Sendai Plain Research Articles

東北地方太平洋沖地震津波による仙台平野南部での海岸堤防被災・洗掘に関する調査

Field survey on coastal dike damage and scouring induced by the Great East Japan Earthquake Tsunami was conducted in the Southern Part of Sendai Plain. Erosion rate of dike cross section was estimated by using topographical data obtained by airborne laser scanner. The erosion rate tends to increase with relative height of coastal dike from the landside ground. Tsunami overtopping caused scouring at the landward toe of coastal dike, being a trigger of dike failure. Cross-sectional shape of the ground induced by scouring and thickness of tsunami deposit was estimated by portable dynamic cone penetration test and trench survey.

Agent-based Simulation of the 2011 Great East Japan Earthquake/Tsunami Evacuation: An Integrated Model of Tsunami Inundation and Evacuation

The 2011 Great East Japan Earthquake/Tsunami was a magnitude 9.0 Mw event that destroyed most structural tsunami countermeasures. However, approximately 90% of the estimated population at risk from the tsunami survived due to rapid evacuation to higher ground or inland. In this paper, we introduce an evacuation model integrated with a numerical simulation of a tsunami and a casualty estimation evaluation. The model was developed in Netlogo, a multi-agent programming language and modeling environment for simulating complex phenomena. GIS data are used as spatial input information for road and shelter locations. Tsunami departure curves are used as the start time for agents deciding to evacuate in the model. Pedestrians and car drivers decide their own goals and search for a suitable route through algorithms that are also used in the video game and artificial intelligence fields. Bottleneck identification, shelter demand, and casualty estimation are some of the applications of the simulator. A case study of the model is presented for the village of Arahama in the Sendai plain area of Miyagi Prefecture in Japan. A stochastic simulation with 1,000 repetitions of evacuation resulted in a mean of 82.1% (SD=3.0%) of the population evacuated, including a total average of 498 agents evacuating to a multi-story shelter. The results agree with the reported outcome of 90% evacuation and 520 sheltered evacuees in the event. The proposed model shows the capability of exploring individual parameters and outcomes. The model allows observation of the behavior of individuals in the complex process of tsunami evacuation. This tool is important for the future evaluation of evacuation feasibility and shelter demand analysis.

Tohoku Inundation Spurs Hunt for Ancient Tsunamis

Sand layers beneath Japan's Sendai Plain and other regions are evidence of massive tsunamis that struck eons ago and may augur future disaster risk.

New insights of tsunami hazard from the 2011 Tohoku-oki event

We report initial results from our recent field survey documenting the inundation and resultant deposits of the 2011 Tohoku-oki tsunami from Sendai Plain, Japan. The tsunami inundated up to 4.5 km inland but the > 0.5 cm-thick sand deposit extended only 2.8 km (62% of the inundation distance). The deposit however continued as a mud layer to the inundation limit. The mud deposit contained high concentrations of water-leachable chloride and we conclude that geochemical markers and microfossil data may prove to be useful in identifying the maximum inundation limit of paleotsunamis that could extend well beyond any preserved sand layer. Our newly acquired data on the 2011 event suggest that previous estimates of paleotsunamis (e.g. 869 AD Jōgan earthquake and tsunami) in this area have probably been underestimated. If the 2011 and 869 AD events are indeed comparable, the risk from these natural hazards in Japan is much greater than previously recognized.

Tsunami source of the 2011 off the Pacific coast of Tohoku Earthquake

Tsunami waveform inversion for the 11 March, 2011, off the Pacific coast of Tohoku Earthquake (M 9.0) indicates that the source of the largest tsunami was located near the axis of the Japan trench. Ocean-bottom pressure, and GPS wave, gauges recorded two-step tsunami waveforms: a gradual increase of sea level (~2 m) followed by an impulsive tsunami wave (3 to 5 m). The slip distribution estimated from 33 coastal tide gauges, offshore GPS wave gauges and bottom-pressure gauges show that the large slip, more than 40 m, was located along the trench axis. This offshore slip, similar but much larger than the 1896 Sanriku “tsunami earthquake,” is responsible for the recorded large impulsive peak. Large slip on the plate interface at southern Sanriku-oki (~30 m) and Miyagi-oki (~17 m) around the epicenter, a similar location with larger slip than the previously proposed fault model of the 869 Jogan earthquake, is responsible for the initial water-level rise and, presumably, the large tsunami inundation in Sendai plain. The interplate slip is ~10 m in Fukushima-oki, and less than 3 m in the Ibaraki-oki region. The total seismic moment is estimated as 3.8 × 1022 N m (Mw = 9.0).

