scholarly journals Tsunami heights and limits in 1945 along the Makran coast estimated from testimony gathered seven decades later in Gwadar, Pasni and Ormara

2021 ◽  
Author(s):  
Hira Ashfaq Lodhi ◽  
Shoaib Ahmed ◽  
Haider Hasan

Abstract. The towns of Pasni and Ormara were the most severely affected by the 1945 Makran tsuami. The water inundated almost a kilometer at Pasni, engulfing 80 % huts of the town while at Ormara tsunami inundated two and a half kilometers washing away 60 % of the huts. The plate boundary between Arabian plate and Eurasian plate is marked by Makran Subduction Zone (MSZ). This Makran subduction zone in November 1945 was the source of a great earthquake (8.1 Mw) and of an associated tsunami. Estimated death tolls, waves arrival times, extent of inundation and runup remained vague. We summarize observations of tsunami through newspaper items, eye witness accounts and archival documents. The information gathered is reviewed and quantized where possible to get the inundation parameters in specific and impact in general along the Makran coast. The quantization of runup and inundation extents is based on a field survey or on old maps.

2021 ◽  
Vol 21 (10) ◽  
pp. 3085-3096
Author(s):  
Hira Ashfaq Lodhi ◽  
Shoaib Ahmed ◽  
Haider Hasan

Abstract. The towns of Pasni and Ormara were the most severely affected by the 1945 Makran tsunami. The water inundated land for almost 1 km at Pasni, engulfing 80 % of the huts of the town, while at Ormara the tsunami inundated land for 2.5 km, washing away 60 % of the huts. The plate boundary between the Arabian Plate and Eurasian Plate is marked by Makran subduction zone (MSZ). This Makran subduction zone in November 1945 was the source of a great earthquake (8.1 Mw) and an associated tsunami. Estimated death tolls, waves arrival times, and the extent of inundation and runup have remained vague. We summarize observations of the tsunami through newspaper items, eyewitness accounts and archival documents. The information gathered is reviewed and quantified where possible to obtain the inundation parameters specifically and understand the impact in general along the Makran coast. The quantification of runup and inundation extents is based on a field survey or old maps.


Author(s):  
A. Safari ◽  
A. M. Abolghasem ◽  
N. Abedini ◽  
Z. Mousavi

Makran subduction zone is one of the convergent areas that have been studied by spatial geodesy. Makran zone is located in the South Eastern of Iran and South of Pakistan forming the part of Eurasian-Arabian plate's border where oceanic crust in the Arabian plate (or in Oman Sea) subducts under the Eurasian plate ( Farhoudi and Karig, 1977). Due to lack of historical and modern tools in the area, a sampling of sparse measurements of the permanent GPS stations and temporary stations (campaign) has been conducted in the past decade. Makran subduction zone from different perspectives has unusual behaviour: For example, the Eastern and Western parts of the region have very different seismicity and also dip angle of subducted plate is in about 2 to 8 degrees that this value due to the dip angle in other subduction zone is very low. In this study, we want to find the best possible value for parameters that differs Makran subduction zone from other subduction zones. Rigid block modelling method was used to determine these parameters. From the velocity vectors calculated from GPS observations in this area, block model is formed. These observations are obtained from GPS stations that a number of them are located in South Eastern Iran and South Western Pakistan and a station located in North Eastern Oman. According to previous studies in which the locking depth of Makran subduction zone is 38km (Frohling, 2016), in the preparation of this model, parameter value of at least 38 km is considered. With this function, the amount of 2 degree value is the best value for dip angle but for the locking rate there is not any specified amount. Because the proposed model is not sensitive to this parameter. So we can not expect big earthquakes in West of Makran or a low seismicity activity in there but the proposed model definitely shows the Makran subduction layer is locked.


