Dynamics of the Zones of Strong Earthquake Epicenters in the Arctic–Asian Seismic Belt

Round 1

Reviewer 1 Report

This paper aims to provide a comprehensive clarification on tectonic features related to seismotectonic activity along the plate boundaries of Eurasia, North America and Okhotsk Plate in eastern NE Asia. The strength of the paper is a comprehensive overview of information from a key, but very remote area. Data from this area are really needed but they were so far sparse and mostly dispersed in local Russian journals.

The manuscript has also some weaknesses:

Overloading with local names and details of regional geology - an effort to simplify a regional context is highly recommended.

Methodological chapter is a bit wired. It contains a very general description of an approach that is rather a work flow than method. Furthermore, there are only limited references to the approach initially described throughout the further text of the manuscript. Please, consider simplification of this chapter, providing information what you have actually used: focal mechanisms, remote sensing data, field observations of deformation.

English requires some linguistic editing.

I made several corrections directly on an annotated manuscript that is attached to my review.

I hope my review will help to improve your work.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

We are grateful for the comments and recommendations concerning our manuscript.

Below, there is a list of changes made according to them.

The corrected lines are numbered according to the numbering of the lines in the PDF file where your comments were given.  

Sincerely yours, Lyudmila Imaeva

Comments

1. The territory of the Arctic-Asian belt is located in the Republic of Sakha (Yakutia). The toponymy of local names is really complicated. However, all Russian and foreign researchers of this territory use these local names. According to your recommendation, we have reduced the list of the local names used in both the text and drawings of our paper.

2. In addition to the new method developed by the authors (concerning the geodynamic activity of the recent/modern structures) [1, 3], the Methods chapter describes the sequence of our seismotectonic studies. It is this workflow that allows obtaining reliable results. The main goal of our paper is to define the blocks accumulating tectonic stresses that can produce M ≥ 6.0 earthquakes. We consolidated the database using our 40+-years experience of detailed research of the Arctic-Asian seismic belt. We used a whole range of laboratory and field studies in areas of the strong earthquakes. Therefore, the sequence of research works outlined in the Methods chapter is of great importance. Our data are included in the Russian regulatory maps of seismic zoning. Unfortunately, in the last 20 years, the territory of the Arctic- Asian seismic belt was practically not investigated due to a lack of possibility to access it. Our most recent publications included in the list of references provide the new data on the study area.

In the list of references, we have included the latest publications on seismotectonics of the Arctic- Asian seismic belt. The most recent publication: Imaeva L.P, Imaev V.S. and Koz’min B.M. Seismotectonic Activation of Modern Structures of the Siberian Craton // Geotectonics, 2018. V. 52. No. 6. Pp. 618–633. DOI: 10.1134/S0016852118060031

Corrections in the text

Page 1

Line 9. destruction was replaced by deformation

Line 14. degrees was removed

Line 17. structural tectonic was removed

Line 18. A set of models has been constructed for the studied segments with account of the dynamics of the regional geological structures was replaced by A set of models has been constructed for the studied segments of plate boundaries with account of the dynamics of the regional geological structures.

Page 2

Line 55. structural tectonic was removed

Line 60. authored was replaced by elaborated

Line 62. Arctic and hereinafter in the text we used it in singular

Line 62. stage was replaced by one

Line 63. Late  Here and hereinafter in the text we used the spelling of the names of geological times with a capital letter in accordance with the International Chronostratigraphic Chart (see for example International Commission on Stratigraphy http://www.stratigraphy.org/index.php/ics-chart-timescale).

Page 3

Line 64. that the recent tectonics is was replaced by the recent tectonics as

Line 66. degrees was replaced by degree

Line 76. material and was replaced by material composition

Line 83. activation was replaced by activity

Line 101. the  was removed

Line 105. parageneses  we prefer use our variant

Line 110. the was replaced by some

Page 4

Line 123. the was replaced by a

Line 123. marginal structures was replaced by structures

Line 146. folding was replaced by folding was

Line 148. the was removed

Lines 150–151. non-conformably overlaid was replaced by un-comformably overlain

Line 152. the was replaced by that

Line 153. Miocene basis of the marine geophysical survey data was replaced by Miocene

