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震波频谱图，又名“震波凸形图（ｓｅｉｓｍｉｃ ｔｏｐｏｇｒａｐｈｙ）”是Ｓ．Ｊ．Ｄｕｄａ关于谱震级概念的发展。对应于宽频带地震图相应于每一道带通频率ｆｍ来折算的瞬时振幅所组成的面（为二维包络面），沿着时间轴作出剖面，例如０．３赫芝的带中频率相匹配的带通滤波器所输出的包络线。而三维可视化技术则允许快速估算其相应振幅的分布，要能判明其高峰位置的相应分布，则不太容易，因此我们就将其剖面投影在二维的分布图上。为了辨识震波强度的分布，将此图配上相应的颜色，及其前置的颜色标尺，与其振幅值相对应。图中的等值线有助于识别图中的峰和谷并与高或低强度相对应。这种对宽频记录时间一频率分布的表达方式，用颜色和等值线来表示振幅值，我们称它为“频谱震波图”。可转化为三维图形，其中每一条线代表由相应带中频率ｆｍ计算得的包络线，用灰度表示等值线，估算震波强度或振幅的二维分布，又称为“震波凸形图”，它反映了在地震台记录的信号能量随频率和时间的分布，从而看出其最大强度所对应的频率范围。震波频谱图允许对随时间而变化的频谱分量在时间和强度的定位方面有较好的分辨率。在中国及邻近地区已试用该方法，说明有助于识别地震系列的特征。
Shock spectrum, also known as “seismic topography” is S. J. Duda’s development of the concept of spectral magnitude. The plane (which is a two-dimensional envelope) corresponding to the instantaneous amplitude of the broadband seismograms corresponding to the band-pass frequency fm of each channel is profiled along the time axis, for example a mid-frequency phase of 0.3 Hertz The envelope of the matched bandpass filter. However, the three-dimensional visualization technology allows the rapid estimation of the corresponding amplitude distribution. It is not easy to find out the corresponding distribution of the peak positions. Therefore, we project the profile on a two-dimensional distribution graph. In order to identify the distribution of the intensity of the shock wave, the figure is assigned a corresponding color, with the color scale preceding it, corresponding to its amplitude value. Contours in the figure help to identify peaks and valleys in the graph and correspond to high or low intensities. This expression of a frequency distribution of broadband recording time, using color and contour to represent the amplitude value, we call it “spectral vibration wave.” Which can be transformed into three-dimensional graphics, where each line represents the envelope calculated by the frequency fm in the corresponding band, and the gray level is used to represent the contour to estimate the two-dimensional distribution of the intensity or amplitude of the shock, also known as “ ”It reflects the distribution of the signal energy recorded at the seismograph with frequency and time so as to see the frequency range corresponding to its maximum intensity. Seismic spectrograms allow better resolution of time-versus-intensity positioning of spectral components that vary over time. This method has been tested in China and adjacent areas to illustrate features that can help identify seismic series.