Contents of Active Fault Map

Active faults are divided into four categories according to their shape and certainty of location: 1) active fault, 2) active fault (site indistinct), 3) active flexure, and 4) active fault (concealed).
In addition, faults which are currently difficult to ascertain as active are listed as "presumed active fault," while presumed active faults that are covered by a new layer(s) and cannot be identified as faults from the surface but show evidence of being active faults from previous boring, physical surveys, etc., are listed as "presumed active fault (by prospecting data)."
Active Fault Trace symbol of active fault trace Faults that during the past hundreds of thousands of years, have seen repeated activity in intervals of roughly 1000 to tens of thousands of years that have left their mark on the landform and which may continue to repeat seismic activity in the future. There is clear topographic evidence to delineate their location.
Active Fault Trace (site indistinct) symbol of active fault trace (site indistinct) Faults whose precise location cannot be delineated because erosion, human activity, etc., has erased their traces.
Active Flexure symbol of active flexure These are active faults that are diffused in soft layers and appear on the surface not as unevenness but as flexures. This symbol shows the range and the dip direction of flexures.
Active Fault Trace (concealed) symbol of active fault (conceald) These are active faults that have been covered by layers since their last period of activity and thus there is no topography that directly indicates displacement.
Strike Slip symbol of strike slip Arrows show the relatively horizontal direction of displacement of active faults.
Dip Slip symbol of dip slip Short lines indicate the side that is relatively falling and direction of vertical displacement of active faults.
Earthquake Fault symbol of earthquake fault A fault which clearly shows displacement due to a seismic event. (Without a displacement that is obviously caused by landslide, land subsidence, liquefaction and so on.)
Trench Survey Site symbol of trench survey site A point along a fault line where a survey ditch ("trench") is dug to take interpretive surveys of fault movements (many different types of survey research organizations have taken surveys at these points).
Name of Active Fault name of active fault[Japanese] Proper name of fault
Presumed Active Fault symbol of presumed active fault Topographical characteristics can be used to estimate the locations of existing faults, but the precise location cannot be determined. It is also uncertain whether there will be repeated activity in the future.
Presumed Active Fault (by prospecting data) symbol of presumed active fault (by prospecting data) Although there is a new soil cover and the surface cannot be confirmed to exhibit fault topography, boring tests and geophysical surveys indicate the existence of an active fault.
Active Fold symbol of active fold Wave-like topography resulting from the continuing tectonic activity. This topography is shown with continuing lines of concave or convex.
Tilting Surface Direction symbol of tilting surface direction This is a place where the surface is inclining due to continuing tectonic activity. An arrow indicates most heavily inclined direction.
Higher Terrace symbol of higher terrace This is a flat surface formed by the action of rivers or the sea that became land area hundreds of thousands of years ago.
Middle Terrace symbol of middle terrace This is a flat surface formed by the action of rivers or the sea that became land area tens of thousands of years ago.
Lower Terrace symbol of lower terrace surface This is a flat surface formed by the action of rivers or the sea that became land area tens of thousands, or even several thousand, years ago.
Alluvial Lowland symbol of alluvial lowland This is a flat land surface formed by the action of rivers or the sea several thousand years ago into the historic period. There is a possibility that undiscovered faults exist beneath the ground.
Alluvial Fan symbol of alluvial fan This is a semi-circular landform having an apex at the mouth of a valley and spread out in a fan shape toward a lowland. There is a possibility that undiscovered faults exist beneath the ground.
Filled-up Land/Reclaimed Land symbol of filled-up land/reclaimed land These are new land areas formed by filling in or drain wetlands or tidal flats. The map shows such lands that have been developed in Japan, especially since the 1860s. There is a possibility that undiscovered faults exist beneath the ground.
Landslide symbol of landslide An area where part of the rock, soil, etc., constituting a slope is slipping down the slope. It is an indication of the range of landslide scrap and slipping soil clumps.
Offset Channel symbol of offset channel Offset channel by strike slip fault
Crater/Caldera symbol ofCrater/Caldera These are roughly circular enclosed depression of volcanoes. It is an indication of the outer edge.
Surface of Pyroclastic Flow Deposit symbol of surface of pyroclastic flow deposit This is a flat land formed at the time of the eruption by deposition of a mixture of volcanic ash, pumice, lava fragment, and volcanic gas that flow down the slope of a volcano.
Surface of Mudflow Deposit symbol of surface of mudflow deposit This is a flat land formed by the deposition of downward-flowing fluids (mud flows) containing fine-grained mud particles.
Surface of Debris Avalanche Deposit symbol of surface of debris avalanche deposit This is undulating topography that is created by the deposition of downward-flowing rocks of various size caused by sector collapse, etc.
Active Fault Trace(Sea Bottom) symbol of active fault (sea bottom) Sonic wave probes on the sea floor have indicated the presence of potentially active faults on the sea bottom .
Presumed Active Fault (Sea Bottom) symbol of presumed active fault (sea bottom) This is a fault-like structure on the sea floor that cannot be clearly identified as active faults at the present time.