Line 154. Bel’kovsky Svyatoy was replaced by Bel’kovsky–Svyatoy

Line 180. the was removed

Page 7

Line 234.  wherein was replaced by where

Line 240. tectonic was removed

Line 250. at was replaced by on

Line 250. dislocated was replaced by deformed

Line 252. Paleogenic was replaced by Paleogene

Line 253. in the zone of was replaced by along

Page 8

Line 267. tectonic was removed

Page 9

Lines 284–285. available geological and geophysical datasets was not changed

Line 296. ditches was replaced by grabens

Line 297. confined was replaced by related

Page 10

Line 320. by outcropped activated was replaced by by the outcropped

Lines 324–326. The normal faults are detected in the western side of the Buor–Khaya Bay. They cut the basement of the rift structure, and many of them penetrate into the upper horizons of the sedimentary cover, which suggests their young age (Pliocene Quaternary). was replaced by

The faults cut the basement of the rift structure, and many of them penetrate into the upper horizons of the sedimentary cover, which suggests their young age (Pliocene-Quaternary).

Page 11

Line 328. to the surface of the was replaced by to the

Line 329. bottom we prefer use this word

Line 330. relation was replaced by relationship

Line 331. area was replaced by areas

Line 334. fields was replaced by regimes

Line 336. region wherein was replaced by region where

Lines 337–340. Similar regions on the globe are the Afar Rift in East Africa (its structures are linked to the mid-ocean ridge in the Indian Ocean), and the Northern California region. In the latter, the northern termination of the East Pacific Upland is linked via the San Andreas Fault with the system of mid-oceanic ridges (Gorda, Juan de Fuca, and Explorer). was replaced by

Similar regions on the globe are the Afar Rift in East Africa, and the Northern California region.

Line 343. fault was replaced by displacements

Line 348. range was replaced by Range

Line 350. tectonic was removed

Line 350. structure was removed

Line 351. the ramp was replaced by ramp

Line 355. belongs was replaced by belongs to

Line 361. overlaid was replaced by overlain

Line 361. of Okhotsk–Chukotka belt was replaced by of the Okhotsk–Chukotka belt

Line 363. by high degrees was replaced by by a high degree

Line 364. parageneses we put this word rather than array

Line 365. structures of geophysical fields was replaced by anomalies of potential fields

Line 367. Geostructural was replaced by Structural

Line 370. geostructural was replaced by structural

Lines 370–372. observations of shifted geological bodies in the fault zones, field and laboratory studies of tectonic fracturing, intensive dislocations of the Cenozoic sediments, as well as cartographic material [26]. was replaced by observations of movements in the fault zones, field studies of tectonic fracturing, intense dislocations of Cenozoic sediments, as well as geological maps [26].

Line 373. of the active was replaced by of active

Page 12

Line 388. features describing was replaced by characteristic of

Line 389. the major was replaced by major

Page 13

Line 392. planes was replaced by faults

Page 14

Line 418. in the was replaced by at the

Lines 421–422. it is higher than the was replaced by it is elevated relative to the

Line 422. In the modern concepts of tectonics, the Omulevsky block was replaced by

The Omulevsky block

Line 423. inside the Mesozoic was replaced by in the Mesozoic

Line 423. structural frame  we decided to put this words

Lines 424–425. Mesozoides (belt folded during the Mesozoic) was replaced by belt

Line 429. planes was replaced by segments

Page 15

Line 440. in the NE article is needed here

Lines 442–444. The distribution of the aftershocks with depth shows that the shear plane of the Chai–Yurya fault is almost vertical. Shearing is also confirmed by the focal mechanism solution of the Artyk earthquake (Figure 9) was replaced by

The distribution of the aftershocks with depth and focal solution of the main shock show strike-slip movements on the nearly vertical fault plane (Figure 9) [2].

Line 446. and overthrust was replaced by and reverse

Lines 448–449. in the zone of influence of the Polousnensky faults and overthrusting in the zone of the earthquake epicenter. was replaced by in the zone of the Polousnensky faults.

Page 16

Line 454. wherein was replaced by where

Lines 454 and 455. thrusted was not changed

Line 456. and overthrust was removed

Line 457. Chersky ridge was replaced by Chersky Ridge.

Line 458. Moma ridge was replaced by Moma Ridge.