Impact of Urbanization and Climate Change on Aquifer Thermal Regimes

We evaluated the past impacts of urbanization and climate change on groundwater—in particular, aquifer temperature—in the Sendai plain, Japan, and further compared with the probable changes due to changing climate in the future. A series of simulations were performed and matched with the observed temperature-depth profiles as a preliminary step for parameter calibration. The magnitude of ground surface warming estimated from subsurface temperature spans 0.9–1.3°C, which is consistent with the calibrated ground surface warming rates surrounding various observation wells (0.021–0.015°C/year) during the last 60 years. We estimate that approximately 75% of the ground surface temperature change can be attributed to the effect of past urbanization. For the climate predictions, climate variables produced by the UK Hadley Centre’s Climate Model (HadCM3) under the A2, A1B and B1 scenarios were spatially downscaled by the transfer function method. Downscaled monthly data were used in a water budget analysis to account for the variation in recharge and were further applied in a heat transport equation together with the estimated ground surface warming rates in 2080. Anticipated groundwater recharge under the projected climate in 2080 would decrease by 1–26% compared to the 2007 estimates, despite the projected 7–28% increase in precipitation, due to a higher degree of evapotranspiration resulting from a 2.5–3.9°C increase in surface air temperature. The overall results from the three scenarios predict a 1.8–3.7°C subsurface temperature change by 2080, which is notably greater than the previous effect of urbanization and climate change on aquifer temperature in the Sendai plain.

Survey of 2011 Tohoku earthquake tsunami inundation and run-up

[1] At 14:46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2000 km stretch of the Japanese coast. More than 5300 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. On the Sendai Plain, the maximum inundation height was 19.5 m, and the tsunami bore propagated more than 5 km inland. Along the ria coast from about 50 to 200 km north of Sendai, the narrow bays focused the tsunami waves, generating the largest inundation heights and run-ups. The survey data clearly show a regional dependence of tsunami characteristics.

Climate change impacts on groundwater temperature change in the Sendai plain, Japan

AbstractGroundwater temperature is a key parameter regulating the ecological balance of the ecosystems in groundwater dominated wetlands, estuaries and ponds. This study evaluated the potential impacts of climate change on groundwater temperature and proposed a methodology for use in areas with limited hydrological and metrological data. Groundwater temperatures were measured in 1 m intervals in five observation wells and used for groundwater recharge estimation. Three different techniques, the water balance method, the water level fluctuation (WLF) method and Darcy's method, were performed to verify the estimated recharge rates from the temperature‐depth profiles. Of the six sets of global climate model (GCM) predictions analysed, three of them were selected by considering a range of potential climate changes in the future. The transfer function method was used to downscale the GCM outputs of precipitation and temperature of the Sendai plain. Raw GCM data for nine scenarios (A2, A1B, and B1 from HADCM3, MRI, and ECHAM5 models) and observed data from 1967 to 2006 were used to develop the transfer functions. Derived functions, which were tested for 1927–1966, were used to downscale GCM data for 2060–2099. These predictions were used in a one‐dimensional heat transport model, which was calibrated to the existing site conditions by the water budget technique. There are marked differences among the scenarios and GCMs. However, all the model scenarios projected increasing trends in temperature and precipitation for the 2060–2099 time period. HADCM3 A2 scenario shows the strongest effect compared with the base line climate (1967–2006), which involves an increase in the air temperature of 3·9 °C and an increase in annual precipitation of 345 mm. When considering all GCM scenarios compared with observations in 2006, the aquifer temperature at 8 m depth from the ground surface could possibly increase within the range of 1·2–3·3 °C by 2080. The above findings from the methodology developed here will be important for estimating the impact of climate change and will be useful for environmental management programs. Copyright © 2011 John Wiley & Sons, Ltd.

