest. Autochthonous peat deposits have not been identified in the region. Fluvial distributary channels are the principal conduits through which plant parts originating in these communities are transported to the delta front. Plant parts that reach the delta front may remain resident at the sediment-water interface until they are reworked into accumulations, as thick as 2.5 m, onlapping the interdistributary lower delta plain tidal flats. These allochthonous peat bodies are composed of fragmented canopy detritus from various sources, but mainly from dicotyledonous angiosperms. Plant parts include leaves, cuticles, wood fragments, petiole parts (both dicotyledonous angiosperm and monocotyledonous Nypa ), damar (dipterocarp resins), fruits, and seeds. Deposits occur as high-tide beach ridges. Peat beach ridges alternate with tidal mud flats as the headlands aggrade into the Makassar Strait. Geochemical analyses have been conducted on the peat recovered in bulk samples and from core. These include 14 C dating, Total Organic Content (TOC), bulk sulfur content, Rock-Eval pyrolysis, Py-GC and Py-GCMS. Peat is Holocene (Recent) in origin, with 14 C dates of bulk samples as old as 1050 yr B.P. Damars recovered from the beaches are also Recent in origin (2645 ± 215 yr B.P.; 930 ± 205 yr B.P.). TOC ranges from 27.5%–39.4% with accompanying hydrogen indice (HI) varying from 250–450. Sulfur ranges from 0.65%–2.75%. H/C ratios average 1.43, and O/C ratios average 0.44. The occurrence of relatively high values of the HI are probably due to the incorporation of pieces of Recent damar which exhibit HI as high as 1,130.

Four compositional groups, based on the independent parameters of ash yield, sulfur forms, palynology, petrography, and low-temperature ash mineralogy are recognized in the Stockton and Fire Clay coal beds (Kanawha Formation, Middle Pennsylvanian) from the central Appalachian Basin. The four compositional groups are (1) an arboreous lycopod-dominant group, defined by high percentages of Lycospora and vitrinite (telocollinite), generally low but variable ash yield and sulfur content, and a mixed illite-kaolinite-quartz low-temperature ash mineralogy; (2) a transitional group defined by a mixture of lycopods (arboreous and “herbaceous” forms) and ferns, increased percentages of inertinite and desmocollinite (degraded vitrinite), low ash yield and sulfur content, and an increasingly dominant kaolinite ash mineralogy; (3) an “herbaceous” lycopod and fern group defined by high percentages of Densosporites (and related crassicingulate taxa) and ferns, high inertinite and desmocollinite contents, very low ash yield and sulfur content, and a kaolinite-dominant mineralogy; and (4) a mixed group defined by a palynoflora co-dominated by arboreous and “herbaceous” lycopods and ferns, with catamite and cordaites occurring in increased percentages, and variable petrography. Typically, this group is high in ash yield, low in sulfur content, and has an illite-dominant ash mineralogy. The vertical arrangement of these groups define compositional cycles, which are believed to represent different developmental stages of a domed peat swamp. The commonly observed vertical profile of Lycospora /vitrinite-rich coal layers changing upward to fern-, small lycopod-, and inertinite-rich coal layers defines the first half of the cycle. A return, gradual or abrupt, to Lycospora /vitrinite-rich coal layers toward the top of the bed defines the second half of the cycle. The first half of the cycle is interpreted to represent a progressive change from more planar to more domed peat conditions. This change is marked by increased exposure to air and oxygenated rain water and the establishment of floral seres. The second half of the cycle is interpreted to represent a change from more domed to more planar conditions. Compositional “half cycles,” common in both the Fire Clay and Stockton coal beds, are usually the result of cycle truncation by inorganic partings. Both planar and domed swamp environments contribute to peat formation in modern domed peat systems. Similarly, both of these environments are recognized in the Fire Clay and Stockton coal beds. A majority of these two coal beds are believed to have been derived from planar, to perhaps moderately domed, peat environments. In contrast, a relatively small part of these beds are thought to have been significantly domed.