Line 459. In the NW was replaced by At the NW

Line 463. compression was replaced by compressional

Lines 474–475. involved in intensive uplifting was replaced by experiencing intense uplift

Line 476. overthrust and was removed

Line 477. in was replaced by from

Lines 479–480. the plane of was removed

Line 481. both a series we removed a

Page 17

Line 490. amplitudes was replaced by displacements

Line 494. magnetic field anomalies and a sharp gradient jump was replaced by magnetic anomalies and a sharp gravity gradient jump

Line 495. intermountain this version is also accepted

Lines 496–497. from the following: the straight line of its route was replaced by by its straightness

Line 502. deformational was replaced by deformation

Line 504. determined was replaced by characterized

Lines 505–506. the ground surface and develop east eastwards at depth as low-angle detachments. was replaced by the surface and continue eastwards as low-angle detachments at depth.

Line 506. thrusted was replaced by thrust

Line 508. overlaid was replaced by overlain

Line 510. data on was replaced by data for

Line 513. and tectonic was removed

Line 515. zone where was replaced by zone, where

Line 517. The compressional forces are subhorizontal was replaced by The principal compressional axis is subhorizontal

Line 520. relative to the ground surface was removed

Line 520. orientations was replaced by orientation

Page 18

Lines 541–542. This model shows transpression (i.e. compression with slip) and the dynamic setting initiated by the interacting frontal structures in the contact zone where the Eurasian was replaced by This model shows transpression setting initiated by the interacting frontal structures in the contact zone between the Eurasian

Line 543. plates move was replaced by plates moving

Line 544. Such setting was replaced by Such a setting

Page 19

Lines 549–550. and structure was removed

Line 566. 4. Discussion was replaced by 4. Discussion and Conclusions

Line 570. dynamics of was removed

Line 577. the setting of was removed

Lines 581–582. in the dynamic types of the was replaced by in the

Line 583. Segment where was replaced by Segment, where

Line 583. mid-oceanic we put this word

Line 584. area in we put the comma

Line 586. the setting of steady was replaced by the steady

Line 591. can therefore be was replaced by can, therefore, be

Page 20

Line 596. wherein was replaced by where

Line 597. mid-oceanic we prefer this word

Line 600. compression we think it should be left

Line 603. distinguished was replaced by characterized

Line 608. in was replaced by at

Author Response File: Author Response.doc

Reviewer 2 Report

Dear authors,

thank you for making your valuable data and ideas available to a broader audience. The region you studied is of global importance, but still lacks regional and local studies due to the remoteness and accessibility of the region.

In general I would suggest to give the manuscript a better structure. So far, it is not clear to me, what are previously published data and results and what are the new ideas. It is also not clear, if the manuscript should be a review of previous works or an original article presenting new data. Also you should explain your methodology in more details. Many of the references are not easy to access or in Russian. Your manuscript would have a much higher impact if you could rate the uncertainties of existing data and interpretations and give some outlook, what kind of studies would be necessary to reduce these uncertainties. This is especially important for areas where you observe quite different focal/fault kinematics.

The figures have in general a high quality, but some figures are a little bit messy (too much information or information is not easy to identify. Maybe the quality of data (e.g., focal mechanism) could be also rated in figures (beside in the text).

Also it is not yet clear to me, how you identified the ages of reactivation of faults, especially the thrust zones. Is there always clear evidence for the (late) Cenozoic reactivation?

Sometimes, I would like to see more references (indicated in the annotated manuscript). Are there also some more recent publications or studies about sealevel changes/ uplift of coastal areas? Could that be an effect of post-glacial rebound?

Throughout the text there are many sentences that repeat something or even say nothing new.

More specific comments you will find in the annotated manuscript.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

We are grateful for the comments and recommendations concerning our manuscript.

Below, there is a list of changes made according to them.

The corrected lines are numbered according to the numbering of the lines in the PDF file where your comments were given.

Sincerely yours, Lyudmila Imaeva

Comments

1. The most reliable methods for determining the age of activity of faults (with various kinematics) are palaeoseismological studies of the fault zones (trenching) and structural-geological analysis. The results of these studies are presented in our paper, as well as in the publications included in the list of references. Imaeva L.P., Imaev V.S. and Koz'min B.M. Seismotectonic Activation of Modern Structures of the Siberian Craton // Geotectonics, 2018. V. 52. No. 6. Pp. 618–633. DOI: 10.1134/S0016852118060031 – this is the latest overview of the genesis of seismotectonic activation at the Siberian Craton and its mountain-fold and coastal-shelf frame structures; it considers fluid-geodynamic and glacial-isostatic factors of activity, as well as the velocities of the recent and modern vertical tectonic movements.