Spatial distribution of scattering loss and intrinsic absorption of short-periodSwaves in the lithosphere of Japan on the basis of the Multiple Lapse Time Window Analysis of Hi-net data

SUMMARY Propagation of short period S waves through the crust is strongly controlled by scattering loss and intrinsic absorption. Scattering loss controls the shape of the seismic envelope and the spatial distribution of the energy while intrinsic absorption produces an exponential decay as a function of time which is independent of the coordinates. Since both parameters have a different effect, it is possible to compute them by means of the Multiple Lapse Time Window Analysis (MLTWA). In this paper, high resolution maps of Japan for both seismic S-wave attenuation parameters are obtained by using the MLTWA with data provided by the Hi-net seismic network. The maps show strong regional variation of the parameters. The variations depend mainly on the tectonic setting of each region and volcanism mechanisms. In the scattering loss maps, in the 1–2 Hz map, there is a very different behaviour between the northeast (stronger scattering loss) and the southwest (much weaker scattering loss). In the northeast of Japan, areas with strong scattering loss correspond mainly to the location of the volcanic arcs. In Southwest Japan, Chugoku region and the west side of Kii peninsula show strong scattering levels for the 4–8 Hz and higher frequency bands. In Hokkaido, strong scattering loss and intrinsic absorption can be observed for the lower frequency bands. In the Sendai plain, we find strong scattering loss for all the frequency bands. Under all these areas low velocity anomalies have been detected in previous works. In Tohoku area the east side shows lower intrinsic attenuation than the west side. This characteristic seems to extend to the southern part of Hokkaido and to central Japan. In Kanto area, the values of intrinsic absorption are lower than in the surrounding areas; but in the region around the Itoigawa-Shizuoka tectonic line and in its western side strong absorption areas are observed. The behaviour of each area for intrinsic absorption is similar to the behaviour observed in the Q−1c maps. The MLTWA is based on the hypothesis of multiple isotropic scattering in a medium with the homogeneous distribution of scattering mean free path and intrinsic absorption. Although these hypotheses are very simple, the results are very informative on the characteristics of each region, and show the usefulness of studying the properties of scattered seismic waves in the understanding of the properties of the crust.

Tidal effects on aquifer thermal regime: An analytical solution for coastal ecosystem management

An analytical model was developed to estimate the groundwater temperature change in the transition zone (intermediate zone between seawater and fresh groundwater) due to seawater and fresh groundwater temperature change in coastal aquifers . A set of type curves was developed in such a way that the curves account for the advection effect of groundwater flow and can be applied under different aquifer and tidal conditions to estimate the resulting temperature distribution. The proposed method will be important in evaluating the long-term effects of urbanization and climate change on coastal ecosystems where limited observation wells are available. The practical applicability of the composed methodology was tested in the Sendai plain. Continuous 1-h water level (from April, 2005 to July, 2007) and temperature (from May, 2007 to February, 2008) observations were made at three aquifer depths in each observation well at four locations to examine the temporal and spatial variations. Time series analysis was performed to find the correlations of the tidal and groundwater level fluctuations. Results of the preliminary analysis and the time series analysis indicated that the groundwater level within 20 m depth from the ground surface is more sensitive to the recharge from precipitation, while the depths below 20 m are greatly influenced by the tidal fluctuations. Reasonably high cross correlation (0.74) was found in tides with water level fluctuations, and it was also noted that the tidal effect on groundwater level fluctuation and temperature distribution significantly decays as the distance from the coast increases. The simulated temperature distribution from the proposed analytical solution shows good agreement with the observed temperature records. Among the hydrogeologic parameters, hydraulic conductivity has a robust influence in determining the pattern of temperature distribution within the sea water and fresh groundwater boundaries. Verified results in the Sendai plain indicated that the individual effect of seawater temperature change has a more profound effect on temperature change near to the coast than a fresh groundwater temperature change. Combined effects of temperature change at two boundaries within the range of ±1 °C will lead to a 0.4–1 °C temperature change at a distance 500 m away from the coast where in general, the coastal wetlands are located. These figures may be significant for maintaining or achieving the ecological balance of coastal ecosystems, and the findings of this research will assist planners and decision-makers in coastal environment management programs.

