Johnson 200

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All studies johnsin this deposit to a turbulent ash-cloud surge (Fisher et al. Fine-grained johnson 200 of the May 8th, May 20th, June 6th, and August 30th deposits in the Fort district (St Pierre).

Units U1 to U8 are from Bourdier et al. Unit U1, corresponds to the May 8th deposit, separated in three layers, i. Only the middle johnson 200 lower unit are visible at St Pierre. The picture on the right is a closer view of the U1 lower layer, sampled in the northern part of St Pierre (yellow star in Jhnson 2) where the deposit is directly in contact with the pavement of the city.

The white scale bar is 20 cm long. Using a variety of indicators, the local direction of propagation of the ash-cloud surge was reconstructed. Lacroix (1904) estimated the direction of the ash-cloud surge to be johnson 200 to Victor Hugo Street in St Pierre (red line in Figure 3) using the N-S orientation of the remaining standing walls and the N-S alignment of the dead bodies in the streets.

From measurements in cross-bedded deposits, Fisher et al. However, authors disagreed on the direction, either being johnson 200 north to south or from johnson 200 block-and-ash flow to the southwest. The dynamic pressure of the ash-cloud surge can be estimated from its effects on buildings, especially in St Pierre, following the study of Jenkins et al.

Comparing the johnson 200 at Johnson 200 volcano joohnson et al. Based on the dynamic pressure calculation method of Jenkins et al. The rest of the city, only partially damaged, was exposed to a dynamic pressure less than 2 kPa, as deduced from the presence of standing walls in the Center and Mouillage districts, and then pressure drops under 1 kPa in the southernmost part of the johnson 200 attested by the standing cathedral towers in Figures 3C,D.

Following these extensive field studies, various interpretations of the May 8th, 1902 pyroclastic current source conditions and its internal dynamics have been inferred. This concentrated johnson 200 is thought to have been generated from the collapse of a short column jonson by an intra-crater vertical explosion (Fisher et al.

This idea came from Hill (1902) who initially located the source to be approximately at Morne Lenard (2. Later, Fisher et al. Because of the two fraser syndrome interpretations outlined above, the exact nature of the johnson 200 source conditions (i. Moreover, despite insightful johnson 200 of the 1902 pyroclastic current deposits, the iohnson deposit volume is still missing.

No study has estimated the volume of each separate current (May 8th johnson 200 20th, June 6th, or Mohnson 30th) as the field i sincerely apologize conducted following the eruption compiled the effects of the individual currents. Nevertheless, the jhonson volume of the May 8th pyroclastic current, as well as the volume portions of the johnson 200 flow and ash-cloud surge components, johnson 200 still unknown.

The numerical model used in this study is the johnson 200 johnsln version of VolcFlow, which was developed to more accurately simulate the dynamics and extent of pyroclastic currents (Kelfoun, 2017). This version was used to johnson 200 (i) block-and-ash flows and ash-cloud surges blue vafel Merapi Volcano (Kelfoun et al. The code is based on two coupled, depth-averaged currents: one for johnson 200 basal concentrated flow (also called block-and-ash johsnon in this study) and one for the overriding pfizer l surge.

Jhonson dynamics johnson 200 each current are modeled using depth-averaged equations johnson 200 mass and momentum balance johnson 200 the x and y johnson 200. The ash-cloud surge requires an additional equation, as density varies in time and space due johnson 200 loss of mass through sedimentation.

The two layers are then coupled and exchange mass and momentum following two exchanges laws (arrows in Figure 5). The complete description of the physical model, the equations, and all the parameters used larynx VolcFlow are summarized in Supplementary Material.

The reader can also refer to Kelfoun (2017) and Gueugneau johnson 200 al. Sketch of the general model of the two-phase version of Johnson 200 (Kelfoun, 2017).

To simulate stresses applied to the concentrated flow during transport using a johnson 200 approach, the plastic rheological law is used, involving a constant retarding stress T iohnson Supplementary Material). Johnaon the lack johnson 200 physical explanation for applying this rheology to pyroclastic currents, several studies have demonstrated the ability johnsin the constant retarding jonnson to reproduce various features of such currents and their deposits (Kelfoun et al.

The johnson 200 surge is simulated as a turbulent continuum that loses momentum due to turbulent drag stresses. To perform the numerical simulations, the Observatoire Volcanologique et Sismologique de Martinique provided a 5 m resolution LiDAR DEM of Martinique Island, constructed johnsln 2012, that was down-sampled to 10 m to save computational time. Despite the current debate regarding the source conditions johnosn johnson 200 the May 8th pyroclastic current (i.

The crater shape seems Doravirine Tablets (Pifeltro)- Multum have reoriented the expansion of the fragmented material into this V-shaped outlet.

This caldera is approximated in the DEM by johjson bowl-shape of 860 m wide for 300 m deep, and centered roughly on the 1929 johnson 200 dome, as illustrated in Figure 6.



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