2. In the list of references, we have included the latest publications on seismotectonics of the Arctic- Asian seismic belt. The most recent publication on the sea-level changes in the coastal areas is:

Fedorov G.B., Antonov O.M., Bolshiyanov D.Yu. Features of the regime of modern tectonic movements of Central Taimyr // News of the Russian Geographical Society, 2001. V. 133. Issue 1. P. 76–81.

Bolshiyanov D.Yu., Makarov A.S., Schnaider V., Shtof G. The Origin and Development of the Lena River Delta. AANII, St. Petersburg, 2013. 268 p.

Imaeva L.P, Imaev V.S. and Koz’min B.M. Seismotectonic Activation of Modern Structures of the Siberian Craton // Geotectonics, 2018. V. 52. No. 6.Pp. 618–633.DOI: 10.1134/S0016852118060031

Corrections in the text

Page 1

The structure of the paper was changed, and now it is the following:

1. Introduction

2. Materials and Methods

3. Results

4. Discussion and Conclusions

Page 1

Line 8. studies was replaced by study

Line 9. destruction was replaced by deformation

Lines 14–15. The investigated neotectonic structures are ranked with respect to the regional classification principles constrained on the basis of the degrees of activity of geodynamic processes, and the corresponding classes of neotectonic structures are defined. was replaced by The investigated neotectonic structures are ranked with respect to the regional classification principles.

Line 20. seismogenerating and potentially active structures in the Russian Arctic was replaced by seismogenerating structures in the Russian Arctic

Lines 30–33. We checked it.

Page 2

Figure 1. Location and designation of the lithospheric plate was indicated on the map. OK – Okhotsk

Figure 1. а, б, в were replaced by a, b, c

Figure 1. Balagan-Tas volcano (4) was designated at the map near the indication of the segment IV.

Line 35. Geodynamically active zones are lengthy crustal areas that can concentrate tectonic stresses generated by the internal forces of the Earth and caused by their activity at the present stage of neotectonic development. These zones are characterized by reduced strength, increased fracturing, high permeability, and, as a result, faulting, seismicity, ascending fluid flows and other processes. In our case, geodynamically active zones are seismogenerating structures of the Arctic-Asian seismic belt.

Line 42. It was checked.

Line 44. presents the research results was replaced by reviews published results

Lines 51–53. The research algorithm provides for discovering the tectonic positions and the structural dynamic pattern of the main fields of earthquake epicenters in the study area and allows identifying the blocks that acts as tectonic stress concentrators. was replaced by Our research data provides for discovering the tectonic positions and the structural dynamic pattern of the main fields of earthquake epicentersin the study area and allows identifying the blocks that acts as tectonic stress concentrators.

Page 3

Lines 64–65. that the recent tectonics is a structural framework comprising active faults and other features of modern tectonic activity which are related to regional seismicity. was replaced by the recent tectonics as a structural framework comprising active faults and other features of modern tectonic activity which are related to regional seismicity.

Lines 66–67. and trends of geodynamic processes was removed

Lines 68–70. In our study, a domain is a neotectonic geodynamic taxon of the territorial rank, which is considered an integral object with a specific location. Its main components show the multi-factor interaction features in the geological and geophysical profiles of the crust. was replaced by In our study, a domain is a neotectonic geodynamic taxon of the territorial rank, which is considered as a spatially localized integral object with a multifactorial interaction of its main components in the profile of the earth's crust.

Lines 73–82. The classification of recent tectonic structures by the degree of geodynamic activity is described in the Methods section of our paper and shown in Figure 1. Presenting this classification in the format of a table is not possible due to the diversity of the recent tectonic structures and variations of their level, class, rank, size, and the scale of research. A more detailed description of this classification by the degree of geodynamic activity is published in our papers included in the list of references [1, 3 6, 29].

Line 95. preliminary mapping of active faults was replaced by mapping active faults

Lines 97–105.  We prefer use our variant

Page 4

Line 124. references [8–9] were added.