2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohammad Mokhtari ◽  
Ahmad Ala Amjadi ◽  
Leila Mahshadnia ◽  
Mandana Rafizadeh

Abstract The Makran Accretionary Wedge (900 km across) is a consequence of northward subduction of the oceanic part of the Arabian Plate beneath the Lut and Afghan blocks in the northwestern Indian Ocean. It has a complicated tectonic setting as it is located at a triple junction with the Indian Plate. Thick sedimentary layers, a shallow angle of the subducting slab and a large width of the subduction zone, ca. 500–600 km from volcanic arc to active wedge front, are some of the foremost and distinctive characteristics of the Makran Subduction Zone (MSZ). The MSZ is likely divided into at least two segments: the west and the east possibly separated by a sinistral fault known as the Sonne Fault. A division is also inferred from seismicity as it is higher in the east when compared to the west. With the exception of a notable trench, all other characteristics of an accretionary prism observed in well-studied subduction zone can be identified or inferred in the Makran. Three long seismic profiles of the western Makran (200 km long each, with shot points interval of 20 km and receivers interval of 700 m) have recently been acquired. Using these datasets, improved structural/velocity models for the western Makran were developed. This review aims to contribute to achieving a better understanding of the seismotectonic setting and dynamics of the Makran Subduction Zone as it feeds to a refined understanding of the tsunami hazard in the region.


2020 ◽  
Vol 5 (1) ◽  
pp. 01-05
Author(s):  
Muhammad Imran Hafeez Abbasi

Makran Subduction Zone (MZS) is important as this region lies on both sides of the border of Iran and Pakistan along the coastline. Makran Subduction complex has pervasive seismicity and diverse focal mechanism solutions and being in the vicinity of Triple Junction where three major Tectonic plates; Arabian, Eurasian and Indian plates are connecting. Both of Chabahar and Gwadar ports are located in this vicinity, on which China is investing for CPEC, Belt and Road Initiative. The whole world is looking at these projects of Makran, as this may define and transform the future of trade. Hence Geoscience point of view is notable as well in consideration for the successful execution of these projects. Several Microplates/blocks have been proposed around the vicinity MSZ and Indian-Eurasian Plate boundary including the Ormara microplate, Lut Block, Helmand Block, and Pakistan-Iran Makran microplate (PIMM). The purpose of this review is to shed light on PIMM. Despite previous researches related to Makran, still many researchers are working to solve puzzles related to the complexity of MSZ. It is divided into Eastern and Western Makran due to seismicity and North to South into four parts based on stratigraphy, thrusts and folds. This review aims to give suggestions for the hypothesis on PIMM which was inferred as a separate microplate.


1994 ◽  
Vol 41 (2) ◽  
pp. 176-184 ◽  
Author(s):  
John J. Clague ◽  
Peter T. Bobrowsky

AbstractA peaty marsh soil is sharply overlain by a sand sheet and intertidal mud at tidal marshes near Tofino and Ucluelet, Vancouver Island, British Columbia. Foraminifera and vascular plant fossils show that the buried soil was submerged suddenly and was covered quickly by sand. Radiocarbon ages place this event between 100 and 400 yr ago. The coastal subsidence suggested by the submergence occurred in an area of net late Holocene emergence, perhaps during the most recent great earthquake on the northern part of the Cascadia subduction zone. The sand sheet overlying the peaty soil records the tsunami triggered by this earthquake. Similar stratigraphic sequences of about the same age have been reported from estuaries along the outer coasts of Washington and northern Oregon, suggesting that hundreds of kilometers of the Cascadia subduction zone may have ruptured during one, or a series of plate-boundary earthquakes less than 400 yr ago.


The subduction zone under the east coast of the North Island of New Zealand comprises, from east to west, a frontal wedge, a fore-arc basin, uplifted basement forming the arc and the Central Volcanic Region. Reconstructions of the plate boundary zone for the Cainozoic from seafloor spreading data require the fore-arc basin to have rotated through 60° in the last 20 Ma which is confirmed by palaeomagnetic declination studies. Estimates of shear strain from geodetic data show that the fore-arc basin is rotating today and that it is under extension in the direction normal to the trend of the plate boundary zone. The extension is apparently achieved by normal faulting. Estimates of the amount of sediments accreted to the subduction zone exceed the volume of the frontal wedge: underplating by the excess sediments is suggested to be the cause of late Quaternary uplift of the fore-arc basin. Low-temperature—high-pressure metamorphism may therefore be occurring at depth on the east coast and high-temperature—low-pressure metamorphism is probable in the Central Volcanic Region. The North Island of New Zealand is therefore a likely setting for a paired metamorphic belt in the making.


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