Study on the Subsurface Thermal Structure at the Sendai Plain

Study on the Subsurface Thermal Structure at the Sendai Plain

Chronological data for the Middle Miocene to Pliocene sequence around the southwestern Sendai Plain, with special reference to the uplift history of the Ou Backbone Range

Middle Miocene to Pliocene chronostratigraphic data were obtained from three sections on the southwestern margin of the Sendai Plain, northeast Japan. In this tectonically active area, we newly infer the numerical age of the coastal sedimentary sequence on the basis of 27 fission track ages in combination with planktonic foraminiferal and diatom analyses. The Hatatate Formation cropping out along the Natori-gawa Section approximately ranges from 13 Ma to 11.5 Ma in age. The Tsunaki Formation ranges from 10 Ma to 8.3 Ma, and the basal part of the Nashino Formation is assigned to 6.4 Ma. Four major unconformities were recognized in the Middle Miocene to Pliocene sequence in the study area from a compilation of chronological data: ca. 9 Ma, 6.4Ma, latest Miocene, and 3.5Ma, respectively. The oldest unconformity was newly identified in this study. Formative timings of these unconformities correlate well with the uplift history of the Ou Backbone range reconstructed by Nakajima et al. (2006). These data provide a restriction to reconstruct the uplift history of the Northeast Honshu Arc.

地下温度に関する研究の現状と水文学的知見の貢献

Subsurface thermal regime is affected not only by thermal conduction but also by advection owing to groundwater flow. The effect of thermal advection is especially large in shallow sedimentary layer with active groundwater flow. Subsurface temperature distributions in some basins and plains in Japan are affected by regional groundwater flow systems. Both field observation and simulation results in the study area show that thermal transport conducted by regional groundwater flow system, driven by topographic effect, distorts subsurface temperature distributions. Moreover, subsurface temperature distributions in the Yonezawa Basin and Nagaoka Plain show effect of groundwater pumping. Subsurface temperatures in shallow layers in these areas have seasonal change due to groundwater pumping for snow melting in winter season.In recent years, subsurface temperature data have been used for reconstruction of ground surface temperature (GST) history as well. The effects of temperature change at the ground surface in the past have conducted into subsurface and have been recorded as transient temperature perturbations onto the background thermal field. Many studies on GST history in North America and Europe are inferred from inversion of borehole temperature profiles in log data.On the other hand, direct utilization of low-temperature geothermal resources, such as geothermal heat pump system, is important from the viewpoint of reduction of CO2 that causes global warming. Such systems are gradually increasing in Japan. To evaluate the influence of direct utilization onto subsurface temperature, an areal simulation, which numerical model was cut out from regional 3D groundwater flow and heat transport model of the Sendai plains, was conducted.Subsurface temperature observed with comparative ease includes important clues to understand global environment problems and/or hints for development of new energy to preserve global environment.It is hoped that hydrological knowledge contributes to understand many problems in various studies with subsurface temperature.

Effects of hydrogeological and climate change on the subsurface thermal regime in the Sendai Plain

We estimated the effects of hydrogeological and surface temperature warming on subsurface thermal regime from the temperature–depth profiles and hydrological data of groundwater quality both in the quaternary and tertiary systems in the Sendai Plain as a preliminary step toward reconstruction of climate changes. Annual mean air temperature in the plain has increased about 1.5 °C in the last 70 years and this surface warming resulted in low or negative thermal gradient. However, anomaly of thermal gradient was recognized in not all temperature–depth profiles. Groundwater chemical compositions and stable isotope data (δD and δ 18O) show that the groundwater flow system has marked difference between those of tertiary and quaternary systems. Calculated results of three dimensional groundwater flow and heat transport model ensure the above hypothesis and shows that thermal gradient changes at close to basement of the quaternary system. The differences in groundwater flow systems are expressed as subsurface thermal gradient anomalies in the temperature–depth profiles in the Sendai Plain. Furthermore, one-dimensional numerical analyze including the effect of surface warming indicates that calculated profile has departure from steady state line at depths in 60–80 m agree well with observed one.