Page 5

Lines 139–140. We corrected this in the revised version.

Line 149. Anjou was replaced by Anzhu

Lines 151–155. It can thus be suggested that the Cenozoic extension was interrupted by a compression episode at the end of the Miocene basis of the marine geophysical survey data [11, 14–16]. A system of narrow NW-striking grabens and troughs (Ust–Lena, Ust–Yana, Chondon, Bel’kovsky–Svyatoy Nos, etc.), and associated submarine rises is identified in this area (see Figure 2). was replaced by It can thus be suggested that Cenozoic extension was interrupted by a compression episode at the end of the Miocene. According to the seismic profiling, a system of narrow NW-striking grabens and troughs (Ust–Lena, Ust–Yana, Chondon, Bel’kovsky–Svyatoy Nos, etc.), and associated submarine horsts is identified in this area (see Figure 2) [11, 14–16].

Lines 171–175. We corrected this in the revised version.

Line 176. references [1, 7] were added.

Lines 185–186 We corrected this in the revised version.

Page 6

Line 190. Here we refer to Figure 3.

Line 191. northen graben We removed it from the sentence.

Line 192. references [1, 3, 7] were added.

Line 192. seismic was replaced by seismological

Line 193. Compression. It was deduced from focal mechanisms.

Line 194. In this area, overthrusting is caused by the local earthquakes recorded in the zones of contact between the continental and rift structures. was replaced by In this area, thrusting caused local earthquakes in the contact zones between the continental and rift structures.

Line 198. trending folds Yes, folds, not faults.

Line 202. In this zone  This zone is shown at Fig.3

Figure 3. marginal was replaced by regional

Line 206. marginal was replaced by regional

Line 215. When determining focal mechanisms, the regional stations were used.

Page 7

Line 223. A reference to Figure 2 and the references [3, 7] were added.

Line 223. We used published focal mechanisms which are suggested to be well constrained due to regional seismic network. You can see the following works on that (Seredkina A.I., Melnikova V.I. New data on earthquake focal mechanisms in the Laptev Sea region of the Arctic-Asian seismic belt // J. Seismology, 2018.  https://doi.org/10.1007/s10950-018-9762-9)

Line 225. of 15 km This depth value was estimated. This earthquake was studied thoroughly.

Line 227. seismic-data based was removed

Lines 230–231. World Ocean level was replaced by global ocean level.

Lines 234–235. It was corrected.

Lines 243–244. In the Riphean was replaced by In Neo-Proterozoic

Lines 249–250. It was corrected.

Line 252. Paleogenic was replaced by Paleogene. No, it was Paleogene, not Upper Cretaceous.

Page 8

Line 260. 3 – seismic features was replaced by 3 – locations of seismogravity effects

Lines 267–268. There is a reference [21] where details are given.

Line 271. Reference to Figure 4 was added.

Page 9

Line 272. near-shelf was replaced by near-coastal

Line 274. It was corrected. References were added.

Lines 276–280. The last sentence was removed according to your comment.

Lines 282–289. We left it in this Section.

Lines 290–291. We put designations into the text.

Lines 294–295. There are references.

Line 296. in the Cenozoic was replaced by in the Quaternary

Lines 300–301 Their epicenters were located in a crustal block that is clearly detectable from the morphological features. was replaced by  zone in the same crustal block .

Line 302. mobile was replaced by active

Line 303. Kharaulakh Ridg at Fig.4 is confined to the zone of fault numbered III.

Page 10

Figure 5. We added amplitude of displacements in the revised text.

Lines 318–320. Modern activation features are clearly observed in the ‘diagonal link’ zone: it includes more than 20 paleo- and modern seismodislocations caused by gravity and tectonic events. Some of the seismodislocations are marked by outcropped activated fault segments (Figure 5). was replaced by Recent activation features are clearly observed in the ‘diagonal link’ zone: it includes more than 20 paleo- and modern seismodislocations caused by gravity and tectonic events. Some of the seismodislocations are marked by the outcropped fault segments with the horizontal displacement of 5-7  m (Figure 5).

Line 321. Buor–Khaya normal fault zone. Yes. It is one zone.

Lines 324–325. This sentence was removed

Line 325. Age of the sedimentary cover is defined from Quaternary (upper part) to Cretaceous (lower part). References [7, 21] were added.