Coal-ball peats and miospore floras were sampled quantitatively in profiles from the upper Middle Pennsylvanian Springfield Coal of the Illinois Basin. Coal profiles for miospore analysis were sampled at 13 sites, forming two transects across the Galatia paleochannel. Miospore assemblages near paleochannels differ from those near the coal margin. Near the Galatia paleochannel, four species of tree-fern spores ( Laevigatosporites globosus, L. minimus, Punctatosporites minutus, Thymospora pseudothiessenii) share dominance throughout the profile, and Lycospora is subdominant. In profiles near the coal margin, T. pseudothiessenii dominates the lower three-fourths of the seam, and Laevigatosporites globosus dominates the upper one-fourth of the seam. Lycospora is at its most abundant in the lower one-fourth of the coal, and Anacanthotriletes spinosus is abundant in the middle of the seam. Three coal-ball profiles were collected in conjunction with miospore profiles to compare species abundance in the two records. Lycopods are the dominant biovolume producers in coal-ball floras, and tree ferns usually rank second. This differs from the miospore floras, in which tree-fern miospores are dominant over those of lycopods. Disparities between the two records were evaluated with R-values, ratios of percent abundance of species in the miospore record to that in the coal-ball record. In the Springfield Coal, tree ferns are 2 to 3 times and lepidodendrid lycopods 0.5 to 0.75 times as abundant in the miospore record as in the peat. Sigillaria and Diaphorodendron, however, are much more poorly represented by spores and have R-values less than 0.2. Although R-values are too variable among zones in profiles to accurately reconstruct the peat, they provide an estimate of how over- or underrepresented species are in the miospore record and should be considered when estimating vegetational biomass from percent miospore abundance.

The basis of modern fresh-water peatland (mire) classification, namely ground-water influence and source of ionic input, has been adopted in this study for ancient mire analysis. Trends that result from a modern mire’s evolution from a rheotrophic (ground-water influenced) planar to ombrotrophic (solely rain-fed), raised status, under decreasing influence of ground water, include decreasing pH levels, nutrient/ionic supply, ash content, species diversity, and ratio of arboreous to herbaceous vegetation. These attributes are inferred to give rise to the following upward trends within a coal seam: enhanced preservation and reduced biochemical geliflcation within similar tissues; decreasing abundance of liptinite macerals of aquatic affinity, sulfur (especially pyritic) content, and waterborne ash; and decreasing floral diversity. Reversals in these trends may signal change in the trophic status of the ancestral mire (e.g., deflation). The identification of such trends relies heavily upon the description of vitrinite in terms of relative geliflcation. The significance of Eh and the historical use of inertinite in paleomire analysis is questioned. The ancestral mire of the Westphalian B No. 3 seam of the Springhill coalfield, Cumberland Basin, Nova Scotia, formed between a piedmont of coalesced, retreating alluvial fans and the medial reaches of a basin-axis channel belt. The lithologically distinct piedmont, inner mire, and riverine zones of the seam reflect this geomorphic setting. Modeling of a maceral-based index of ground-water influence (strongly gelified tissues and mineral matter versus well preserved tissues) led to the deduction that the paleomire originated as a rheotrophic, and presumably planar, ecosystem that evolved progressively toward a less ground-water-influenced (mesotrophic) state, and possibly to an ombrotrophic, weakly domed system within the inner mire. This maceral-based method suggests a succession of mire types from swamp to fen (and questionably to bog) representing the classic hydroseral succession that forms by the autogenic process of terrestrialization. Contrary to the maceral-based evidence of progressive, albeit weak, raising of the mire surface, ash, sulfur, and miospore diversity increase, and lithotypes become duller upward within the upper third of the seam in the inner zone, suggesting that the mire may have ultimately reverted to a more ground-water-influenced state. A decrease in pH, inferred from an upward increase in tissue structure and decrease in geliflcation, accompanied inner mire development; elsewhere conditions were less acidic. The paleomire flora was dominated throughout by the arboreous lycopsids Lepidodendron hickii and Anabathra (cf. Paralycopodites ), confirming the rheotrophic nature of the ecosystem and the prevalence of flooded conditions. Floral succession of these arboreous lycopsids is evident within the inner mire. Groundwater discharge from alluvial fans at the piedmont margin favored conditions for the colonization of the forest flora. The feedback mechanism of lateral or upslope paludification was aided by the rapid, noncompetitive growth strategy of the arboreous lycopsids. At the riverine margin, autogenic evolution of the ecosystem was stymied by allogenic fluvial processes and by differential compaction about entombed multistory sandstone bodies. Lithotype trends record a general, but similar history of mire development. The ultimate demise of the mire is ascribed to allogenic change, potentially involving precession-induced climate change in concert with basin subsidence and sediment supply.

Cyclic laminations in gray shales are noted above many major coal seams in the Illinois Basin. These features, which are termed “tidal rhythmites,” indicate significant tidal influence during deposition of the roof strata. Many existing models, however, suggest fluvial dominance and crevasse splay deposition for such gray shales. Based on sedimentological and paleogeographical considerations, appropriate deposition models require micro- to mesotidal environments, limited wave reworking, and a mud-dominated, tropical setting. Following these requirements, tidally influenced estuarine/deltaic models can be generated for roof strata of many Illinois Basin coals. This model is based upon modern mud-rich tidally influenced estuaries and deltas in near equatorial settings and can be used to explain occurrence of shales that lack obvious marine influence (based upon paleontology) above low-sulfur coals in the Illinois Basin.