Thermal effect of the sea breeze on the structure of the boundary layer and the heat budget over land

The daytime boundary-layer heating process and the air-land heat budget were investigated over the coastal sea-breeze region by means of observations over the Sendai plain in Japan during the summer. In this area, the onset of the sea breeze begins at the coast around 0900 LST, intruding about 35 km inland by late afternoon. The cold sea breeze creates a temperature difference of over 10°C between the coastal and inland areas in the afternoon. On the other hand, warm air advection due to the combination of the counter-sea breeze and land-to-sea synoptic wind occurs in the layer above the cold sea breeze in the coastal region. Owing to this local warm air advection, there is no significant difference in the daytime heating rate over the entire atmospheric boundary layer between the coastal and inland areas. The sensible heat flux from the land surface gradually decreases as distance from the coastline increases, being mainly attributed to the cold sea breeze. The daytime mean cold air advection due to the sea breeze is estimated asQ adv local =−29 W m−2 averaged over the sea breeze region (0∼35 km from the coastline). This value is 17% of the surface sensible heat fluxH over the same region. The results of a two-dimensional numerical model show that the value ofQ adv local /H is strongly affected by the upper-level synoptic wind direction. The absolute value ofQ adv local /H becomes smaller when the synoptic wind has the opposite direction of the sea breeze. This condition occurred during the observations used in the present study.

Traces of Tsunami Preserved in Inter-Tidal Lacustrine and Marsh Deposits: Some Examples from Northeast Japan

The Japan Sea Earthquake of May 26, 1983 triggered a large-scale tsunami that surged over the coast of NE Japan and caused considerable damage. The tsunami resulted in peculiar sedimentary processes on the coast. Depending on the hydraulic scale of the tsunami, three kinds of sedimentary processes were recognized, each of which left unique deposits. Such deposits are expected to remain in sedimentary sequences, preserving remarkable sedimentary facies. Borehole samples drilled at different localities in coastal regions have been examined to detect traces of ancient tsunamis. Sedimentological and geochemical studies of the samples reveal that layered deposits, similar to those developed by the Tsunami of the Japan Sea Earthquake, are common in the drilled cores. Estimated ages of these deposits are exactly equivalent to the dates of ancient tsunamis documented in historical records. These results show that the invasion of tsunamis is recorded in coastal depositional sequences. From analyses of long borehole cores we conclude that large-scale tsunamis produced by submarine earthquakes have invaded the coastal regions of the Tsugaru and Sendai Plains at intervals of 250 to 400 yr and about 800 yr, respectively.

仙台平野における貞観11年 (869年) 三陸津波の痕跡高の推定

It is known that great Sanriku tsunamis sometimes hit the Sendai Plain in the north part of the Honshu Island in Japan. Among those great tsunamis, the field investigation had been rarely carried out about the tsunami of July 13th, 869 (11th year of the Jogan Era) because of the lack of the materials of old documents. We carried out the field investigation of the height of this tsunami in the Sendai Plain on the basis of the archaeological view and the sedimentologic examination. The former method is based on the archaeologist's judgement whether historic relics have the trace buried by the running water or not. We estimated the inundated area from the result of the survey for the 8 points in the Sendai Plain. In the latter method, we dipped the test pit and observed the soil layer of the side wall minutely to find the sand layer being supposed to be carried by the tsunami from the dune. Moreover to analyze the character of the sand layer, we made the physical examination, the chemical analysis and the measurement of the age by 14C method. From the results of these investigations, the height of the Sanriku Jogan 11 earthquake-tsunami (A. D. 869) is estimated as 2.5-3m at the point 3km from the coastline in the Sendai Plain. Finally we checked it with the social and geographic circumstances at that time, and we got the result that the estimated height is not inconsistent with the record of this tsunami.