Line 327. [23] was removed

Page 11

Lines 328–329. references [11, 12] were added.   

Lines 335–342. Here, the text was changed in more logical way.

Line 346. dome structures was replaced by tectonic structures

Line 347. Tuora-Sis Upland was replaced by Tuora-Sis Range. Reference to Figure 4 was added.

Line 348. (Chekanov range) was replaced by (Chekanov Range)

Lines 348–352.  The more detailed consideration of the Kharaulakh Segment can be found in [21].

Lines 369–372. This conclusion is supported by the geostructural observations of shifted geological bodies in the fault zones, field and laboratory studies of tectonic fracturing, intensive dislocations of the Cenozoic sediments, as well as cartographic material [26]. was replaced by This conclusion is supported by the structural observations of movements in the fault zones, field studies of tectonic fracturing, intense dislocations of Cenozoic sediments, as well as geological maps [26].

Page 12

Figure 6. This Figure was simplified. We added a new Figure (Fig.12) where structures and faults were shown more clearly.

Line 379. 7 – isolines of maximum values of seismic activity (A10) was removed

Lines 380, 381. marginal was replaced by regional

Line 382. Ulahan was replaced by Ulakhan

Line 387.  Yes, the Ulakhan fault is shown at the map under number 14.

Line 388. It has a complete set of features describing similar fault systems located in other regions of the world: was replaced by It has a complete set of characteristic of similar fault systems located in other regions of the world:                        

Lines 389–391.  We added a reference [24].

Page 13

Figure 7 was changed.

Figure 7 Location of the May 18, 1971 M6.6 Artyk earthquake epicenter was shown more correct at the modified Fig.7

Line 406. reference [28] was added.

Page 14

Figure 8. Location of Fig.8 is shown at Figs.6 and 7.

Line 418. reflect was replaced by  reflects

Line 419. Both faults are clearly detectable on medium- and large-scale satellite images. was replaced by Both faults are clearly detectable on satellite images.

Line 421. the was removed

Line 422–426. In the modern concepts of tectonics, the Omulevsky block is viewed as a terrane that formed inside the Mesozoic structural frame during collisional and post- collisional transformations of the Verkhoyansk–Kolyma Mesozoides (belt folded during the Mesozoic) [24]. The background seismicity in the Omulevsky block suggests that this rootless terrane was detached from the neighbouring rocks as a result of horizontal displacements. was replaced by The Omulevsky block is viewed as a terrane that formed in the Mesozoic structural frame during collisional and post-collisional transformations of the Verkhoyansk–Kolyma belt . The background seismicity in the Omulevsky block suggests that this rootless terrane [24] was detached from the neighbouring rocks as a result of horizontal displacements.

Lines 427 and 429. Yes, there are right-lateral strike-slip faults.

Page 15

Line 439. Мs 6.6–6.8 7.1) was replaced by Мs 6.6)

Line 439. of dynamic influence  was removed

Line 444. reference [2] was added.

Line 451. parallel echelon was replaced by ‘en echelon’

Page 16

Figure 10 was changed. Insets A and B were enlarged.

Line 480. this fault we prefer use our variant

Line 480. seismogravitational data was replaced by effects

Page 17

Lines 520–521. The spatial orientations of the transitional stress axes are chaotic, and the dip angles vary in a wide range (from 0° to 82°). was replaced by The spatial orientation of the intermediate stress axis are chaotic, and the dip angles vary in a wide range (from 0° to 82°).     ????????

Page 18

Line 534. We understand reverse faults as planes with more steep dip, whereas thrusts are more gentle planes.   

Page 19

Line 568. ridge was replaced by Ridge

Line 575. southern flank was replaced by The Gakkel Ridge

Line 575. of the Eurasian basin was removed

Page 20

Lines 606–607. The models developed in our study can give a framework was replaced by Our results of the seismogeodinamyc analysis maybe used

Lines 613. Text was corrected.

Author Response File: Author Response.doc

Round 2

Reviewer 2 Report

Dear authors,

thank you for revising your manuscript and the explanations to questions I had.

There is still one sentence, I would not write as you did:

Lines 555,556: The Gakkel Ridge at the junction with the continental slope is represented by the Laptev Sea microplate.

I do not have further comments.

With best regards

Wolfram Geissler