テフロクロノロジーによる前期旧石器時代遺物包含層の検討 仙台平野北部の遺跡を中心に

A very important problem for Quaternary research is determining when human beings first settled the Japanese islands. Recently many artifacts of the Early Paleolithic age, dating from before 30, 000 years ago, have been discovered in the northern part of Sendai plain, North Japan. The age of these artifacts has been determined mainly by radiometric dating methods.On the other hand, tephrochronology is an effective technique for establishing Quaternary stratigraphy in the Japanese islands and their surrounding area. The author investigated the age of horizons bearing artifacts on representative sites of that age from the viewpoint of tephrochronology.The stratigraphy of proximal tephra layers is indicated in Fig. 1. Useful widespread tephra layers for chronological study of this area are Toya (ca. 90, 000-100, 000y.B.P.), On-Pm I (ca. 80, 000y.B.P.), Aso-4 (ca. 70, 000y.B.P.) and AT (ca. 21, 000-22, 000y.B.P.). Toya, On-Pm I, Aso-4 and AT were discovered from the horizons between IcP and KtA, IcP and KtA, N-N and N-Y, and N-Y and NK-U, respectively. At Babadan A site, artifacts of the Early Paleolithic age were excavated from horizons in Ando soil found below IwP, just below and above IcP, between IcP and KtA, just above N-Y, and between N-Y and NK-U. Consequently, the artifacts excavated from the horizons below KtA belong to the Early Paleolithic age. At Zazaragi site, another representative site belonging to the Early Paleolithic age, the artifacts were excavated from the horizons of orange-colored volcanic ash (the lower part of Yasuzawa volcanic ash). During the excavation, this deposit was regarded as an airfall tephra layer. But the author interpreted this deposit as a weathered part of a pyroclastic flow deposit (N-Y3) on the basis of the following observations:(1) The boundary of the lower part of Yasuzawa volcanic ash and lower pyroclastic flow deposit is irregular and not clear in some place.(2) It is massive and not layered. There is no intercalation of soil.(3) It is not well sorted.(4) It includes charcoals.(5) It has segregation pipes. Some of them develop at the boundary of the lower part between the Yasuzawa volcanic ash and the lower pyroclastic flow deposit.The author believes that the artifacts were incorporated into pyroclastic flow and carried to their present site.The horizons from which artifacts of the Early Paleolithic age in Japan have been excavated are plotted in Fig. 8. It has been confirmed that some widespread tephra layers originated from gigantic eruptions and covered the area surrounding the Sea of Japan (cf. MACHIDA and ARAI, 1933). The author believes that common chronological studies of Paleolithics in this area are made feasible by tephrochronology.

Occurrence of Snow Rot of Barley and Wheat, Caused by Typhula ishikariensis S. Imai, in the Sendai Plain

Occurrence of Snow Rot of Barley and Wheat, Caused by <I>Typhula ishikariensis</I> S. Imai, in the Sendai Plain

Regionality of Farmhouse Building Constitution and its Genesis in Tohoku

Although some dynamic aspects in Japanese farmhouse building constitition have been studied in disciplines of settlement geography and architecture, the regional understanding of such aspects is not sufficient yet from the viewpoint of comparalive geography. This paper is an inquiry into genetical processes of regional types of farmhouse building constitution in Tohoku, northeastern Japan. The author examinedthe present aspects and the changing processes of farmhouse building constitution in some investigation villages selected from two major regions, the central part of Iwate Prefecture and the Aizu District, and further compared them to those in the Sendai Plain discussed formerly.Each region has a characteristic pattern in building constitution. In the Sendai Plain farmhouses have usually many attached buildings, to whih various functions are distributed. On the contrary, in Aizu District they have relatively few attached buildings and farm functions are concentrated in Sagyosha (workshop or barn), the main attached building. Central Iwate is intermediate between above two regions concerning the number of attached buildings and the space of Sagyosha floor. The present author identified from these patterns three regional types of building constitution in Tohoku; multi-building type in Sendai Plain, mono-building type in Aizu and intermediate type in central Iwate.Each of these regional types has appeared in the process separation of attached buildings at two stages. The first stage occured before World War II. Multibuilding type in Sendai Plain is considered to have been established by the Taisho Period (1912-1925). In the central Iwate and Aizu, a considerable number of Sagyoshas were built at first from the 1910's to the 1930's. Through these decades the building constitution began to be differenciated from region to region. The second stage occured after World war II. Since 1955 a great number of Sagyoshas and other attached buildings have been added anywhere in Tohoku. Through this period the present charcters of each regional type were established.These two stages were respectively under different socio-economic conditions. The separation of Sagyosha in the first stage was caused by the spread of treadle and power thrashers. The construction of various attached buildings in the second stage was a resullt of the recent large scale mechanization in agriculture. The main house itself changed from dirt floor to plate floor in domaniwa hall in the first stage and in the second stage it was wholly rebuilt in large scale. As a result of the rebuilding, the peculiar traditional house types such as Nanbumagariya and Chumonzukuri were almost lost in the investigation villages. The above changes proceeded in the first stage mainly among comparative by upper class farmers, but in the second stage they spread into lower classes.Differences in those regional types are considered to have been brought about primarily by climatic conditions. Namely, in Aizu under snowy winter climate various functions are agglomerated in a few buildings for daily convenience and house-building difficulties. It might he necessary to further consider the relationships to agricultural structure and folk practice etc.